Performance Of Beef Cows Research Articles

PSVII-30 Winter-feeding high concentrate diets reduces enteric methane emissions pre-calving in beef cows

Abstract Objectives were to evaluate the effects of winter-feeding forage (2.02 Mcal/kg dietary ME) vs. concentrate (2.84 Mcal/kg of dietary ME) diets pre- and post- calving on enteric methane emissions, dry matter intake (DMI), and performance of beef cows. Forty-six pregnant (210 ± 10 d of gestation) Angus and Simmental-Angus cows [n = 46; body weight (BW) = 630 ± 12.0 kg) were blocked by breed, age, and BW and assigned to one of two treatments: 1) Ad-libitum feeding of forage-based diet (HFOR; n = 23); or 2) a concentrate corn-based diet with a restricted intake of 1.2% BW (HCON; n = 23). Cows were housed in a group-pen at the South Dakota State University Cow-Calf Education and Research Facility (Brookings, SD). Feed consumption was tracked using an electronic feeder (Insentec, The Hague, Netherlands) and enteric methane emissions were monitored using the GreenFeed trailer system (C-Lock Inc., Rapid City, SD). Body weight measurements were taken bi-weekly. Treatments started being applied on d 50 (± 10) pre-calving and will continue to be applied up to d 84 post-calving. Preliminary data reported herein was collected from d 42 pre-calving up to d 42 post-calving. Performance and dry matter intake data were analyzed as repeated measures using the MIXED procedure of SAS with treatment, period, and their interaction as fixed effects and animal as a random effect. Enteric emissions were analyzed using a linear mixed effects model with animal as a random effect in R, with a post-hoc contrast among treatments. Pre-calving, HFOR had greater (P < 0.01) CH4 emissions than HCON (264 ± 9.19 g/d and 246 ± 9 g/d for HFOR and HCON, respectively). Both groups presented dynamic changes in CH4 emissions over time (P < 0.01). Post-calving, no differences were observed between treatments (P = 0.55); however, temporal changes (P < 0.01) and treatment × d interaction (P < 0.01) persisted, indicating ongoing diet-temporal interplay. No treatment × period interactions (P ≥ 0.16) were observed for DMI and performance. As designed, dry matter intake was less (P < 0.01) for HCON (8.66 ± 0.45 kg) than HFOR (17.3 ± 0.45 kg) cows. Further, dry matter intake was less (P < 0.01) pre-calving (11.11 ± 0.28 kg) than post-calving (14.85 ± 0.48 kg). Cows in the HFOR group were heavier (P = 0.01) than HCON (646.22 ± 14 kg vs. 593.43 ± 14 kg, respectively) likely due to ruminal fill; and as expected cows were heavier (P < 0.01) pre- than post-calving, with the greatest BW observed on d 14 pre-calving (639.52 ± 9.92 kg). These data indicate that high concentrate corn-based diets may be used in dry-lot settings to optimize nutritional management and reduce methane emissions when compared with conventional high forage winter-feeding strategies.

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 > 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 > 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 > 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 > 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.

507 Effects of simple and complex polycrop mixtures on forage yield and quality, beef cow performance, and methane emissions

Abstract Polycrop mixtures are of increasing interest to western Canadian beef producers as alternative forages for grazing as they may promote plant biodiversity and nutritive value. This 2-yr study evaluated the effects of swath grazing either simple or complex polycrop mixtures on forage yield and quality, beef cow performance, and methane emissions. Forage treatments included 1) CDC Haymaker oat (Avena sativa; Control); 2) CDC Haymaker oat, Goliath brassica (Brassica napus), hairy vetch (Vicia villosa), CDC Jasper pea (Pisum sativum; Simple); and 3) CDC Haymaker oat, Goliath brassica, hairy vetch, CDC Jasper pea, CDC Maverick barley (Hordeum vulgare), Red proso millet (Panicum miliaceum), Teff grass (Eragrostis tef) and Choice chicory (Cichorium intybus; Complex). Dry pregnant beef cows [n = 90; body weight (BW) = 607.2 ± 32.3 kg; body condition score (BCS) = 2.9 ± 0.06] blocked by BW were randomly allocated to 1 of 9 paddocks (10 cows/paddock). Paddocks were randomly assigned 1 of 3 replicated (n = 3) systems. Cow BCS was measured at start (SOT) and end (EOT) of trial. Cow BW was recorded on 2 consecutive days at the SOT and EOT, and every 21 d during trial. Cows grazed for an average of 52 d from October to December (Control 51 ± 9.07 d; Simple 54 ± 9.20 d; Complex 53 ± 12.41 d). Data were analyzed as a completely randomized block design using the mixed model of SAS (9.4). Year and paddock were included as a random effect. Forage dry matter yield (DMY) was similar (P = 0.44) among Control (4,369 kg/ha), Simple (4,053 kg/ha), and Complex (4,245 kg/ha) treatments. Start of trial forage crude protein (CP) and total digestible nutrients (TDN) did not differ (P = 0.18 and P = 0.14) among treatments (Control 13.3% CP and 74.4% TDN; Simple 14.76% CP and 71.51% TDN; Complex 14.95% CP and 74.46% TDN). End of trial forage CP and TDN did not differ (P = 0.57 and P = 0.20) among treatments (Control 13.9% CP and 69.5% TDN; Simple 13.9% CP and 69.9% TDN; Complex 13.2% CP and 72.4% TDN). Cow BCS and average daily gain did not differ among forage treatments (P = 0.60 and P = 0.45, respectively). Cow dry matter intake (DMI) was similar (P = 0.19) among treatments (Control 11.13 kg/d; Simple 9.74 kg/d; Complex 9.96 kg/d). Methane emissions were greatest (P = 0.04) for cows grazing Simple (28.7 CH4 g/kg DMI) and Complex treatments (28.2 CH4 g/kg DMI) compared with monoculture oat treatment (22.6 CH4 g/kg DMI). Study results suggest that simple or complex polycrop mixtures may be used as forage alternatives to a monoculture oat grazing system as they produce adequate biomass and had nutritive value suitable for gestating beef cows.

