GLIMMIX Procedure Research Articles

Effect of maternal heat stress at different stages of pregnancy on the reproductive performance and antral follicle count of the progeny of Holstein cows

The objective was to evaluate the effect of maternal exposure to heat stress conditions at different stages of pregnancy on the reproductive performance and antral follicle count of progeny. The study was conducted at five commercial dairy farms located in southeastern Brazil. Retrospective data (2002 and 2015) on reproductive indices of daughters of Holstein cows that were exposed to heat stress conditions in the first (n = 447), second (n = 729) or third (n = 746) trimester of pregnancy and daughters of cows not exposed to heat stress (n = 359) were analyzed. Antral follicle count (AFC) and ovarian size were determined in a subgroup of animals (n = 242) by transrectal ultrasound. Statistical analysis was performed using the SAS GLIMMIX procedure. The number of services after first calving was lower in daughters of cows not exposed to heat stress conditions than in those exposed during different trimesters of pregnancy (P = 0.03). The calving interval was longer for daughters of cows exposed to heat stress conditions in the second and third trimesters of pregnancy than for those not exposed to heat stress (P = 0.01). In addition, the probability of pregnancy at first AI, (P = 0.01) and the AFC (P = 0.001) were greater in daughters of cows not exposed to heat stress conditions than in those exposed during the different phases of the gestational period. These findings indicate that maternal heat stress in different stages of pregnancy negatively affect the future fertility and AFC of bovine offspring.

Grape pomace supplementation reduced methane emissions and improved milk quality in lactating dairy cows.

Grape pomace (GP) is a byproduct of the viticulture industry and shows promise for feeding dairy cattle as well as reducing enteric methane (CH4) emissions. This study investigates the potential of using fresh GP in dairy cow feeding and its effects on CH4 emissions. Multiparous Holstein dairy cows (n = 24, 205 ± 39 DIM) were housed in free stall barns and provided rations consisting of alfalfa hay, wheat hay, almond hulls, cottonseed, and grain mix. After a 2-wk adaptation period, cows were randomly assigned to one of the 3 treatments: a control diet (CON) a diet with 10% grape pomace (10% GP), and a diet with 15% GP (15% GP) on a DM basis. Treatments were arranged in a 3 × 3 Latin Square Design, where cows received 3 treatments over 3 periods, each period lasting for 4 wk. Rations were provided twice daily and gas emissions from cows were measured using an automated GreenFeed system. Milk production was recorded both in the morning and evening h and milk samples were collected weekly for fat, protein, lactose, SNF, MUN, and SCC analysis. For fatty acids analysis, milk samples were collected on the last 3 d of each 28-d period. Data were checked for normality and were analyzed using a mixed model ANOVA in proc GLIMMIX in SAS. Dry matter intake was reduced in GP-fed cow, where CON had the highest DMI followed by 10% and 15% GP. Methane and H2 emissions were reduced in GP-supplemented group compared with CON group. On the other hand, CO2 emissions was found higher in GP-supplemented group compared with the CON group. Milk yield was not different among different GP treatments. Although no differences were observed in fat, protein, lactose, SNF, and SCC, we did observe that MUN was lower in the 10% and 15% GP compared with CON group. The reduction in CH4 emissions in GP-supplemented group suggests that the chemical components of GP were effective in reducing CH4 emissions. On the other hand, lower DMI in GP supplemented groups indicates that DMI can act as an indicator of lower CH4 production. No effects on fat, protein percentage, and milk yield indicate that GP did not negatively affect milk production. Total PUFA and linoleic acid in milk fat, were greater in 10% and 15% GP groups compared with CON group. In conclusion, GP supplementation helped reduce enteric CH4 emissions from cows without impacting milk production.

Melatonin supplementation to sows in mid to late gestation affects offspring circadian, myogenic, and growth factors in pre and postnatal skeletal muscle.

The neuroendocrine hormone melatonin is associated with circadian rhythms and has antioxidant and vasodilative properties. In cattle, melatonin rescues fetal growth during maternal nutrient restriction in a seasonally dependent manner, but melatonin research in swine is limited. The objective of this study was to evaluate effects of dietary melatonin supplementation during mid to late gestation on circadian rhythm and muscle growth and development of the longissimus dorsi in utero and postnatally. Sows received 20mg dietary melatonin daily (MEL) or no melatonin supplement (CON). Experiment 1 supplemented sows from gestational age (dGA) 38 ± 1 to 99 ± 1, experiment 2 supplemented sows from 41 to 106 ± 1 dGA, and experiment 3 supplemented sows from 60 dGA to farrowing. At harvest, morphometric measurements of all fetuses were taken, while the small (SM), medium (MED), and large (LG) piglet from each litter were used for further analysis. Prenatal data were analyzed using the MIXED procedure of SAS, and postnatal data were analyzed using the GLIMMIX procedure. Fetal morphometrics were analyzed for fixed effect of treatment, and transcript abundance was analyzed for treatment, time, and size. Postnatal parameters were analyzed for fixed effects of treatment, size, and production stage. In Exp. 1, MEL increased (P = 0.016) Period 1 (PER1) transcript abundance in the evening (PM) compared to the morning (AM). In Exp. 1, myogenin (MYOG) transcript abundance was increased (P = 0.033) in MEL fetuses in the AM compared to MEL in the PM. Myogenic factor 5 (MYF5) and paired box 7 (PAX7) were increased (P = 0.016) in the PM. Fetuses from MEL treated sows had increased (P < 0.05) BW, curve crown rump length, and head circumference in Exp. 2. In Exp. 2, MEL increased (P = 0.012) PER1 and Period 2 (PER2) transcript abundance in the PM. In Exp. 2, myoblast differentiation 1 (MYOD) was increased (P = 0.016) in SM and MED fetuses, while MYF5 and PAX7 were increased (P = 0.019) in SM fetuses. Postnatal BW was increased (P = 0.025) in MED and LG MEL treated offspring compared to CON. Insulin-like growth factor 1 (IGF1) was downregulated (P = 0.050) in MEL treated offspring, while insulin-like growth factor 1 receptor (IGF1R) was upregulated (P = 0.009) in MEL offspring. These results indicate that maternal melatonin supplementation during gestation modulates fetal circadian regulatory genes and alters myogenic genes during growth.

