Pregnant Cows Research Articles

Stress Can Induce Bovine Alpha-Herpesvirus 1 (BoHV-1) Reactivation from Latency

Bovine alpha-herpesvirus 1 (BoHV-1) is a significant problem for the cattle industry, in part because the virus establishes latency, and stressful stimuli increase the incidence of reactivation from latency. Sensory neurons in trigeminal ganglia and unknown cells in pharyngeal tonsils are importantsites for latency. Reactivation from latency can lead to reproductive problems in pregnant cows, virus transmission to young calves, suppression of immune responses, and bacterial pneumonia. BoHV-1 is also a significant cofactor in bovine respiratory disease (BRD). Stress, as mimicked by the synthetic corticosteroid dexamethasone, reproducibly initiates reactivation from latency. Stress-mediated activation of the glucocorticoid receptor (GR) stimulates viral replication and transactivation of viral promoters that drive the expression of infected cell protein 0 (bICP0) and bICP4. Notably, GR and Krüppel-like factor 15 (KLF15) form a feed-forward transcription loop that cooperatively transactivates immediate early transcription unit 1 (IEtu1 promoter). Two pioneer transcription factors, GR and KLF4, cooperatively transactivate the bICP0 early promoter. Pioneer transcription factors bind silent viral heterochromatin, remodel chromatin, and activate gene expression. Thus, wepredict that these novel transcription factors mediate early stages of BoHV-1 reactivation from latency.

Влияние на климатичните промени върху хематологичния и биохимичен статус на стадо крави от порода Лимузин в средата на два последователни пасищни сезона

The aim of the present study was to evaluate the status in the red and white blood count, together with the values of some enzymes and metabolites - ALT, AST, ALP, serum iron and glucose in selected animals from a herd of Limousine beef cattle in the middle of two consecutive grazing seasons, with large differences in the average daily temperature, the amount and distribution of precipitation and of the quantity and quality of the grass at the end of its vegetation. The study was conducted in the experimental base “Zlatusha” of the IAS-Kostinbrod with 15 pregnant cows equalized by BCS and age, from which blood samples were taken in July, 2022 and 2023, by venipuncture of the tail vein. The analysis of hematological indicators in whole blood was performed with a 5-Part-Diff Automated Hematology Analyzer URIT-5160, and the analysis of biochemical indicators - in plasma extracted from it with a Semi-automatic Biochemical Analyzer BTS-350. Results are expressed as mean values ± S.E.M. and were analyzed statistically by the analysis of variance (ANOVA) method. Although there was almost no difference in the levels of hematocrit and the number of erythrocytes in the middle of two grazing seasons, in July, 2022, the studied cows had a significantly higher level of hemoglobin than in July, 2023 (P<0.001), which reflected also on the significance of the difference in mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) – also at P<0.001. There were no significant differences in leukocyte counts and leukocyte subpopulations and in iron and glucose concentrations in the middle of two consecutive years. ALT and AST enzyme activities were significantly lower (P<0.05), and ALP activity was significantly higher in July, 2022 (P<0.01).

Association of FSHR gene polymorphism with fertility of Holstein cows

Relevance. The view of the mechanisms of hormonal regulation of the ovarian cycle of cows has allowed the development of a large number of synchronization programs. An active search is underway for biomarkers related to the fertility of cows, as well as to identify animals with a high ovarian response to the injection of exogenous gonadotropins. The aim of the work is to study the polymorphism of the FSHR gene and its association with reproduction indicators in black-and-white Holstein dairy cows.Results. Based on the results of genotyping cows (n = 128) using the FSHR gene, the frequency of occurrence of the CC genotype was determined at the level of 0.601, the CG genotype — 0.360, GG — 0.031. It was found that for productive insemination, animals with the CG genotype require fewer inseminations. At the same age, the frequency of insemination of heifers with the CG genotype was 1.43, with the CC genotype — 1.60. After the first calving, the animals with the CG genotype responded more actively to hormonal stimulation in the postpartum period. The interval from the first to fruitful insemination in cows with the CG genotype was 34.7 days, in cows with the CC genotype — 57.2 days (p < 0.05). The number of pregnant cows with the CG genotype re-inseminated after natural hunting was 2.1 times higher than the number of cows with the CC genotype (66.7% and 31.2%). It is assumed that exogenous hormone injection has a stimulating effect on the hypothalamus-pituitary-gonad system in cows with the CG genotype.

Impact of Feed Bunk Space on the Prevalence of Torsion and Foreleg Distal Asymmetry in Holstein Cows.