Performance and metabolic evaluation in primiparous beef cows under grazing at different breeding ages.

We aimed to evaluate the metabolic and performance differences in primiparous Nellore cows, which became pregnant at 14 or 24-mo old. Thirty-eight cows with 202 ± 5 days of gestation were divided into two treatments according to breeding age: 14 or 24-mo. Cows were evaluated for body weight (BW), body condition score (BCS), carcass characteristics, milk yield, calves's performance, and blood characteristics. The animals were managed in eight paddocks under continuous grazing and evaluated from 90 d before parturition until 240 d after calving. We observed an interaction between breeding age and time (P < 0.01) for cow BW. Both breeding age categories experienced BW loss during parturition, with a concurrent decrease in BCS. However, following their first calving, the BW of 24-mo cows remained stable (P > 0.05), whereas 14-mo cows exhibited a gradual recovery in BW after parturition (P < 0.05). Milk yield was greater in 24-mo animals (P < 0.01), but decreased with increasing milking days (p < 0.05) for both groups. The weight gain calves from the heifers bred at 24-mo was greater (P < 0.01), which reflected in greater BW at weaning. The beta-hydroxybutyrate (β-OHB) concentration was greater before calving and a marked decrease after parturition (P < 0.05). The 24-mo cows had greater blood β-OHB (P < 0.01) at prepartum and 30 days after calving. Blood progesterone was greater in 24-mo cows (P > 0.05). Primiparous beef cows that conceive at either 14 or 24-months of age exhibit distinct nutritional requirements and metabolic profiles. Notably, cows that conceive at 24-months of age have the advantage of weaning heavier calves and displaying a more consistent reproductive cycle following their first calving than cows that conceive at 14-months.

Dietary guanidinoacetic acid as arginine spare molecule for beef cows at late gestation: Effects on cow’s performance and metabolism, and offspring growth and development

We aimed to assess whether guanidinoacetic acid (GAA) affects the performance, metabolism, and placental vascularization of pregnant beef cows during late gestation as well as its impact on the offspring’s performance. Twenty-eight pregnant Brahman cows, averaging 532±15.1 kg and carrying male (n=15) and female (n=13) fetuses, were used. The basal diet consisted of 688 g/kg corn silage, 147 g/kg sugarcane bagasse, 47.7 g/kg corn, 89.6 g/kg soybean meal, 6.86 g/kg urea, and 21.2 g/kg mineral mixture (DM basis). Cows were fed the experimental diets from 180 to 270 days of gestation. The following treatments were evaluated: control (no addition of GAA) or addition of 0.2 % GAA to the total diet (DM basis). There was no effect (P≥0.37) of GAA on voluntary intake. Similarly, GAA addition did not affect (P≥0.54) cows performance variables, except for ribeye area (REA), which had a lower (P<0.01) variation compared to the initial REA in cows fed dietary GAA compared to the control group. Dietary GAA increased (P≤0.02) both serum nitric oxide and placental vascularization compared to cows fed the control diet. There was no effect (P≥0.43) of GAA on urine and serum creatine concentrations. In contrast, dietary GAA increased (P≤0.03) plasma concentration of arginine, ornithine, citrulline, and tyrosine compared to the control. Conversely, dietary GAA decreased (P<0.02) plasma methionine concentration. Dietary GAA increased AGAT activity (P<0.03) in the liver, with no differences observed (P>0.68) on GAMT activity. There was no effect (P≥0.15) of GAA on performance of the offspring. Addition of GAA in maternal diet did not affect skeletal muscle fiber number (P>0.09) and diameter (P>0.23) of the offspring. Guanidinoacetic acid decreases skeletal muscle mobilization and enhances placental vascularization of beef cows during late gestation. However, providing GAA seems to not affect the performance of the offspring.