Relative availability of five inorganic magnesium sources in non-pregnant non-lactating Holstein cows.

Inorganic sources of Mg are commonly used in dairy cow diets, but their availability varies significantly. This study assessed the relative availability of 4 commonly used inorganic Mg sources and a novel alkalinizing proprietary mineral blend [PMB; Multesium (GLC Minerals, LLC, Green Bay, WI, USA)]. The study was a duplicated 6 × 6 Latin square, with 12 nonlactating, non-pregnant Holstein dairy cows assigned to a square based on BW and parity. Cows were fed 90% of their voluntary DMI (diet contained 0.21% Mg). Each experimental period lasted 7 d. On d 2 of each period, urinary catheters were fitted. Total urine collection started on d 3 for 48 h with samples collected and measured every 12 h. On d 4, 30 g of Mg were administered as boluses with gelatin capsules: negative control (one empty capsule), magnesium oxide (MgO), magnesium sulfate (MgSO4), calcium magnesium hydroxide [CaMg(OH)4], calcium magnesium carbonate [CaMg(CO3)2], and PMB [a blend of Ca and Mg sources that includes CaMg(CO3)2, CaMg(OH)4, and MgO]. Blood samples were collected at 0, 1, 2, 3, 12, and 24 h after treatment administration on d 4 of each treatment period. Urine and blood samples were analyzed for Mg and Ca concentration. Statistical analyses were conducted with PROC GLIMMIX including treatment, time, period, square, treatment × time, treatment × period, and time × period as fixed effects, and cow nested within square as a random effect in the model. Urinary Mg excretion for 4 of the Mg sources studied [PMB, MgO, CaMg(OH)4, and MgSO4] increased significantly, representing an increase of at least 40.8% relative to control. The supplementation of CaMg(CO3)2 did not significantly increase relative to control. There were no significant changes in blood Mg concentration with treatment; but, a significant treatment × time effect was observed. Calcium-rich sources [PMB, CaMg(OH)4, CaMg(CO3)2] had lower blood Mg concentrations at 12 or 24 h after treatment than control and CaMg(CO3)2. Based on urinary Mg excretion 24 h after treatment, 4 of the Mg sources evaluated (including PMB) showed a similar availability, however, the availability of the commercial CaMg(CO3)2 source included in our study was similar to the negative control (no-supplemented cows).

Injectable progesterone in 13-month-old prepubertal Nellore heifers: effects on in vitro embryo production and pregnancy rate.

The aim of this study was to evaluate the effect of injectable progesterone administration before ovum pick-up (OPU) on in vitro embryo production (IVEP) and pregnancy rate in prepubertal Nellore heifers. Twenty-three Nellore females, 13.04 ± 0.8 months of age, were randomly assigned to two groups: control group (no progesterone application) and progesterone group (intramuscular administration of 1 mL [150mg/mL] progesterone 7 days before OPU). The second OPU was performed after 28 days (crossover between groups). After OPU, oocytes were selected for IVEP and a sample was fixed in 4% paraformaldehyde. Viable oocytes were subjected to immunofluorescence staining for IGFBP2 and caspase-3. For each oocyte, one image was generated per channel (A555 and A488 filters) and analyzed with the ImageJ program for the quantification of fluorescence intensity (in pixels). The produced embryos were transferred to multiparous Nellore cows and pregnancy was diagnosed by ultrasound 30 days after transfer. Data were analyzed using the MIXED and GLIMMIX procedure of SAS®. Treatment with injectable progesterone had no effect on the number or size of the antral follicles of heifers. No differences between the control and progesterone groups were observed for total number of aspirated oocytes (P = 0.78), viable oocytes (P = 0.80), cleavage rate (P = 0.60), or blastocyst rate (P = 0.56). There were no differences in pixel intensity between the two groups, nor in the levels of IGFBP2 or caspase-3. However, a difference was observed in the pregnancy rate of embryos produced from heifers of the progesterone group (42.1%; 32/76) when compared to the rate of embryos produced from control heifers (28.4%; 23/81) (P = 0.02). The use of injectable progesterone before OPU in prepubertal Nellore heifers does not improve IVEP but increases the pregnancy rate after transfer.

Seasonal environmental fluctuations alter the transcriptome dynamics of oocytes and granulosa cells in beef cows

BackgroundExamining the mechanistic cellular responses to heat stress could aid in addressing the increasing prevalence of decreased fertility due to elevated ambient temperatures. Here, we aimed to study the differential responses of oocytes and granulosa cells to thermal fluctuations due to seasonal differences. Dry beef cows (n = 10) were housed together, synchronized and subjected to a stimulation protocol to induce follicular growth before ovum pick-up (OPU). Two OPU’s were conducted (summer and winter) to collect cumulus-oocyte-complexes (COCs) and granulosa cells. In addition, rectal temperatures and circulating blood samples were collected during OPU. Oocytes were separated from the adherent cumulus cells, and granulosa cells were isolated from the collected OPU fluid. RNA was extracted from pools of oocytes and granulosa cells, followed by library preparation and RNA-sequencing. Blood samples were further processed for the isolation of plasma and leukocytes. The transcript abundance of HSP70 and HSP90 in leukocytes was evaluated using RT-qPCR, and plasma cortisol levels were evaluated by immunoassay. Environmental data were collected daily for three weeks before each OPU session. Data were analyzed using MIXED, Glimmix or GENMOD procedures of SAS, according to each variable distribution.ResultsAir temperatures (27.5 °C vs. 11.5 °C), average max air temperatures (33.7 °C vs. 16.9 °C), and temperature-humidity indexes, THI (79.16 vs. 53.39) were shown to contrast significantly comparing both the summer and winter seasons, respectively. Rectal temperatures (Summer: 39.2 ± 0.2 °C; Winter: 38.8 ± 0.2 °C) and leukocyte HSP70 transcript abundance (Summer: 4.18 ± 0.47 arbitrary units; Winter: 2.69 ± 0.66 arbitrary units) were shown to increase in the summer compared to the winter. No visual differences persisted in HSP90 transcript abundance in leukocytes and plasma cortisol concentrations during seasonal changes. Additionally, during the summer, 446 and 940 transcripts were up and downregulated in oocytes, while 1083 and 1126 transcripts were up and downregulated in the corresponding granulosa cells, respectively (Fold Change ≤ -2 or ≥ 2 and FDR ≤ 0.05). Downregulated transcripts in the oocytes were found to be involved in ECM-receptor interaction and focal adhesion pathways, while the upregulated transcripts were involved in protein digestion and absorption, ABC transporters, and oocyte meiosis pathways. Downregulated transcripts in the granulosa cells were shown to be involved in cell adhesion molecules, chemokine signaling, and cytokine-cytokine receptor interaction pathways, while those upregulated transcripts were involved in protein processing and metabolic pathways.ConclusionIn conclusion, seasonal changes dramatically alter the gene expression profiles of oocytes and granulosa cells in beef cows, which may in part explain the seasonal discrepancies in pregnancy success rates during diverging climatic weather conditions.