Leg torsion and distal asymmetry (LTDA) among cows reared on intensive farms in the Comarca Lagunera region of northern Mexico may be indicative of underlying health concerns. To ascertain whether the incidence of LTDA is associated with trough measurements and with productive, reproductive, and disease variables, the prevalence of LTDA was determined in lactating dairy cows. The data were derived from two intensive dairy farms in northern Mexico (G60: 2043 cows in 13 pens with 142.0 m of linear feed bunk space and 65.0 m of pen depth; G100: 2227 cows in 12 pens with 215.0 m of linear feed bunk space and 49.0 m of pen depth). The cows were observed over the course of a week to identify any macroscopic lesions indicative of LTDA. Cows exhibiting lesions were assigned a value of "1", while those without lesions were assigned a value of "0". Furthermore, data regarding other limb diseases (LDs) were collected and subjected to analysis. A comparison was conducted to ascertain the impact of reproductive, productive, and feed bunk size variables on the prevalence of LTDA and other LDs. To ascertain the prevalence of LTDA and LDs, a chi-squared test was employed. The prevalence of LTDA was found to be 27.6% (G60: 31.4%, G100: 22.4%). No association was identified between LTDA and the variables included in the study. However, a correlation was identified between LDs and the following variables: total width, distance from the edge, width from the feed bunk to the tramp, and the presence of a manure crust on the walls. Principal component analysis (PCA) was conducted to examine the correlation between LDs and various factors at the farm and pen levels. The findings indicated that the distance from the feed bunk to the trough, the presence of manure crusts on the walls, and the breeding time were associated with LDs in G100, as well as in three of the twelve pens (302, 306, and 308) within G100. The findings suggest that the prevalence of LDs is associated with an increase in the width of the feed bunk and the width of the manure crust on the walls, particularly in pregnant cows. The results permit the conclusion that LTDA and LDs are associated with the measurements of the feed bunks, the absence of manure cleaning of the feed bunks, and gestation. This association gives rise to significant health issues for Holstein cows on these farms, with more than one in four cows affected. To reduce the prevalence of LTDA in lactating dairy cows, it is recommended that the standard measurements for feed bunk design be adhered to. This will reduce the prevalence of LTDA and LDs, promote the cleaning protocols to avoid the accumulation of manure crusts, and facilitate close monitoring of pregnant cows, thereby alleviating the impacts of these foot pathologies on animal welfare.

Study on the feasibility of using livestock blood as a fetal bovine serum substitute for cultured meat.

Fetal bovine serum (FBS) accounts for the largest portion of the cost of cultured meat production or cell culture experiments and is highly controversial in terms of animal welfare because it is taken from the fetus of a pregnant cow during slaughtering. Nevertheless, FBS is the most important supplement in the cell culture manufacturing process. This study aimed to develop an FBS substitute from slaughterhouse waste blood to reduce the cost of FBS in cultured meat production through various experiments. Our study successfully demonstrated that adult livestock blood obtained from slaughterhouses can effectively replace FBS. Our substitute, when cultured with bovine myosatellite cells, demonstrated cell growth that was either equivalent to or superior to that of commercial FBS. In the process of muscle generation through differentiation, the substitutes from bovine and chicken formed 70%-75% more bovine muscle compared to the control group using FBS. Furthermore, using the FBS substitute can reduce cell culture costs by approximately 61% compared to using commercial FBS. Therefore, the groundbreaking FBS substitute will not only contribute to the development of technology to mass-produce cultured meat using livestock byproducts but will also lower the production cost of media for experimental cell culture or vaccine production.

Perineal hernia in a pregnant Angus heifer (Bos taurus)

AbstractThis case report details a perineal hernia in a 3‐year‐old Angus heifer in late gestation. The heifer had a gradually increasing swelling of the perineal region since 2 weeks. Upon palpation, the swelling was painless, hard and non‐reducible. Ultrasonographic examination revealed a hernial sac enclosing the non‐pregnant horn of the uterus, filled with homogenous hypoechoic fluid. Based on the anamnesis and clinical examination, a tentative diagnosis of perineal herniation was made. Considering the deteriorating clinical condition of the cow and the possible risk of dystocia, the viable calf was delivered by Caesarean section. The cow recovered with a reducible hernial sac, which was decided not to correct surgically due to its large size. After 7 days, the cow showed no further complications and was discharged. In conclusion, although rare, a perineal hernia involving the uterus should be considered in the differential diagnosis of perineal swellings in pregnant cows.

Evaluating the suitability of placental bovine explants for ex vivo modelling of host-pathogen interactions in Neospora caninum infections

Bovine abortions, often caused by infectious agents like Neospora caninum, inflict substantial economic losses. Studying host-pathogen interactions in pregnant cows is challenging, and existing cell cultures lack the intricate complexity of real tissues. To bridge the gap between in vitro and in vivo models, we explored the use of cryopreserved bovine placental explants. Building upon our successful development of protocols for obtaining, culturing, and cryopreserving sheep placental explants, we applied these methods to bovine tissues. Here, we compared fresh and cryopreserved bovine explants, evaluating their integrity and functionality over culture time. Additionally, we investigated their susceptibility to N. caninum infection. Our findings revealed that bovine explants deteriorate faster in culture compared to sheep explants, exhibiting diminished viability and function. Cryopreservation further exacerbated this deterioration. While fresh explants were successfully infected with N. caninum, parasite replication was limited. Notably, cryopreservation reduced infection efficiency. This pioneering work paves the way for developing ex vivo models to study reproductive pathogens in cattle. However, further optimization of the model is essential. These improved models will have the potential to significantly reduce the reliance on animals in research.