Protein supplementation during mid-gestation affects maternal voluntary feed intake, performance, digestibility,and uterine blood flow of beef cows.

This study aimed to assess the impact of protein supplementation and its interaction with calf sex (CS) on the performance, metabolismand physiology of pregnant beef cows. Fifty-two multiparous Zebu beef cows carrying female (n = 22) and male (n = 30) fetuses were used. Cows were individually housed from day 100 to 200 of gestation and randomly assigned to restricted (RES, n = 26) or supplemented (SUP, n = 26) groups. The RES cows were ad libitum fed a basal diet (corn silage + sugarcane bagasse + mineral mixture), achieving 5.5% crude protein (CP), while SUP cows received the same basal diet plus a protein supplement (40% CP, at 3.5 g/kg of body weight). All cows were fed the same diet during late gestation. Differences were declared at p < 0.05. No significant interaction between maternal nutrition and calf sex was found for maternal outcomes (p ≥ 0.34). The SUP treatment increased the total dry matter (DM) intake (p ≤ 0.01) by 32% and 19% at mid- and late-gestationrespectively. The total tract digestibility of all diet components was improved by SUP treatment at day 200 of gestation (p ≤ 0.02), as well as the ruminal microbial CP production (p ≤ 0.01). The SUP treatment increased (p ≤ 0.03) the cows'body score condition, ribeye area, the average daily gain (ADG) of pregnant components (PREG; i.e., weight accretion of cows caused by pregnancy)and the ADG of maternal tissues (i.e., weight accretion discounting the gain related to gestation) in the mid-gestation. The SUP cows exhibited a lower maternal ADG (p < 0.01) compared to RES cows in late pregnancy. There was a 24% additional gain (p < 0.01) in the PREG components for SUP cows during late gestation, which in turn improved the calf birthweight (p = 0.05). The uterine arterial resistance and pulsatility indexes (p ≤ 0.01) at mid-gestation were greater for RES cows. In conclusion, protein supplementation during mid-gestation is an effective practice for improving maternal performance, growth of the gravid uterusand the offspring's birth weight.

Periparturient Changes in Voluntary Intake, Digestibility, and Performance of Grazing Zebu Beef Cows with or without Protein Supplementation.

We aimed to understand the changes in nutritional parameters and performance of beef cows during the peripartum, whether receiving or not receiving protein supplements. Forty cows were used, divided into two treatments: CON-mineral mix and SUP-protein supplementation. Digestibility trial was performed at 45, 30, and 15 days (d) before the parturition and at 20 and 40 d of lactation. The ADG of cows pre- and postpartum was recorded along with the BCS in gestational (GT) and maternal (MT) tissues in the prepartum. There was an effect of treatment and period (p ≤ 0.044) for intakes of DM and CP. The forage intake was similar (p > 0.90) but varied with the effect of days related to parturition (p < 0.001). There was a 14.37% decrease in DM intake from d -30 to d -15 of prepartum. In the postpartum, at 20 d of lactation, there was an increase of 72.7% in relation to d -15 of prepartum. No differences were observed in postpartum ADG or BCS at parturition and postpartum (p ≥ 0.12). However, higher total and MT ADG (p ≤ 0.02) were observed in animals receiving supplementation, while ADG in GT remained similar (p > 0.14). In conclusion, there is a decrease in intake for pregnant cows close to parturition and greater performance of animals supplemented in prepartum.

Early induction of luteolysis in a timed AI protocol increases reproductive performance in beef cows