Risk factors underlining reproductive performance in smallholder beef cattle herds of South Africa

Improving the historically low reproductive performance of beef cattle in smallholder systems is essential for its productivity and profitability. Therefore, identifying and addressing risk factors associated with low performance in this system present an opportunity for improvement. The study aimed to evaluate the effect of animal and management risk factors on pregnancy rate (PR), fetal and calf loss (FC), calving interval (CI) and days open (DO) in smallholder beef cattle farms. A multi-stage selection approach was conducted in five provinces of South Africa. Cow records (3694) collected from 40 smallholder herds over two years (2018–2019) were analysed. Data on animal and herd management factors including body condition score (BCS), cow age class, breed type, lactation status, culling old/non-productive cows, record-keeping, and breeding and calving seasons were recorded. The GLIMMIX procedure was computed to determine risk factors associated with performance indicators (PR, FC, CI and DO). Risk factors highly associated with performance were breed type, BCS, cow-age class and breeding/calving season (P ≤ 0.05). Indicators FC, DO and CI increased with decreased BCS, autumn calving seasons, and in first calvers and aged cows. Whereas, PR increased with increasing odds of BCS and breeding seasons between December-March, November-February and January-March. Optimizing reproductive performance in smallholder beef cattle herds may involve managing cow body condition, breeding with adapted genotypes and synchronizing breeding with favourable seasons. Therefore, record keeping and regular monitoring of herd nutrition, climate and breed performance may be significant in improving reproductive performance in smallholder herds.

PSXII-24 Use of a commercial blend of tannins as feed additive for feed lot cattle on large pen trial improves carcass weight and carcass feed conversion

Abstract The utilization of commercial tannin extracts as feed additives holds promise for enhancing animal performance and health within commercial feedlot settings. This study aimed to assess the impact of a commercial tannin blend, SilvaFeed BX (Indunor, Buenos Aires, Argentina), sourced from quebracho and chestnut extracts along with saponins, on the performance of beef cattle. Nelore bullocks (n = 1,198) were allocated to 12 pens in a completely randomized block design, stratified by initial date, at a commercial feedlot facility in Goias State, Brazil. Each pen served as an experimental unit, with 10 pens housing 100 animals each and 2 pens containing 99 animals each. The experimental treatments included a Control diet with monensin alone [25 ppm/kg dry matter (DM)] or treated with BX (0.7 g/kg DM) on top of the control diet. Individual body weights (BW) were recorded at processing (initial BW; IBW) and shipment (final BW; FBW), while DM intake (DMI) was averaged per pen throughout the study duration. Carcass weight (CW) was individually measured at the packing plant, and carcass gain was calculated as the discrepancy between carcass weight and the estimated initial carcass weight, set at 50% of the IBW, aligning with customary practices for negotiating feeder cattle in Brazil. Statistical analyses were conducted using Proc Glimmix in SAS, treating pens and treatments as fixed effects and blocks as random effects, with IBW considered as a covariate. Residuals were assessed for normality, identifying three outliers. Mean comparisons were facilitated using LSMEANS. The results indicated that BX-treated cattle exhibited increased FBW (502.17 vs. 493.64 kg, P = 0.0992), carcass weight (275.76 vs. 268.78 kg, P = 0.0343), total carcass gain (107.52 vs. 100.54 kg, P = 0.0343), and improved carcass feed conversion (10.46 vs. 11.45 kg DM/kg; Table). Despite numerical differences, the limited number of replications were not enough to detect significant differences between treatments in average daily gain (P = 0.2419), DMI (P = 0.5508), feed conversion (P = 0.2641), or dressing (P = 0.3757). In conclusion, BX, a blend of tannins, exhibits potential for enhancing carcass weight and feed conversion efficiency in Nelore bullocks. Further investigations employing larger sample sizes are warranted to comprehensively elucidate its effects on other performance parameters.

PSXI-18 Effects of different fiber levels on rumination and inflammatory markers in feedlot cattle