Metabolic profile of prepartum dairy cows and its influence on the immediate postpartum period, colostrum quality and passive immunity transference

The objective of this study was to evaluate which biochemical markers in the prepartum period of dairy cows influence the immediate postpartum period, the quality of colostrum, and the passive immunity transference in the calves. The experiment was performed on a commercial dairy farm with 52 pregnant multiparous Holstein cows. Animals that gave birth to twins or males were discarded from the experiment. On days -20 of the expected calving date and 24hours after calving, blood collections, body condition score assessments, and animals weighing were performed. Blood samples from calves were performed 24hours after colostrum intake. Calf plasma was used to estimate the passive immunity transfer by % brix and total plasma proteins (TPP). In the principal component analysis, it was shown that postpartum NEFA and BHBA was higher in cows with higher prepartum urinary pH and Ca lower prepartum. The cows with the highest NEFA and BHBA in pre and postpartum were the ones that had the lowest % brix in the colostrum. The % brix of the cow’s colostrum directly influenced the % brix and TPP of the calves. The NEFA in the cows prepartum negatively influenced the markers of immunity, the higher the NEFA, the lower the % brix of the cows’ colostrum, % brix of the calves, and TPP. In multivariate regression analyses it was shown that pre-calving NEFA was the marker that most influenced post-calving cow markers and calf % brix, along with colostrum time and % brix of the colostrum (P= 0.0092; r2= 0.83). Cows with higher values NEFA in the prepartum had lower calcemic in the immediate postpartum period. Prepartum NEFA was the marker that most influenced the cows’ immediate postpartum period, being directly related to Ca serum, and also to the passive immunity transference.

A feasibility study on predicting cow calving time over 40 h in advance using heart rate and financial technical indicators

In dairy farming, the uncertainty of cow calving date often imposes waiting costs for days on farmers. Improving the accuracy of calving date prediction would mitigate these costs, specifically before a few days of the event. We monitored and analyzed the heart rate patterns of eight pregnant cows in the days leading up to calving using a dedicated monitoring device. We decomposed the heart rate data into three distinct components: trend, daily cycle, and the remainder, and discovered that the heart rate trend exhibited a sharp decline more than 40 h before the calving event via the trend turning point. To detect the turning point, we applied common financial technical indicators traditionally used to identify turning points of asset prices in trading markets for the extracted heart rate trend. This study remains a feasibility study because of the limited observations, but it indicates that these indicators can effectively capture the trend’s turning point in real time, offering a promising approach for enhanced calving prediction. In addition to discussing the practical implications for cow management, we also contemplate the broader utility of these technical indicators in the context of various dynamic scientific data analyses.

PSVI-22 Effects of supplementation of beef cows during gestation on progeny backgrounding frame size and performance

Abstract The implications of supplementation during gestation on growth and efficiency of offspring have gained interest worldwide. The hypothesis of this study was that supplementation of cows during gestation results in favorable progeny growth and nutrient utilization. Our objectives were to assess the impacts of providing supplementation to pregnant beef cows during the dry grazing period on progeny backgrounding performance. During a 2-yr period, Tabapuã cows (n = 36) were managed on Brachiaria pastures, which were assigned to 1 of 3 treatments as follows: no application of N on pasture and cows supplemented with mineral mix (CON), application of 165 kg of Nּ ha-1ּ yr-1 and cows supplemented with a commercial product containing 40% of CP, macro and micro minerals, and vitamins (SUP), and application of 165 kg of Nּ ha-1ּ yr-1 and cows supplemented with grass silage (GS). At the beginning of the dry period, the commercial supplement and silage were fed for 140 d (from 116 ± 27 to 256 ± 27 d of gestation). The mineral mix was offered all year round. Bull (n = 18 in yr 1 and 12 in yr 2) and heifer progeny (n = 13 in yr 1 and 17 in yr 2) were weaned with average age of 203 ± 18 d in yr 1 and 229 ± 15 d in yr 2. After weaning, progeny were weighed and allocated in individual pens and adapted to a growing diet over 90 in yr 1 and 89 d in yr 2. For both years, rations were formulated to provide 0.9 kg/d (Dietary NEm = 1.68 Mcal/kg and dietary Neg = 1.07 Mcal/kg, on average). The PROC MIXED procedure of SAS was used to analyze all variables. The statistical model included supplementation program as a fixed effect and sex (male or female) as a random variable. Initial BW, weaning age, estimated progeny difference, and d on feed were included as covariates. No differences were obtained for initial BW, final BW, ADG, DM intake, and G:F. Frame size (e.g., heart girth, hip height) was also unaffected by dam supplementation. Overall, supplementing pregnant beef cows, during the dry grazing period, with a commercial supplement or silage does not affect progeny performance during backgrounding.