The aim of this study was to produce a longer proestrus by early administration of prostaglandin F2α (PGF) in a timed artificial insemination (TAI) protocol in non-suckling Bos taurus (Angus crossbreed) beef cows. On day 0, cows (n = 489) were treated with an intravaginal 1 g progesterone (P4) device and 2 mg of estradiol benzoate. On day 7, cows were randomized into two groups: PGF7(n = 244; 500 µg of sodium cloprostenol 24 h before P4 device removal) or PFG8 (n = 245; 500 µg of sodium cloprostenol at P4 device removal). On day 8, P4 device was removed and cows received 0.5 mg of estradiol cypionate. All cows were submitted to TAI on day 10 (48–50 hours after P4 device removal). Cows treated with PGF on day 7 had greater expression of estrus (91.3 vs 79.1 %; P = 0.0011), regardless of CL presence at beginning of the protocol. Cows from PGF7 group had lower circulating P4 concentrations on day 8 in comparison with PGF8 treated cows (1.86 vs 2.99 ng/mL; P < 0.001). However, preovulatory follicle diameter did not differ among treatments at TAI (11.9 vs 11.8 mm; P = 0.7881). Pregnancy per TAI (P/TAI) was greater for PGF7 (63.9 vs 50.6 %; P = 0.0114) than PGF8 treated cows. In cows with follicles <8.5 mm at TAI, expression of estrus (33.3 vs 26.6 %; P = 0.6427) and P/TAI (40 vs 26.6 %; P = 0.3657) were low in both PGF7 and PGF8 treated cows, respectively. In cows with medium follicle size (8.5 to 11.9 mm) PGF7 treated cows had greater expression of estrus (90.5 vs 80 %; P = 0.033) and P/TAI (62.2 vs 49 %; P = 0.053). In cows with follicles >12 mm, expression of estrus was greater for PGF7 than PGF8 treated cows (99.1 vs 93.3 %; P = 0.045), however P/TAI did not differ (68.2 vs 59 %; P = 0.149). In cows with P4 < 1.99 ng/mL on day 8, expression of estrus was similar between PGF7 and PGF8 treated cows (92.6 vs 90.4 %; P = 0.53), and P/TAI tended to be greater for PGF7 than PGF8 treated cows (63 vs 52.1 % P = 0.076). However, in cows with P4 > 2 ng/mL PGF7 cows had higher expression of estrus (89 vs 67.5 %; P = 0.0005) and P/TAI (64.8 vs 48.7 %; P = 0.021) than PGF8. Thus, increasing the proestrous period by inducing luteolysis 24 hours earlier than removing the P4 intravaginal device enhanced fertility in non-suckling cyclic beef cows by increasing expression of estrus and P/TAI.

28 Investigating the effects of Chromium Propionate supplementation on reproductive performance of beef cows

Abstract The objective of this study was to explore the effects on reproductive performance of beef cows supplemented with Chromium Propionate during the post-partum and breeding periods. A total of 955 multiparous suckled beef cows located at eight locations were enrolled in the study. Within location cows were stratified based on parity, body condition score (BCS), and days postpartum (DPP) and randomly assigned to one of two treatments: 1) Control- supplementation of a mineral product at 113 g animal/d (n = 484 cows; 16 experimental units); or 2) CrP - supplementation of mineral product at 113 g animal/d containing Chromium Propionate (0.4% animal/d, KemTRACE, Kemin Industries; n = 471 cows; 16 experimental units). Mineral supplementation was offered starting at 45 d pre-breeding, during the breeding season, and until weaning for a total of approximately 150 d. Cows were enrolled in a fixed-time artificial insemination (TAI) using the 7-d CO-Synch+CIDR protocol followed by natural service with clean-up bulls 7 d after TAI, for a 70-d total breeding season. Pregnancy diagnosis was performed by ultrasonography 55 d after TAI and again approximately 40 d after the end of the breeding season. Cow body weight (BW) and BCS were recorded at the beginning of the experiment (d -45), at the initiation of the TAI protocol (d -10), at each pregnancy diagnosis (d 55 and 110), and at weaning (d 150). Mineral intake was estimated based on the difference in weight between offered mineral and refusals. Data were analyzed using the GLIMMIX, for binomial data, and MIXED, for continuous data, procedures of SAS. Cow initial BW and DPP were similar (P &amp;gt; 0.10) between treatments (584 ± 198 kg and 78 ± 3 d, respectively). Estimated mineral intake was similar (P = 0.52) between treatments (119.6 ± 10.3 g and 124.5 ± 10.4 g animal/d, for Control and CrP, respectively). Supplementation of CrP did not influence estrus expression (58.3% vs 61.0% ± 2.5 %; P = 0.45), TAI pregnancy rates (63.1% vs 60.1 % ± 2.9 %; P = 0.56), or final breeding season pregnancy rates (94.2% vs 94.7% ± 2.9 %; P = 0.86), for CrP and Control, respectively. Chromium Propionate supplementation did not affect (P &amp;gt; 0.10) final cow BCS and BW (5.2 ± 0.03; 562.9 ± 169.93 kg). In conclusion, Chromium Propionate supplementation delivered via an oral mineral supplement during the pre-breeding and breeding periods did not influence reproductive performance and changes in BW and BCS of beef cows.

Maternal protein supplementation during mid-gestation improves offspring performance and metabolism in beef cows.