Abstract Adding fiber to feedlot diets is essential to maximize performance, optimize feed conversion and maintain animal health. Monitoring blood inflammatory markers and rumination behavior can help to identify fiber levels that maximize performance and animal well-being. We aimed to evaluate the effect of fiber levels on inflammatory markers, lactate dehydrogenase and haptoglobin and rumination of Nellore cattle in confinement fed with diets containing 12% and 7% forage NDF, over a period of 50 d. Diets included corn silage as the source of forage fiber with 23.3% and 13.6% corn silage in the dry matter 64% and 73.5% ground corn, and 0.2 and 0.5% potassium chloride, respectively for the 12% and 7% fNDF. Soybean meal (1.5%); cottonseed (7%), urea (1.2%), and mineral mixture (2.7%) containing 25 ppm of monensin were present in both treatments. Average initial body weight (BW) was 460 ± 38 kg and average age was 20 mo. Bulls (n = 20) were randomly distributed for each treatment with animal being the experimental unit. The feeding behavior was monitored on d 21 and 42, with observations at each 10-min interval, over 24 h and data obtained were averaged for analysis and blood samples were collected immediately after behavior analysis. Blood samples were obtained by puncturing the jugular vein, centrifuged to separate the serum, stored at -20°C and subsequently analyzed. Lactate dehydrogenase was analyzed in an automatic biochemistry system using cattle specific cattle kits (LABTEST Diagnóstica SA). Haptoglobin analyses were carried out by ELISA (Vidavet-Veterinary Lab). Data were evaluated by PROC GLIMMIX from SAS. A significant interaction was observed between minutes of rumination and fNDF levels in relation to the concentration of lactate dehydrogenase (P &amp;lt; 0.0001), expressed by the solution: Lactate = 1,272.12 + 908.86 * (tract = 7) + 1,1427 -3.3170 * (treat = 7) * rumination. For animals receiving the 7% fNDF diet, the concentration of lactate dehydrogenase decreased as the minutes of rumination increased, with a significant linear effect (P &amp;lt; 0.001). On the other hand, for animals treated with 12% fNDF, no significant correlation was observed (P = 0.34) with increasing rumination time. There was also an interaction between minutes of rumination and fNDF levels for haptoglobin concentration (P &amp;lt; 0.01), expressed by the solution: Haptoglobin = 0.1901 + 0.4865 * (treat = 7) + 0.000828 - 0.00163 * (treat = 7) * rumination. In animals treated with 7% fNDF, haptoglobin concentration decreased with increasing minutes of rumination, with a significant linear effect (P = 0.02). Our data demonstrates that, for the low forage diet, as bulls increased rumination time there was an improvement (a decrease) in inflammatory markers concentrations.

PSII-14 Climate and conception: Investigating the resilience of equine embryo survival to ambient temperatures in southeast Texas

Abstract Amidst the unique challenges posed by the humid and hot climate of southeast Texas, this study aimed to assess the establishment of pregnancy from transferred equine embryos, hypothesizing that an increase in ambient temperature would lead to a decrease in pregnancy establishment. To achieve this, we utilized 17 embryo donors and 46 recipient mares (3 to 9 yr of age), all anatomically and clinically normal with no history of reproductive problems. Breeding records for 49 transferred d 8, grade-1 embryos from a single private horse farm in southeast Texas, along with the reported high and low ambient temperatures on the day of transfer, were analyzed using logistic regression via PROC GLIMMIX in SAS v9.4 with fixed effects for the reported high and low ambient temperatures on the day of transfer, with a random statement for donor and sire. The pregnancy rate for all embryo transfers was 79%. Surprisingly, our results revealed that neither the reported high ambient temperatures (P = 0.16) nor reported low ambient temperatures (P = 0.19) significantly influenced the likelihood of pregnancy establishment observed at d 14 post-ovulation of transferred equine embryos. Furthermore, no statistically significant influence (P &amp;gt; 0.05) on pregnancy establishment was observed when embryo transfers were conducted outside of the thermal neutral zone (5°C to 20°C). Within the context of our study, these results suggest that environmental temperatures in southeast Texas do not significantly impact equine pregnancy outcomes.

PSX-20 The inclusion of a tannin-based product evaluated in a typical feedlot diet under tropical conditions increases the molar proportion of propionate in a dual-flow continuous-culture system

Abstract The objective of the present study was to evaluate increasing levels of a tannin-based product and a monensin (positive control; unique dose) using a dual-flow continuous-culture system. Diets were randomly assigned to ten fermenters in a replicated 5 x 5 Latin square with three, 10-d experimental periods consisting of 7 d for adaptation and 3 d for sample collection. Four different levels were tested independently, resulting in 5 treatments: tannin at levels of 0 (negative control), 0.07, 0.14, and 0.21 (% of DM of the total diet) and monensin as positive control at 28 mg/kg DM. The tannin-based product was a specific blend of tannin and saponins, composed of quebracho and chestnut tannin extracts, SilvaFeed-BX). Diets were prepared as concentrate mixes that were combined with sugarcane bagasse, corn grain, dry distillers grain, citrus pulp, peanut meal, and urea. Liquid and solid flow rates were adjusted to 10 and 5.0%/h, respectively. Samples were collected for digestibility, ruminal fermentation, and microbial growth. The basal diet consisted of a typical finishing diet for beef cattle (16:84 roughage:concentrate ratio). All results were assessed for residual normality and variance homogeneity. All variables were fitted through generalized mixed models (GLIMMIX procedure) and compared by using Tukey test (multiple comparison) and polynomial regressions (tannin concentrations, which were analyzed for linear and quadratic responses. Partial data were presented in the table below. Total VFA concentration, molar proportion of butyrate, and total Branched-chain VFA were not affected by treatments (P &amp;gt; 0.05). Molar proportion of acetate of the tannin-based product at 0.07 % of DM tended to be decreased compared with all other treatments. Molar proportion of propionate increased quadratically (P = 0.05) reaching the peak at the level of 0.07 % of DM, which were greater than monensin treatment. In conclusion, our results indicate that a smaller dose of a tannin-based product (0.07 g/kg of DM) might manipulate ruminal fermentation by increasing molar proportion of propionate in typical feedlot diet fed under tropical conditions. This is important from an energetic standpoint for the animal host, since propionate is the precursor of glucose synthesis in ruminants.

PSIII-6 Multi-sire artificial insemination of beef heifers in the Nebraska Sandhills effect on pregnancy rate compared with single-sire insemination