PSX-2 Productive performance of Raramuri Criollo, Angus x Raramuri Criollo and Hereford x Angus cows in a low-input cow-calf system in northern Mexico

Abstract Raramuri Criollo cattle (RC), a local heritage breed in the Chihuahua state of Mexico, are highly rustic and well-adapted animals that can contribute to cow productivity in a low-input cow-calf production system. The aim was to evaluate traits related to productive performance of purebred RC, Angus x RC (AC) and Hereford x Angus (HA) cows. Each cow breed group was randomly assigned to one of three pastures within each of two mountains dominant exposures and evaluated during 2022 and 2023 at Rancho Teseachi (28◦48′ N, 107◦25′ W) belonging to Universidad Autonoma de Chihuahua. The six grazing pastures ranged from 263 to 400 ha, with similar slope, altitude and water sources characteristics. The stocking rate was moderate (forage utilization <50%). Forage biomass availability for the period of use was sampled in October, and stocking rate adjusted accordingly in March. RC cows were bred with RC bulls, and AC and HA with Angus bulls. The breeding season was from September to November, and pregnancy diagnosis at mid-January. Non-pregnant cows were replaced by pregnant cows from other pastures of the same farm. Feed supplementation was limited in 2022 and according to nutritional requirements in 2023. Evaluated variables included calf birth (BW) and weaning weight adjusted (WW) to the average age at weaning (190 d in 2022 and 165 d in 2023); body condition score (BCS 1 to 9), cow body weight (CBW) at the beginning of the breeding season, as well as body weight of calf weaned by unit of cow weight (WW/CBW), and pregnancy rate (PR). A general linear model with fixed effects of breed group, sex, dominant exposure of mountains, their interaction, cow age subclass (Young, 4 yr; Middle, 5 to 8 yr; Adult, > 9 yr) and Julian date at calving as a covariate was adjusted using PROC GLM of SAS for continuous, normally distributed variables, and PROC CATMOD for pregnancy rate, leaving out sex and interaction effects. Means of BW and WW on calves from AC and HA cows were greater (P < 0.5) than those from RC cows in both years (Table 1). In 2022, the mean CBW of HA was greater (P < 0.5) than for AC, and this greater (P < 0.5) than for RC cows; BCS was greater for AC than for HA and RC, and PR lower (P < 0.5) for HA than for AC and RC. In 2023, there was no difference in CBW between AC and HA; BCS was similar (P > 0.05) among the three groups; and PR was the lowest (P < 0.5) for HA. The AC cows had the greatest WW/CBW mean (P < 0.5) in both years. Overall, using AC cows resulted on a combination of traits that outperformed on general productivity in the evaluated production system.

PSLBI-12 Screening and isolation of Fusobacterium necrophorum and Fusobacterium varium from seminal, and vagino-uterine microbiota of healthy cattle and sheep

Abstract Fusobacteria necrophorum is an important opportunistic bacterial pathogen associated with liver abscesses, foot rot, necrotic laryngitis and endometritis in both dairy and beef cattle. Recently, we identified F. necrophorum as one of the taxa in the uterine microbiota that are positively associated with pregnancy outcome in beef cows, and that Fusobacterium was identified as the most dominant genus in the bovine seminal microbiota. These findings indicate that Fusobacterium spp. may have a role in reproductive health and cattle fertility. Our objectives were to detect and isolate the F. necrophorum subsp necrophorum (FNN), F. necrophorum subsp. funduliforme (FNF) and F. varium (FV) in seminal, vaginal and uterine microbial ecosystems as well as fetal samples by culture and real-time PCR (qPCR) methods. The qPCR was performed on the DNA (n = 215) extracted from bull semen (n = 37), ram semen (n = 100), and vaginal (n = 25) and uterine swabs (n = 32), caruncles (n = 9), allantoic fluid (n = 6), and amniotic fluid (n = 6) from pregnant beef cows. The qPCR targeted the hgdA gene, and leukotoxin promoter regions (lktA-n and lktA-f) to detect and quantify FV, FNN and FNF, respectively. Cryopreserved samples (n = 174; 57 bull semen, 10 ram semen, 38 vaginal, and 47 uterine swabs) were cultured to detect and isolate FNN, FBF and FV by direct plating and after culturing in anaerobic peptone-yeast extract broth containing sodium lactate broth with josamycin, vancomycin and norfloxacin for selective enrichment of FN and FV. Also, 28 samples of 6-mo-old bovine fetuses caruncles, allantoic and amniotic fluids, and intestinal tissue) were screened for Fusobacterium species. By qPCR, FNF was detected in 75.7% of bull semen, and 8.0% of vaginal swabs as well as 33.3% of both allantoic fluid and caruncles, but was undetected in ram semen, uterine swabs, and amniotic fluids. Subspecies necrophorum was identified in 37.8% of bull semen, 3% of ram semen, 8.0% of vaginal and 15.6% of uterine 55.6 % of caruncles, 50% of allantoic fluid samples, but was not detected in amniotic fluid samples. Meanwhile FV was only detected in vaginal, uterine swabs and caruncles at 4%, 6.3%, and 11.1%, respectively. The culture method detected FNF in 63.2% of bull semen and 5.3% of vaginal samples, while FNN was identified in 1.8% of bull semen and 2.1% of uterine samples. F. varium was not isolated from any of the samples. Overall, FNF was the most prevalent subspecies present in the seminal microbiome of bulls. Identification of FNN subspecies and FV in seminal, vaginal, and uterine microbiota of healthy cattle, as well as in healthy calf fetus-associated samples suggests potential transfer from bulls to cows and then on to offspring, and potential involvement of the Fusobacterium spp. in cattle fertility.