This study examined the impact of maternal protein supplementation during mid-gestation on offspring, considering potential sex-related effects. Forty-three pregnant purebred Tabapuã beef cows (20 female and 23 male fetuses) were collectively managed in a pasture until 100 d of gestation. From 100 to 200 d of gestation, they were randomly assigned to the restricted group [(RES) - basal diet (75% corn silage + 25% sugar cane bagasse + mineral mixture); n = 24] or control group [(CON) - same basal diet + based-plant supplement [40% of crude protein, 3.5g/kg of body weight (BW); n = 19]. From 200 d of gestation until parturition, all cows were equally fed corn silage and mineral mixture. During the cow-calf phase, cows and their calves were maintained in a pasture area. After weaning, calves were individually housed and evaluated during the backgrounding (255 to 320 d), growing 1 (321 to 381 d), and growing 2 (382 to 445 d) phases. Offspring's blood samples were collected at 210 and 445 d of age. Samples of skeletal muscle tissue were collected through biopsies at 7, 30, and 445 d of age. Muscle tissue samples were subjected to reverse-transcription quantitative polymerase chain reaction analysis. Prenatal treatment and offspring's sex (when pertinent) were considered fixed effects. The significance level was set at 5%. At mid-gestation, cows supplemented with protein reached 98% and 92% of their protein and energy requirements, while nonsupplemented cows attained only 30% and 50% of these requirements, respectively. The RES offspring were lighter at birth (27 vs. 31kg), weaning (197 vs. 214kg), and 445 d of age (398 vs. 429kg) (P ≤ 0.05). The CON calves had greater (P < 0.05) morphometric measurements overall. The CON offspring had ~26% greater muscle fiber area (P ≤ 0.01). There was a trend (P = 0.06) for a greater Mechanistic target of rapamycin kinase mRNA expression in the Longissimus thoracis in the CON group at 7 d of age. The Myogenic differentiation 1 expression was greater (P = 0.02) in RES-females. Upregulation of Carnitine palmitoyltransferase 2 was observed in RES offspring at 445 d (P = 0.04). Expression of Fatty acid binding protein 4 (P < 0.001), Peroxisome proliferator-activated receptor gamma (P < 0.001), and Stearoyl-Coenzyme A desaturase (P < 0.001) was upregulated in CON-females. Therefore, protein supplementation during gestation enhances offspring growth and promotes favorable responses to lipogenesis, particularly in females.

Performance and ruminal fermentation of second-trimester pregnant beef cows fed short-season high-moisture corn stover or barley greenfeed during winter in western Canada

This study evaluated performance and ruminal fermentation for cows fed short-season high-moisture shelled corn stover with corn dried distillers’ grains with solubles (COR) or barley greenfeed (BAR) that was either swathed (S-COR; S-BAR; Experiment 1) or baled (B-COR; B-BAR; Experiment 2) as winter-feeding systems. In Experiment 1, cows were randomly assigned to S-COR or S-BAR and fed for 52 days in the fields where crops were grown. Body weight (BW), subcutaneous rib and rump fat, and body condition score (BCS) were measured, with no differences detected between treatments ( P &gt; 0.05). However, S-COR had a lower estimated dry matter intake (DMI) than S-BAR ( P ≤ 0.03). In Experiment 2, cows were assigned to B-COR or B-BAR for 42 days and fed in field paddocks. Cows fed B-COR had less ( P ≤ 0.01) DMI, final BW, rib fat, rump fat, and BCS than B-BAR, with no differences ( P &gt; 0.05) for ruminal pH. Total SCFA concentration was greater ( P ≤ 0.05) on day 21 for B-BAR than B-COR, but not on day 42. Under western Canadian conditions, COR may reduce DMI and the performance of pregnant cows, suggesting that additional preservation and supplementation strategies should be investigated.

PSIX-22 Performance, Digestibility, and Blood Parameters in Pregnant Beef Cows Fed Total Mixed Ration Silages