Abstract The objective of this study was to compare pregnancy outcomes resulting from artificial insemination (AI) with multi-sire semen (MS) compared with single-sire semen (SS) in beef heifers. Another study observed pregnancy and paternity outcomes to sexed MS without a control treatment. In the first study, unrelated ABS Global Angus bulls (n = 3) were selected for AI to 441 (Yr 1) and 391 (Yr 2) Angus crossbred heifers. Heifers were synchronized with the melengestrol acetate – prostaglandin F2α timed-AI protocol. Conventional semen, from each bull, were labeled A, B, or C. Remaining semen was pooled in equal amounts to form conventional MS straws. Heifers were AI using alternating treatment of MS or SS: A, B, or C with one-half of inseminated heifers receiving either MS or SS. The GLIMMIX procedure in SAS 9.4 analyzed responses to treatments using the BIN distribution option and reported as LSMEANS. Contrasts and estimates analyzed responses between treatments. Ultrasound determined SS pregnancy rate averaged 60% (SS-A = 64%, SS-B = 58%, SS-C = 58%) and MS average 62% (P = 0.63). Paternity was determined in 57 MS calves and confirmed in 49 SS calves. In Yr 1, Bull A sired 7%, bull B sired 56%, and bull C sired 37%. Although bull A was much less successful than bull B or C, the values are not significantly different due to the small sample size (P = 0.11 and P = 0.24, respectively). Few conclusions can be made from the ongoing study, but it is hypothesized MS may improve consistency of pregnancy rate by equilibrating semen quality in herds subjected to timed AI. In the observational study, multiple 5-way cross bulls born from the ranch herd were selected for AI of 951 ± 41 heifers for 3 yr. Heifers were synchronized using the previously mentioned protocol with split-time AI. Unequal amounts of semen were collected, pooled, and sexed to favor heifer progeny at an expected ratio of 9:1. Semen from 2 to 4 random bulls were pooled making 3 to 4 MS groups each year. Heifers exhibiting estrus were administered sexed MS, but there was no control treatment. The observed ultrasound determined average pregnancy rate of heifers administered sexed MS was 65% (Yr 1), 75% (Yr 2), and 72% (Yr 3). Previous literature suggests average pregnancy rate to AI with sexed SS is 53%. Paternity testing in Yr 2 found semen contribution mirrored paternity ratios within some groups but the sire group with 2 bulls found one sired 15% and the other sired 85%. This study exemplified a viable method for AI that requires further research. Further research into semen quality of a single sire, and pooled semen could lead to optimization of fertilization among individuals within a herd.

PSV-25 Investigating the effects of Chromium Propionate supplementation on productive and reproductive performance of beef cows

Abstract We investigated the effects of Chromium Propionate supplementation on reproductive performance of beef cows from pre-partum to weaning. Suckled beef cows at nine locations were enrolled in the study. Within location, cows were stratified by parity, dam age, and day postpartum (DPP) and randomly assigned to one of two treatments: 1) Control, supplementation of a mineral product at 113 gּ animal-1ּ d-1 (n = 464 cows; 13 experimental units); or 2) CrP, supplementation of mineral product at 113 gּ animal-1ּ d-1 containing 1.4 g of Chromium Propionate (0.4%KemTRACE Chromium 0.4%, Kemin Industries, Inc., Des Moines, IA; n = 489 cows; 13 experimental units). Treatments were initiated at approximately 37 d pre-calving until weaning for a total of 250 ± 12 d. Cows were enrolled in the 7-d CO-Synch+CIDR fixed-time artificial insemination (TAI) protocol followed by natural service for a 70-d breeding season. Pregnancy diagnosis was performed by ultrasonography at 55 d after TAI protocol and 40 d after the end of the breeding season. Cow body weight (BW) and body condition score (BCS) were recorded at initiation of the TAI protocol (d -10), at pregnancy diagnosis (d 55 and 110), and at weaning (d 285). Within group, mineral disappearance was determined by the difference in weight between offered mineral and refusals. Data were analyzed using the GLIMMIX and MIXED procedures of SAS with pasture/group as the experimental unit with the effect of treatment and included group (treatment × location), cow (group), and location as random variables. Age, DPP, d -10 BCS, and BW were similar (P &amp;gt; 0.05) between treatments (5.4 and 5.3 ± 0.61 yr, 79.2 and 79.9 ± 4.61 d, 5.1 and 5.2 ± 0.05, 515.7 and 515.6 ± 15.11 kg for Control and CrP, respectively). Mineral disappearance was similar (P = 0.999) between treatments (165.5 and 152.9 gּ animal-1ּ d-1, for Control and CrP, respectively). Cow BW was similar (P &amp;gt; 0.05) between treatments on d 55, 110 and 285 (558.5 and 551.4 ± 14.50 kg, 580.8 and 594.6 ± 13.51 kg, and 574.2 and 570.9 ± 14.32 kg for Control and CrP, respectively). Similarly, cow BCS did not differ (P &amp;gt; 0.05) between treatments on d 55, 110 and 285 (5.4 and 5.4 ± 0.09, 5.3 and 5.3 ± 0.10, and 5.1 and 5.2 ± 0.10 for Control and CrP, respectively). Calf birth and weaning BW were similar (P &amp;gt; 0.05) between treatments. However, CrP-supplemented cows tended (P = 0.081) to have greater estrus expression (60.2 and 68.3 ± 3.1 %, for Control and CrP, respectively) and CrP-supplemented cows had greater (P = 0.045) TAI pregnancy rate when compared with Control cows (49.9 and 55.2 ± 2.1 %). Supplementation of Chromium Propionate to beef cows from pre-partum through weaning did not affect cow BW and BCS, tended to increase estrus expression and increased TAI pregnancy rate.

PSV-11 Significance of specialty protein ingredients in feeding programs for broiler chickens on nitrogen utilization and excretion- A meta-analysis

Abstract The utility of specialty protein ingredients (SPI) in feeding programs for broiler chickens is premised on poor utilization of conventional vegetable proteins (CVP). The SPI includes ingredients of animal origin such as processed animal proteins (PAP), insect proteins (IP) and further processed conventional vegetable proteins (PCVP) characterized with greater concentration of crude protein/amino acids, and low anti-nutritional factors. The objective of this study was to apply meta-analysis approach of published studies that incorporated SPI to provide insights into their effectiveness on nitrogen utilization and excretion in broiler chickens. The data were retrieved from Web of Science, PubMed, ScienceDirect, hand searching and cross-referencing, and resulted in 44 publications meeting inclusion criteria such as being a broiler study and treatments diets being isocaloric and isonitrogenous Model development was performed in PROC GLIMMIX of SAS and treated the study as a random effect. The SPI protein source (PAP, IP, and PCVP), bird age (starter 0 to 14 d, grower 14 to 24 d and finisher 25 to 42 d), nitrogen intake and level were the main X variables of interest, while outcome (Y) variables explored included nitrogen excretion, nitrogen retention, nitrogen efficiency, average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). To address heterogeneity in sample size and errors between treatment means from different studies, the WEIGHT statement in PROC GLIMIXX was employed to weight variables using the inverse of their squared variance. The inclusion or rejection of models developed was based on the evaluation of root mean square prediction error and concordance correlation coefficient. Comparatively, the slopes of PAP, IP and PCVP (soybean meal) linearly reduced and quadratically (P &amp;lt; 0.05) increased ADG during the starter phase against their respective controls. The extent ADG was greatest with intake of PCVP followed by PAP. During the grower phase, ADG was highest for PAP, followed by IP with PCVP being the least (P &amp;lt; 0.05). However, PCVP had the greatest ADG during the finisher phase (P &amp;lt; 0.05). On nitrogen excretion, provision of PAP during the stater phase increased the nitrogen excretion while it reduced the excretion during the grower and finisher phase (P &amp;lt; 0.05) relative to control. The intake of IP up to 10% inclusion reduced nitrogen excretion only during the starter and grower phase (P &amp;lt; 0.05) when compared with respective controls. The intake of PCVP reduced nitrogen excretion in all growth stages compared with respective controls (P &amp;lt; 0.05). In conclusion specialty proteins (PAP and PCVP) and insect protein at an inclusion level of &amp;lt; 10%, were effective ways of reducing nitrogen excretion while improving growth performance. Combining these strategies may have a synergistic effect.