104 Non-invasive pregnancy diagnosis in Holstein dairy cows using computer vision analysis of thermal images

Abstract Thermal visualization of Holstein dairy cattle skin can be indicative of the pregnancy state (cyclic or pregnant) of the cow by observing the size and shape of skin thermal patterns. However, visual assessment of skin thermal patterns can be subjective and laborious. Further, infrared thermography implementation on-farm requires automated analysis to be feasible for dairy producers. The objectives of this study were to implement a machine learning convolutional neural network (CNN) to detect features in thermal images associated with pregnant (Pregnant) and non-pregnant (Cyclic) and to evaluate the accuracy of pregnancy diagnosis in dairy cows. A total of 938 images from 18 Pregnant cows and 982 images from 18 Cyclic were used to build the CNN model, and 120 images from Pregnant (60 images) and Cyclic (60 images) dairy cows were used to validate the model. Pregnant cows were confirmed to be pregnant 90 d after insemination via transrectal ultrasonography. Cyclic cows were confirmed to be non-pregnant using follicular dynamics and corpora lutea presence via transrectal ultrasonography. Images were recorded using a T620s infrared camera at 640 × 480 (307,200) to train the CNN model and images from an E40 FLIR camera at 320 x 240 (76,800 pixels) were used for the validation test. The CNN model was created using TensorFlow in Google Colab to binary classify images into Pregnant or Cyclic using a single output neuron (1: Pregnant and 0: Cyclic) with different Epochs (10, 25, and 100). The diagnosis accuracy (acc) was 0.72 with a validation accuracy (val_acc) of 0.41 for 10 Epochs, acc 0.76 with val_acc 0.37 for 25 Epochs, and acc 0.80 with val_acc 0.63. The acc and val_acc of the training model and validation test were optimized when using images from the T620s exclusively (Epochs 10: acc = 0.70 and val_acc = 0.64; Epoch 25: acc = 0.74 and val_acc = 0.70; Epoch 100: acc = 0.81 and val_acc = 0.80). Greater resolution of thermal images was proven to increase the accuracy of pregnancy diagnosis (307,200 compared with 76,800 pixels) and the greater number of Epoch used to train the model. Machine learning algorithms can diagnose pregnancy using thermal images with an acceptable evaluation accuracy (> 0.70).

261 Vitamin A administration in pregnant cows or newborn calves: Growth performance and carcass traits

Abstract This study aimed to evaluate the effects of Vitamin A (VA) injection on the growth performance and carcass traits of Nellore × Angus crossbred steers and heifers. For that, the same sire inseminated Nellore cows from two artificial insemination (AI) groups were randomly assigned to one of three treatments at 250 d of gestation: no VA injection (Control); VA injection in pregnant cows at 250 d of gestation (VAcow; 2,000,000 IU single dose); VA injection in newborn calves at birth and 60 d of age (VAcalf; 200,000 IU each dose). Cow-calf pairs were kept in the same paddock, and calves received creep-feeding supplementation from 90 d of age to weaning. After weaning, steers and heifers [n = 36; body weight (BW) 213 ± 25.7 kg] were stratified by treatment and BW and allotted into 16 pens. After 207 d of feeding (77 d of growing diet + 130 d of finishing diet), steers and heifers were slaughtered at a commercial abattoir. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of VA injection, sex, and VA injection*sex interaction. The random effects were animal, AI group, and cow parity. Average daily gain before weaning (P < 0.01) and final BW in the finishing phase were greater (P = 0.04) in VAcow steers compared with heifers from all treatments (Table 1). Vitamin A had a positive impact on weaning BW of male calves and a negative impact on heifers (P < 0.01). There was no treatment difference (P = 0.35) in feedlot average daily gain (ADG), but steers had greater (P = 0.03) ADG compared with heifers. Moreover, VAcow steers had greater dry matter intake (DMI) in the feedlot (P = 0.04) compared with other treatments, and there was no effect of VA on DMI of heifers. On the other hand, feedlot feed efficiency tended to be greater (P = 0.07) in Control steers compared with other treatments, with no VA effect on heifers too. The ribeye area was greater (P = 0.04) in VAcow steers than in Control steers and heifers from all treatments. Intramuscular fat content was greater (P = 0.04) in VAcow steers than in Control and VAcalf steers. However, there was no effect of VA on heifers and VAcow steers. In addition, VAcow treatment tended (P = 0.08) to increase backfat thickness. In conclusion, VA injection in pregnant cows can be a strategy to improve marbling in steers, but there is no effect on intramuscular fat in heifers. Additionally, VA injection in pregnant cows produced intramuscular content in beef of steers, similar to heifers.