Abstract The aim of this study was to investigate the effects of two total mixed ration (TMR) silages (low and high rumen undegradable protein; RUP) on digestibility, blood parameters, and performance in pregnant beef cows. Thirty-three mid-gestation (~130 d of gestation) Tabapua beef cows were randomly assigned to 1 of 2 treatments: 1) a TMR silage containing Brachiaria grass, soybean hulls, urea, and mineral mix (low RUP; n = 16) or 2) a TMR silage containing Brachiaria grass, DDG, and mineral mix (high RUP; n = 17). The concentration of A1 fraction was, on average, 12.9% and 34.0% of N in low and high RUP silages, respectively. A preservative with a blend of organic acids, surfactants, and activated propionates was applied in both silages. Pressed bag silos were used to conserve silages for 7 wk. Cows were housed in individual pens for 100 d. During a 4-d digestion period (at 50 d of housing), fecal samples were collected for measurement of nutrient digestibility using undigested neutral detergent fiber as a marker. Blood parameters were collected at the last day of housing. Statistical analysis of experimental data was performed using the GLM procedure of SAS 9.4. Diet, calf sex (male or female), and interactions between these factors were considered fixed effects. No differences were obtained for initial BW. High RUP diet showed greater final BW (P = 0.0004) and ADG (P = 0.0003). Cows fed high RUP gained 50 g/d, while cows fed low RUP diet lost 445 g/d. Dry matter intake was greater by 23% (P &amp;lt; 0.0001) in cows consuming high RUP silage. Dry matter, CP, and NDF digestibility did not differ between treatments. Regarding blood parameters, no differences were observed for glucose at 0 h and 4 h post-feeding. Plasma urea at 0 h post-feeding was greater in cows fed low RUP silage (P = 0.0003). However, no differences were observed for plasma urea at 4 h post-feeding. The plasma concentrations of non-esterified fatty acids (P = 0.017) and beta-hydroxy-butyric acid (P = 0.002) were greater in cows consuming low RUP diet. Overall, feeding pregnant cows during mid-gestation with TMR silage containing high RUP promotes greater performance.

171 Supplementing Ca Salts of Soybean Oil Via Low-Moisture Molasses-Based Blocks to Improve Reproductive Performance and Overall Productivity of Beef Cows

Abstract This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckling multiparous Angus-influenced cows (n = 554) were assigned to a fixed-time artificial insemination (AI) protocol (day -10 to 0) followed by natural service (day 15 to 70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25% (as-fed basis) of CSSO or ground corn (CON) from day -10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Groups were enrolled in an estrus-synchronization + fixed-time AI protocol from day -10 to 0 (AI occurred on day 0) of the experiment and beginning 15 days after AI cows were exposed to mature Angus bulls for 55 d. Pregnancy status was verified on day 55 and 100 of the experiment, and cows that gave birth during the initial two weeks were considered pregnant to fixed-time AI. Calf birthdate and weight was recorded during the subsequent breeding season. All calves were weaned at the same time, and a calf BW and age were recorded. Blood samples were also collected from a subsample of cows on days -10, 0 (fixed-time AI), and 55 (pregnancy diagnosis). All data were analyzed using group as the experimental unit and Satterthwaite approximation to determine the denominator df for the tests of fixed effects. Quantitative data were analyzed with the MIXED procedure of SAS, and binary data analyzed with the GLIMMIX procedure of SAS with a binomial distribution and logit link function. Data were analyzed with group (treatment × location), cow(group), and location as random variables. Significance was set at P ≤ 0.05 and tendencies were determined if P &amp;gt; 0.05 and ≤ 0.10. Cows receiving CSSO had greater (P &amp;lt; 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3%), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04%), which also calved earlier during the calving season (treatment × week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4%), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle.

293 Impact of Late Embryonic and Early Fetal Mortality on Overall Productivity of Suckled Beef Cows

Abstract The objective of this study was to evaluate the effect of late embryonic and early fetal mortality (LEEFM) on the performance of beef cows exposed to fixed-timed artificial insemination (TAI). Postpartum cows (n = 207) from three locations were exposed to a 7-d CO-Synch+CIDR protocol followed by TAI (day 0) and natural service breeding starting 14 days after TAI. Two pregnancy diagnoses were performed on days 29 and 100 and cows were classified as: 1) Maintained (MAINT): cows were pregnant on day 29 and the same pregnancy was confirmed on day 100; 2) LEEFM: cows were diagnosed as pregnant on day 29 but non-pregnant or pregnant by natural service on day 100; and 3) Non-pregnant (NP): cows were diagnosed as non-pregnant to TAI on both days 29 and 100. Cows were evaluated until calves that were a product of the breeding season described herein were weaned. Final pregnancy rates were decreased (P &amp;lt; 0.01) for LEEFM compared with MAINT and NP. Calving (P &amp;lt; 0.01) and weaning rates (P &amp;lt; 0.01) were also decreased for LEEFM compared with MAINT and NP. Average calving day was decreased (P &amp;lt; 0.01) in MAINT cows compared with both NP and LEEFM; however, no differences were observed between NP and LEEFM (P = 0.46). Weaning weight was increased (P ≤ 0.05) for MAINT compared with both NP and LEEFM; however, there were no differences between NP and LEEFM ( P = 0.52). Cows that experienced LEEFM had decreased (P &amp;lt; 0.01) weaning weights per cow exposed compared with both MAINT and NP. In summary, that conceive to TAI and experience LEEFM have decreased performance compared not only to MAINT cows, but also cows that failed to conceive to TAI (NP).