PSVII-29 Integrating hybrid rye into organic pig production to reduce feed and bedding costs

Abstract An obstacle to profitable organic swine production is the high cost of feed and bedding. We evaluated whether growing hybrid rye for organic feed and bedding for pigs was economically viable by replacing corn with hybrid rye and evaluating pig growth performance and feed and bedding costs. Hybrid rye was grown on certified organic land at WCROC in 2022 and 2023. Rye grain and straw were used in a feeding trial with pigs raised according to the National Organic Standards. The animal trial consisted of three replicates. Each replicate included 100 pigs in two pens (Control vs. Rye, 50 pigs/pen) in a bedded hoop barn. Control pigs were fed corn soybean meal-based diets and Rye pigs were fed diets with 50% of corn in the control diets replaced by hybrid rye. Each replicate lasted for about 12 wk until pigs reached market weight (120 kg). Pigs were weighed individually at the beginning, every 4 wk thereafter, and at the conclusion of the study. Feed disappearance was recorded on a pen basis at the time of weighing pigs. Growth performance[average daily gain(ADG), average daily daily feed intake (ADFI), and Gain: Feed] was calculated for each weigh period. Carcass weight was recorded at harvest and dressing percent was calculated for each pig. Bedding usage was recorded for each pen (Control pen = wheat straw, Rye pen = rye straw) and average usage for each pig was calculated. Growth performance and bedding usage data were analyzed using the Proc Glimmix Procedures of SAS, with dietary treatment as the fixed effect, replicate as the random effect, and pen as the experimental unit. Production costs were set at $239/ha for organic rye grain and $20/ha for rye straw baling according to the FINBIN Database, and the unit costs ($/kg) were calculated based on yield for each year. Prices for organic corn, soybean meal, base mix, wheat straw, and market pigs were based on market prices (Table 1). Yield of organic hybrid rye grain at WCROC was 1,070 and 712 kg/ha in 2022 and 2023, respectively, with corresponding rye straw yield being 661 and 367 kg/ha. The reduction in rye yield in 2023 was considered due to drought. No difference was detected in growth performance, dressing percent, or bedding usage between Control and Rye pigs (all P &amp;gt; 0.19; Table 1). Replacing 50% of corn with hybrid rye saved $9.6/pig in 2022, but cost $7.20/pig more for feed in 2023, due to changes in hybrid rye grain yield. Savings on bedding were $15.40 and $13.20/pig for 2022 and 2023, respectively. Results indicate that replacing 50% of corn with hybrid rye in feed did not negatively affect growth performance of pigs raised organically, but the economic viability of integrating hybrid rye into organic pig production may depend on crop yield.

PSLBI-5 Ruminal papillae morphology of beef on dairy heifers with abscessed or non-abscessed livers

Abstract The ruminal papillae morphology characteristics of feedlot beef on dairy non-spayed heifers with liver abscess to those with non-abscessed liver were evaluated. Heifers were sourced from 27 lots which were harvested on six dates between November 2022 and February 2023. Upon harvest, a total of 94 rumen tissue samples from animals presenting liver abscesses and 110 rumen tissue samples from animals with non-abscessed livers were collected in pairs, as abscesses were identified within the harvesting facility viscera inspection line, following a randomized complete block design (block = lot within harvest date). Individual fragments (6 cm2) from the cranial sac epithelium of the rumen were collected, rinsed with deionized water, immersed in 70% alcohol, and preserved under refrigeration (4 oC) until analysis. Ruminal tissues were trimmed (1 cm2), in which the number of papillae was counted by three trained personnel, followed by the removal of 12 representative papillae specimens for further area electronic scanning (The University of Texas Health Science Center of San Antonio, Image Tool) to determine average papillae area, number per cm2 (AVP), average papillae area in cm2 (APA), absorptive surface area in cm2/fragment cm2 (ASA), and papillae absorptive surface area, % (ASA). Data were analyzed using the GLIMMIX procedures of SAS, with individual animal ruminal tissue used as the experimental unit, the fixed effect of ruminal condition, and the random effect of lot within the harvesting date. Average papillae number (P = 0.27), average papillae area (P = 0.74), absorptive surface area (P = 0.48), and papillae absorptive surface area (P = 0.43) were not affected by the presence of liver abscess. Severity of liver abscess distinguished as A -, A, or A+ scores compared with non-abscessed liver showed no difference on papillae number (P = 0.34), papillae area (P = 0.89), and absorptive area (P = 0.62). The presence of small or large liver abscesses did not affect the papillae area, size, or absorptive area (P ≥ 0.41). The liver lobe location of abscesses (cranial, caudal, both) did not affect (P ≥ 0.17) any of the ruminal morphological variables measured. The presence of liver abscesses, whether diffuse or localized, in beef on dairy heifers, did not affect (P ≥ 0.58) the development of ruminal papillae. The presence, severity, or location of liver abscess was not connected with ruminal papillae number, area, or absorptive surface area of beef on dairy heifers measured upon harvest time. The absence of ruminal papillae morphological changes in animals committed with liver abscesses may be further investigated with the characterization of potential cellular physical changes of the ruminal tissue and the integrity of the primary barrier in the digestive tract.