391 The impact of trace mineral source on systemic immunological status associated with early embryonic loss in lactating dairy cattle

Abstract Milk production has doubled from 1970 to 2009 but has been associated with a decline in fertility. Around 25% of failed pregnancies in dairy cattle are due to embryonic loss. Mineral bioavailability may affect embryonic retention, so we hypothesized that Zn, Cu, and Mn sources will influence systemic immunological status, which affects early embryonic retention. Holstein cows (n = 58) were randomly assigned to one of two daily oral drench trace mineral (Zn, Cu, and Mn) treatments 30 d before breeding (d -30): 1) Inorganic (ITM) or 2) Metal Methionine Hydroxy Analog Chelate (MMHAC). Before treatments began, cows were assigned to a semen type, beef vs. Holstein, equally, across treatments. All cows underwent a double Ovsynch protocol and were artificially inseminated on d 0. Humoral immunological status was assessed in serum samples taken on d 0 and d 7. Immune activity was quantified via a D2Dx systemic immunity score, which assesses samples for the presence of IgG, IgM, cytokines, and complement proteins. Ultrasonography was utilized for pregnancy confirmation on d 35, classifying cows as pregnant (P) or open. Progesterone analysis from d 21 plasma was used to categorize open cows as either non-pregnant (NP) or early embryonic loss (EEL). Statistical analyses in R Studio were completed, in two models based on pregnancy (P vs EEL and NP vs EEL), to determine the effects of mineral treatment, pregnancy status, semen type, and all interactions on humoral immune status. In the P vs EEL model, there were no effects (P > 0.30) of semen type, mineral treatment, pregnancy status, or any interactions on systemic immunity score on the day of breeding (d 0) or d 7. On d 0, cows provided MMHAC had a systemic immunity score of 0.073 ± 0.008 but were not different (P > 0.34) from ITM cows (0.063 ± 0.006). This trend continued on d 7 with systemic immunity scores of MMHAC cows not differing (P > 0.32) from ITM cows (0.055 ± 0.004 and 0.061 ± 0.003; respectively). There was a tendency (P = 0.10) for the three-way interaction of semen type x pregnancy x treatment to influence the immunity score change from d 0 to d 7. Pregnant cows on ITM treatment bred with beef semen had a positive change in immunity score (0.020 ± 0.0085). Whereas ITM cows bred with Holstein semen that underwent EEL had a negative change (-0.015 ± 0.0085); all other means were intermediate. In the NP vs EEL model, there were no effects (P > 0.14) of semen type, treatment, pregnancy status, or any interactions on systemic immunity score on d 0, d 7, or the change between d 0 and d 7. In summary, trace mineral bioavailability tended to affect systemic immunological status in P vs EEL cows but not in NP vs EEL cows, which may allow for the elucidation of immunological status differences during pregnancy establishment.

26 Trace minerals to improve bull fertility

Abstract Bull fertility is paramount for reproductive success in cow-calf production systems and there are a variety of factors that influence bull fertility. Trace mineral requirements and recommendations have been established for growing and finishing steers, as well as lactating and pregnant cows, yet no specific requirements have been established for young or mature beef bulls. Nonetheless, trace minerals have been shown to have an important role in sexual maturation and semen quality of ruminants. Research performed in rams indicates that zinc deficiency results in reduced testicular development, decreased testicular concentrations of testosterone, and impaired development of seminiferous tubules. Deficiency of Zn has also been reported to negatively impact male fertility in humans, where men diagnosed with infertility responded positively to Zn supplementation. In growing bulls, diets with greater concentrations of organic forms of Zn, Cu, and Mn, tended to result in earlier attainment of puberty compared with control diets containing inorganic minerals. Furthermore, greater liver concentrations of Zn have been negatively correlated with sperm acrosomal damage in growing bulls, based on flow cytometry analyses. More recent research indicates that the use of hydroxichloride-based trace minerals results in greater liver concentrations of Zn and Cu compared with sulfate sources. While evidence indicates that trace mineral status has an important role in bull fertility, further research is required to better understand the contributions of trace minerals to semen quality. In addition, investigating the impact of trace mineral sources with greater bioavailability on semen quality may result in the development of practical recommendations that optimize bull fertility.