Effect of Vitamin A on Estrous Intensity, Number of Follicles, Follicles Diameter and Pregnancy Rate in Beef Cows

Moringa leaves are used as feed to increase the intensity of estrus. It is assumed that the positive effect on the Moringa leaves is due to the presence of vitamin A. This study aims to see the response of vitamin A as a supplement feed to the reproductive performance of beef cows including estrous intensity, number of follicles, follicle diameter, and pregnancy rate. The research was conducted in September-November 2022 in Lappariaja District, Bone Regency, South Sulawesi Province. 10 cows were used which were divided into 2 groups, each group consisting of 5 cows. Group 1 was the control group without vitamin A and group 2 was supplemented with vitamin A. The data on estrus intensity, number of follicles and pregnancy rate obtained were processed using the Chi-square analysis of 2x2 contingency tables. If the Chi-square test does not meet the requirements, the formula used is the Fisher exact test. While the data on the diameter of the follicles were analyzed by ANOVA test. The results of the research data showed that supplementation of vitamin A had a significant difference (P&lt;0.05) on the intensity of estrous. Meanwhile, the results of the chi-square test on the number of follicles and pregnancy rates (P&gt;0.05) showed that there was no significant difference. Likewise, the ANOVA test on follicle diameter between control cows and vitamin A treated cows did not have a significant difference. Although in this study it did not affect the number of follicles, follicle diameter and pregnancy rate. However, it has an economic effect of 20% on the pregnancy rate in the livestock industry scale.

The Effect of Copper and Zinc Sources on Liver Copper and Zinc Concentrations and Performance of Beef Cows and Suckling Calves.

To determine the influence of the source of gestational and postnatal Cu and Zn supplementation on cow and calf performance, cows (n = 287) were assigned to one of the following two treatments: (1) inorganic (INORG) treatment, in which cows were supplemented with 15 mg of Cu (as CuSO4) and 15 mg of Zn (as ZnSO4) per kg of diet DM, or (2) organic (ORG) treatment, in which cows were supplemented with 15 mg of Cu (as Cu proteinate; Bioplex Cu, Alltech, Inc., Nicholasville, KY, USA) and 15 mg of Zn (as Zn proteinate; Bioplex Zn, Alltech, Inc., Nicholasville, KY, USA) per kg of diet DM. The treatments were initiated prior to breeding and continued throughout gestation until weaning. Liver biopsies were collected for analysis of mineral content. Cow body condition score (BCS), body weight (BW), pregnancy data, calf weaning weight (WW), and antibody response of the calves were recorded. The cows receiving the INORG treatment had a greater BW (p < 0.05) and BCS (p < 0.01) at breeding in Year 2, while the cows on the ORG treatment had a greater (p < 0.05) BW at weaning in Year 2. The cows that received the ORG mineral had improved (p < 0.05) conception rates in Year 1. The calves receiving the ORG treatment had heavier (p < 0.05) 205-day adjusted WWs.

Effects of estradiol cypionate dosage and body condition on reproductive performance of Nellore cattle synchronized for timed-artificial insemination

This experiment was designed to evaluate the effects of increasing doses of estradiol cypionate (ECP) and different body condition score (BCS) on reproductive performance of Bos indicus beef females assigned to a timed-artificial insemination (TAI) management. In this experiment, 1683 Bos indicus Nellore cows were blocked by parity and assigned to receive 1) an intravaginal P4 device (1.9 g of P4) and 2.0 mg of estradiol benzoate on day −11, 12.5 mg (i.m.) of dinoprost tromethamine, 300 IU (i.m.) of equine chorionic gonadotrophin, 0.6 mg (i.m.) of estradiol cypionate and CIDR withdrawal on day −2, followed by TAI on day 0 (n = 849; 0.6ECP) or 2) the same synchronization protocol with 1.0 mg of ECP on day −2 (n = 834; 1.0ECP). In both treatments, estrus expression was measured between days −2 and 0. Body condition score (BCS) was evaluated on days −11, 31, and 71 of the experiment and the BCS variation (Δ) was also determined between these timepoints. Transrectal ultrasonography was performed on days 31, 71, and 111 for pregnancy rate determination. All binary data were analyzed using cow as the experimental unit with GLIMMIX, whereas continuous variables were analyzed with the MIXED procedure of SAS. No treatment effects were observed on estrus expression rate. Treatment × BCS interactions were observed for pregnancy rates in all time points (days 31, 71, and 111), as 1.0ECP cows with a LOW BCS also had a greater P/AI than cows assigned to 0.6ECP. In summary, increasing the dose of ECP benefited the reproductive performance of Nellore beef cows with a reduced BCS (≤2.75), whereas no benefits were seen when the BCS was considered adequate (>2.75).