PSIX-26 Effectiveness of mineral supplementation during range grazing on mineral status in ewes

Abstract Mineral supplementation in the intermountain west region of the US may be necessary for maintenance of healthy flocks since important trace minerals are deficient in this region. However, rough terrain can make mineral supplementation challenging. The objective of this study was to evaluate the trace mineral status of ewes on range. We hypothesized that ewes with access to a mineral supplement would have decreased risk of mineral deficiency. In this study, ewes (n = 59) grazed four summer pastures on Cedar Mountain near Cedar City, Utah. Ewes between the ages of 1 and 6 yr of age were stratified by initial body weight (BW) = 87 kg ± 13 kg and breed [black face (BLF; Suffolk) and white face breeds (WF; Targhee, Rambouillet, and their crosses)] into two treatment groups 1) trace mineral supplement ad libitum (TRT; n = 7 BLF and 23 WF) or 2) no mineral supplement (CON; n = 15 BLF and 14 WF). All ewes received a diet of mixed alfalfa and triticale hay without mineral supplementation 30 d before the trial began. A SmartFeed (C-lock Inc.) was used to track individual animal mineral intake. Plasma samples were collected via jugular venipuncture at d 0, 34, 77, and 116. A clinical veterinarian from Utah State University performed liver biopsies at d 0 and 116 on a subset of ewes (n = 10). After the grazing season, plasma and liver samples were sent to the Iowa State University Veterinary Diagnostic Laboratory for analysis of Cu, Mn, Se, and Zn. The mixed procedure of SAS was used to analyze plasma mineral content with day as a repeated measure and individual ID as a random variable. The Glimmix procedure of SAS was used to analyze liver mineral content. Plasma Cu and Se increased (P ≤ 0.05) by day in all ewes throughout the grazing season. No differences related to treatment or breed (P &amp;gt; 0.10) were observed for plasma Cu or Se concentrations. Plasma Mn and Zn decreased (P &amp;lt; 0.0001) by 1.5 ppb and 0.4 ppm, respectively, between d 0 and 116 with no treatment effect (P &amp;gt; 0.10). BLF ewes had 0.3 ppm (P = 0.01) greater plasma Mn concentrations than WF ewes, with no difference (P = 0.6) observed due to treatment. Hepatic Cu and Se increased (P ≤ 0.05) by 114 ppm and 1 ppm, respectively, between d 0 and 116. Hepatic Mn concentrations did not differ (P &amp;gt; 0.10) by day or treatment. Hepatic Zn concentrations tended to increase by day (P = 0.07), 23 ppm between d 0 and 116. CON ewes had 28 ppm greater (P = 0.04) hepatic Zn concentrations than TRT ewes. Additional research is warranted to understand why CON had greater hepatic Zn concentrations than TRT, which may indicate that diverse rangeland forages may provide sufficient concentrations for sheep production in summer months.

PSX-14 Effect of starch supplementation on rumen bacterial abundance in Bos taurus taurus steers consuming low-quality forage

Abstract Low-quality forage provides a limited supply of ruminally available nitrogen and is generally resistant to digestion, inhibiting microbial growth in the rumen and ultimately decreasing forage utilization. Supplementation with protein is well documented to increase forage utilization by promoting microbial growth. Even when protein requirements are met, additional energy, often provided as starch, may be required to meet performance expectations. The objective of this study was to evaluate the effect of increasing starch supplementation on rumen bacterial populations in Bos taurus taurus steers supplemented protein and consuming low-quality forage. Ruminal samples were collected from ruminally-cannulated Angus steers [n = 5; body weight (BW) = 375 ± 45 kg] used in a 4 × 4 Latin square fed a basal diet of King Ranch Bluestem Hay (3.5% CP, 73% NDF) ad libitum, and supplemented with one of four isonitrogenous (130 mg N/kg BW) supplements with increasing starch (2% starch = 100% soybean meal; 20% starch = 73% soybean meal, 26.2% corn, 0.8% urea; 38% starch = 47% soybean meal, 51.6% corn, 1.4% urea; 56% starch = 19% soybean meal, 78.6% corn, 2.4% urea). Rumen content samples were collected via rumen cannula 4 h after supplementation and immediately frozen. Microbial DNA was extracted; full length 16S rRNA amplicon libraries were prepared using Kinnex kits and sequenced on the PacBio Revio platform. Reads were analyzed using DADA2 and QIIME2. Statistical analysis was performed with the GLIMMIX procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC). Firmicutes and Bacteriodata were the most abundant phyla in all treatments (82% and 11%, respectively), and were not affected by starch supplementation (P ≥ 0.45). Actinobacteriota and Euryarchaeota abundance responded quadratically (P &amp;lt; 0.01) to increasing starch provision. Christensenellaceae R-7 group, Rikenellaceae RC9 gut group, Lachnospiraceae XPB1014 group, Butyrvibrio, Lachnospiraceae NK3A20 group, and Prevotella represented the most abundant genera for all treatments. Increasing supplemental starch resulted in a quadratic response (P &amp;lt; 0.01) for abundance of Christensenellaceae R-7 and Lachnospiraceae XPB1014 groups. Relative abundance of Butyrvibrio was 4.05% for steers fed 2% starch supplement and increased to 18.24 and 11.85% for 20 and 38% starch, respectively and then decreased to 4.34% for steers fed 56% starch supplement (quadratic, P &amp;lt; 0.01) Abundance of Pseudobutyrvibrio followed a similar but less dramatic pattern (quadratic, P &amp;lt; 0.01). In contrast, abundance of Streptococcus and Methanobrevibacter decreased with the first two levels of starch and then increased with 56% (quadratic; P &amp;lt; 0.01). In conclusion, responses to the first two increments of starch supplementation suggest increased fibrolytic and decreased methanogenic activity. These results are supported by the previously reported increase in TDOMI for 20 and 38% starch 49.0 and 48.2 g/kg MBW, respectively versus 45.7 and 44.3 g/kg MBW for 2 and 56%, respectively.