428 Influence of melatonin supplementation in pregnant multiparous crossbred beef cows grazing endophyte-infected tall fescue on dam weight, milk yield, and pre-weaning growth of steer calves

Abstract The objective was to evaluate the influence of melatonin supplementation in pregnant beef cattle grazing toxic, endophyte-infected tall fescue (E+) on post-calving dam body weight (BW), milk production, and preweaning growth of steer calves. Multiparous cows were artificially inseminated with sex-sorted semen (Y chromosome-bearing sperm) from a single Red Angus sire and maintained on pastures free from E+ fescue prior to the start of the treatment period. Pregnant cows were assigned to one of three treatment groups with two replications per treatment: non-toxic, novel endophyte-infected (NE+) tall fescue without melatonin supplementation (NE+/NM; n = 15), E+ fescue with melatonin supplementation (E+/M; n = 16), and E+ fescue without melatonin supplementation (E+/NM; n = 18). The treatment period was over 70 d between May and July (d 147 ± 1 to 217 ± 1 of gestation). A commercially available feed was mixed with melatonin (100 µg/kg BW) or without melatonin and hand-fed to each cow daily. At the conclusion of the treatment period (56 ± 18 d before parturition), cattle were moved to a single group and maintained on pastures free from E+ fescue for the remainder of the study. Dams and steer calves were weighed at d 0, 28, 56, 84, 112, 140, and 168 relative to calving (d 0 = calving). Four-hour milk yields on d 28 ± 3 and d 56 ± 3 were used to estimate daily milk volume and weight. Dam and calf BW were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment, time, and the interaction as fixed effects and replicate as random. Calf birth weight, dam milk volume, and dam milk weight were analyzed using the MIXED procedure of SAS with treatment as a fixed effect and replicate as random. On d 28, estimated daily milk volume and weight were decreased (P < 0.05) in E+/NM dams relative to NE+/NM dams. On d 56, estimated daily milk volume and weight were decreased (P < 0.03) in E+/NM and E+/M dams relative to NE+/NM dams. There was an effect of time for dam and calf weights (P < 0.01). There was a treatment by time interaction for calf body weight, with calves born to E+/NM dams having decreased body weight relative to calves born to NE+/NM and E+/M dams from d 112 to d 168 (P = 0.02). There were no other effects of treatment, time, or the interaction (P > 0.05). These data suggest melatonin supplemented to pregnant crossbred multiparous beef cows grazing endophyte-infected tall fescue during mid-late gestation may increase preweaning growth of steer calves.

24 Maternal supplementation with different sources of trace minerals to beef cattle and its effects on postweaning responses of the offspring

Abstract The goal of this trial was to evaluate the effects of different sources of trace minerals on fetal programing and their impact on cow reproductive and postweaning offspring performance until slaughter. Seventy-two non-lactating, pregnant Angus cows [initial body weight (BW) = 637 ± 13 kg; body condition score (BCS) = 5.5 ± 0.07; and age = 6.1 ± 0.57; exposed to artificial insemination (AI) = 54 and bull = 18] were ranked by BW and BCS and assigned to receive a supplement containing: 1) Cu, Mn, and Zn from sulfate source (INR; n = 24), 2) Cu, Mn, and Zn from organic source (ORG; n = 24), or 3) Cu, Mn, and Zn from hydroxychloride source (HXD; n = 24). From d 0 to calving, cows remained on the same pasture and were fed individually three times a week. After calving, pairs were assigned to the general herd management, including inorganic mineral supplementation. Calves were weaned at 6 mo of age and were managed as a single group on a backgrounding period for 85 d. Calf blood samples were collected on d -15, 0, 4, 8, 15, 20, and 28 relative to weaning to evaluate stress-related markers. After this period, calves were fed to finish in a commercial feedyard. Cattle were then harvested, and carcass data were recorded. Though not the focus of this trial, there was a numerical improvement (P = 0.22) in overall subsequent pregnancy rate for the HDX (92.1%) compared with the ING (74.3%) and ORG (75.2%) cows. Also, the HDX had a tendency (P = 0.07) for improvement in liver Cu status compared with the other treatments. At weaning, no treatment differences were detected (P ≥ 0.88) in calf weaning BW and average daily gain from weaning to feedyard receiving. There were no differences (P ≥ 0.22) in the blood stress-related enzymes and metabolites. However, there was a tendency for a decrease in plasma haptoglobin at day 15 post-weaning (P = 0.07) for the calves from HDX supplemented cows relative to other treatments (Figure 1). Which might indicate potential amelioration of inflammation for the calves from cows supplemented with HDX trace minerals during pregnancy. Feedyard growth performance were similar (P ≥ 0.35) across treatments for the offspring (Table 1). No treatment effects were detected (P ≥ 0.17) for carcass traits between treatments (Table 2). Overall, different sources of trace minerals supplemented to late gestating beef cows yield similar effects on offspring performance from weaning and background period until slaughter, whereas a potential amelioration of inflammation was observed in calves born to HDX cows.