23 Comparison of Whole Cottonseed to a Traditional Supplement (20% Breeder Cubes) in Commercial Beef Cows: Impacts on Animal Performance, Metabolites, and Methane Emissions

Abstract The objective was to compare whole cottonseed (WCS) with a more traditional supplement (20% breeder cube; BC) to determine the impacts on animal performance, metabolites, and methane emissions in beef cows. Cows (n = 24) were assigned to 1 of 2 experimental treatments (BC vs. WCS) based on age and body weight (BW). Supplements were fed individually at 0.9, 1.8, or 2.7 kg per day, resulting in 12 animals per supplement treatment and 4 animals per supplementation level within treatment. Two additional cows served as negative controls. Cows were fed 4 days per week, with supplementation levels being prorated at 1.6, 3.2, and 4.8 kg per feeding. Data collection occurred in 28-day intervals through d 84, with a final collection on d 99 after all cows finished calving. An amount fed per d × d interaction for BW change (P = 0.001) was detected. Cattle that were not supplemented (control) or received 0.9 kg per day lost more BW than cows that received 1.8 or 2.7 kg of supplement per day. There was a body condition score (BCS) change interaction for amount fed per d × d (P = 0.009). There was an amount fed per d × d interaction for back fat thickness (BFT; P = 0.02), and a tendency for an effect of amount fed per day on BFT (P = 0.07). There was a tendency for an amount fed per d × d interaction for fecal score (FS; P = 0.09) indicating that cattle receiving different amounts of supplement had varying trends in FS over time. A day effect was also observed for fecal score (P = 0.00003). There were no interactions (P ≥ 0.55), effect of treatment (P = 0.85), or effect of amount fed per d (P = 0.45) for fecal pH. A treatment × amount fed per d × d interaction for plasma glucose concentrations (P = 0.04) was detected. An amount fed per d × d interaction was detected for plasma lactate concentrations (P = 0.01) indicating that cattle receiving different amounts of supplement had different trends in lactate concentrations over time. An effect of amount fed per d on plasma lactate concentrations (P = 0.05) was also observed. A tendency for an amount fed per d × d interaction for plasma urea nitrogen (PUN; P = 0.06) was observed indicating that cattle receiving different amounts of supplement had varying trends in PUN over time. No treatment effect on methane emissions was observed between cows consuming BC and WCS (P = 0.68). This experiment suggests that the supplementation of BC or WCS had minimal impacts on performance, metabolites, or methane emissions, but some interactions existed between supplementation source or level and day.

Supplementing Ca salts of soybean oil via low-moisture molasses-based blocks to improve reproductive performance and overall productivity of beef cows

This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckled multiparous Angus-influenced cows were assigned to a fixed-time artificial insemination (AI) protocol (day −10 to 0) followed by natural service (day 15–70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25 % (as-fed basis) of CSSO or ground corn (CON) from day − 10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Cows receiving CSSO had greater (P < 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3 %), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04 %), which also calved earlier during the calving season (treatment × week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4 %), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle.

Effects of 3-day versus 9-day whole-plant corn allocation and hay supplementation on performance, grazing preference, and ruminal fermentation of beef cows

This study was designed to evaluate the effects of a 3-d vs. 9-d whole-plant corn allocation period and hay supplementation on performance, grazing prefer- ence, and ruminal fermentation of beef cows. Whole-plant corn grazing with beef cows was managed during the winters of 2015 to 2016 (yr 1) and 2016 to 2017 (yr 2). Ninety-six Angus- based crossbred cows, including an additional 16 ruminal- ly cannulated cows for a total of 112 head, were allocated in 4 replicated systems for 84 and 88 d in yr 1 and 2, respectively. A completely randomized block design with a 2 × 2 factorial arrangement of treatments was used: hay supplement or no hay supplement, with 3-d or 9-d alloca- tion period of corn forage. Cow body weight, average daily gain, body condition score, rib fat, and rump fat were not affected by supplemental hay, allocation period, or their interaction. Cows fed no hay had greater corn intake than cows fed hay. Supplemental hay resulted in decreased grazing preference for stem, husk, and leaf. Al- location period affected grazing preference for husk. Mean ruminal pH, maximum pH, and duration and area (pH × min) that ruminal pH was <5.5 were not affected by supplemental hay, allocation period, or their interaction. Total short-chain fatty acid concentrations and molar pro- portions of acetate, butyrate, isobutyrate, and valerate and ammonia concentration were not affected by treat- ment. However, supplemental hay decreased the molar proportion of proprionate compared with that of cows not provided supplemental hay. An interaction was observed where cows fed no supplemental hay and cows with a 9-d allocation period had a greater molar proportion of isova- lerate compared with cows fed hay and cows with a 3-d allocation period, respectively. Cow performance was not affected by hay supplementation nor allocation period. However, hay supplementation mitigated low ru- men pH risk and fecal starch loss and may reduce the risk of acidosis when grazing whole-plant corn with beef cows.