PSX-15 Effect of starch supplementation on rumen bacterial abundance in Bos taurus indicus steers consuming low-quality forage

Abstract Deficient ruminally available nitrogen caused by a basal diet of low-quality forage can limit microbial growth in the rumen and decrease forage utilization. Protein supplementation is well-documented to improve forage digestibility and performance. Additionally, starch has been evaluated to increase energy supply to grazing cattle when the forage cannot support adequate levels of production. However, most research in this area has been conducted in Bos taurus taurus, especially the response of the rumen microbiome to supplementation. Accordingly, the objective of this study was to evaluate the effects of increasing starch supplementation on rumen bacterial populations in Bos taurus indicus steers supplemented protein and consuming low-quality forage. Ruminal samples were collected from five ruminally-cannulated Brahman steers (BW 420 ± 55 kg) used in a 4×4 Latin square fed a basal diet of King Ranch Bluestem Hay (3.5% CP and 73% NDF) provided ad libitum, and one of four isonitrogenous (130 mg N/kg BW) supplements with increasing levels of starch (2% starch= 100% soybean meal; 20% starch= 73% soybean meal, 26.2% corn, 0.8% urea; 38% starch = 47% soybean meal, 51.6% corn, 1.4% urea; 56% starch= 19% soybean meal, 78.6% corn, 2.4% urea). Rumen content samples were collected via rumen cannula at 4h post-feeding. Microbial DNA was extracted; full length 16S rRNA amplicon libraries were prepared using Kinnex kits and then sequenced on the PacBio Revio platform. Reads were analyzed using DADA2 and QIIME2. Statistical analysis was performed with the GLIMMIX procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC). Firmicutes, Bacteroidata, Actinobacteriota, Verrucomicrobiota, and Euryarchaeota were the most abundant phyla in all treatments (83, 10, 3, 0.4, and 1%, respectively), and were not affected by treatment (P ≥ 0.10). Christensenellaceae R-7 group, Rikenellaceae RC9 gut group, Lachnospiraceae-XPB1014-group, Butyrvibrio, Lachnospiraceae-NK3A20-group, and Prevotella represented the most abundant genera for all treatments (7, 5, 11, 9, 7, and 3%, respectively). Lachnospiraceae-XPB1014-group and Lachnospiraceae-NK3A20-group responded quadratically (P ≤ 0.02) to increasing starch with decreased abundance for the 20% and 38% starch supplement. Comparatively, relative abundance of Butyrvibrio responded quadratically (P &amp;lt; 0.01) with increased abundance in the 20% and 38% starch supplement. Pseudobutyrvibrio increased with supplementation of 20% starch and then decreased as starch supplementation increased (quadratic, P = 0.04). In conclusion, supplementation of starch elicited changes in microbial relative abundance at the genus level with the response in Butyrivibrio suggesting greater fibrolytic activity. Forage and total digestible NDF intake in these steers decreased with increased starch supplementation; however, TDOMI was not affected by starch provision.

PSIII-7 Effects of Saccharomyces cerevisiae fermentation product on total tract digestibility, ruminal fermentation, and plasma metabolome of beef steers fed a finishing diet

Abstract Saccharomyces cerevisiae fermentation product (SCFP) has been widely studied; however, its mode of action on high-concentrate diets has not been fully elucidated. This study evaluated the impact of SCFP on total tract digestibility, fecal excretions of N, P, Zn, and Cu, rumen fermentation, and plasma metabolome of finishing beef steers. Ruminally cannulated Holstein steers [n = 8; body weight (BW) = 580 ± 29.2 kg] were enrolled in a crossover design study with 25-d treatment periods and a 24-d washout period. Steers were fed ad libitum a finishing diet consisting of 20% corn silage and 80% concentrate (on DM basis). Steers were blocked based on initial BW and randomly assigned to two treatments in period 1 and switched to the other treatment in period 2. The treatments were CON (Control, basal diet only) and SCFP (basal diet top-dressed with 12 gּ steer-1ּ ּ d-1 SCFP, NaturSafe, Diamond V, Cedar Rapids, IA). Feed and fecal samples were collected during d 22 to 24 for determination of digestibility. Blood was collected before morning feeding on d 25. Plasma samples were analyzed for metabolome with liquid chromatography-mass spectrometry (LC-MS). Rumen fluid was collected via the rumen cannula at 0, 4, 8, and 12 h post-morning feeding on d 25 and analyzed for pH, volatile fatty acids (VFA), and NH3-N. Performance and ruminal fermentation characteristics data were analyzed using the GLIMMIX procedure of SAS 9.4. Metabolomic data analysis was conducted with Metaboanalyst 6.0. Supplementing steers with SCFP reduced DMI (10.6 vs. 11.4 kg/d, P = 0.05) without affecting (P &amp;gt; 0.05) average daily gain, feed efficiency, and digestibility of organic matter, crude protein, and neutral detergent fiber. Treatment did not affect (P &amp;gt; 0.10) fecal excretions of N, P, Cu, and Zn. Feeding SCFP increased ruminal pH (6.29 vs. 6.01, P = 0.01), numerically reduced concentrations of NH3-N (5.01 vs 6.25 mM, P = 0.16), and total VFA (96.8 vs. 102.5 mM, P = 0.15). SCFP also reduced the ruminal molar proportion of butyrate (11.2 vs. 12.8 molar %, P = 0.01) and tended to increase those of isobutyrate (1.03 vs. 0.90, molar %, P = 0.06) and isovalerate (2.62 vs. 2.29, molar %, P = 0.10). Supplementation of SCFP enriched (P ≤ 0.05) purine metabolism, amino sugar and nucleotide sugar metabolism, and lysine degradation pathways in the plasma. Additionally, tryptophan metabolism and pyrimidine metabolism pathways tended to be enriched (0.05 &amp;lt; P ≤ 0.10) by SCFP. Our findings indicate that feeding SCFP improved the ruminal pH of finishing cattle, which may be beneficial for preventing subacute ruminal acidosis in feedlot cattle. Additionally, SCFP enriched several important plasma nitrogen metabolism pathways, potentially associated with microbial nitrogen metabolism in the rumen, warranting further research.