255 Awardee Talk: Nutritional management to optimize cow-calf production in Southeast

Abstract Nearly one-half of beef cows in the United States are located in southern states where cow-calf operations predominate. Grazing management in cow-calf systems can be affected by environmental and seasonal conditions, often leading to nutrient deficiency, particularly during late gestation of beef females. Maternal nutrition during the last trimester of gestation can influence offspring development and health, and can be explored to optimize maternal and progeny performance. The objective of this presentation is to share nutritional and management strategies for pregnant beef cows and their long-term effects on offspring growth and physiology. Study 1 investigated the effects of timing of maternal protein supplementation during all last trimester of gestation (LATE84), only the first 42 d of last trimester of gestation (LATE42), or no prepartum supplementation (NOSUP) on offspring pre- and post-weaning performance. At weaning, LATE84 calves were the heaviest, followed by LATE42, and NOSUP (P ≤ 0.05). Steer serum parainfluenza-3 titers were greater (P = 0.03) for LATE42 vs. NOSUP and tended to be greater for LATE84 (P = 0.10) vs. NOSUP steers. Marbling and the proportion of steers grading choice were greater (P ≤ 0.04) for LATE42 vs. NOSUP, and intermediate for LATE84. Study 2 evaluated the effects of frequency of maternal protein supplementation on offspring pre-weaning growth. Cows received the same weekly amount of supplement (7 kg·cow⁻¹·wk⁻¹) but with different frequencies: once a week (1X), three times per week (3X), every day (7X), or no prepartum supplementation (NOSUP) during the last 80 d of gestation. At weaning, calves born from 7X cows were the heaviest (P ≤ 0.05), followed by 3X and 1X, which did not differ between them (P = 0.54), and NOSUP calves were the lightest (P ≤ 0.05). Study 3 evaluated the use of monensin supplementation during the last 77 d of gestation and its impacts on offspring performance. Treatments consisted of no prepartum supplementation (NOSUP), supplementation of dried distillers grains at 1 kg·cow⁻¹·d⁻¹ added with 0 (SUP) or 200 mg/d of monensin (SUPMO). At weaning, SUPMO calves were the heaviest (P ≤ 0.05), SUP intermediate, and NOSUP were the lightest. Experiment 4 consisted of pregnant heifers receiving the supplementation of 1 kg/d of soybean hulls dry matter added (BAC) or not (CON) with a Bacillus-based DFM mixture during late gestation (d 0 to 139) and early lactation (d 139 to 242). Post-weaning body weight gain and indicators of humoral immune response post-vaccination were greater for BAC vs. CON calves (P ≤ 0.05). Therefore, changing the time and frequency of supplementation, and the use of additives and probiotics during late gestation of beef females are effective alternatives to improve offspring pre- and post-weaning growth and immune response.

Infrared thermometry for detecting estrus and pregnancy in Holstein cows

Efficient reproductive management is paramount in enhancing the productivity and welfare of dairy cows. This study investigates the effects of pregnancy status, seasonal variations, and diurnal shifts on the body temperature of different body parts in dairy cows. Using a structured approach, cows were categorized based on pregnancy status (pregnant vs. control) or estrous status (estrous vs. control), season (winter, spring, summer), and time of day (morning, noon, evening). The analysis revealed that pregnancy and estrous statuses significantly affect the body temperature, with pregnant and estrous cows displaying higher temperatures (39.0 ± 0.03 and 38.0 ± 0.06 °C, respectively) than controls (37.1 ± 0.06 °C; p < 0.01). Seasonal impacts were also notable, with the highest temperatures observed in summer (38.3 ± 0.07 °C) followed by spring (38.1 ± 0.09 °C) and winter (37.7 ± 0.06 °C; p < 0.01), indicating a strong environmental influence on physiological responses. Furthermore, diurnal analysis indicated temperature fluctuations throughout the day, peaking at noon (38.1 ± 0.09 °C; p < 0.05) compared to morning and evening. High positive correlations were observed between the measured temperatures in different areas and rectal and vaginal temperatures, suggesting the skin surface is ideal for assessing thermal changes. These findings underscore the critical interplay between an animal's physiological state and external environmental factors in managing dairy cow health and reproduction. The study highlights the potential of non-invasive temperature monitoring as a tool for optimizing reproductive management and underscores the necessity of accounting for environmental and physiological variations in dairy management practices.