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Minimizing interruptions in feed intake during the highly stressful receiving period is critical for lamb performance and animal welfare for lambs arriving from extensively managed operations. The objectives of the study were to evaluate feeder lamb receiving protocols, specifically the effectiveness of hay processing and respiratory vaccine on feed intake, growth performance, feed efficiency and carcass traits on a 107-d feeding trial. Feeder lambs [n = 63; body weight (BW) = 47.6 ± 7.9 kg; wethers n = 46; ewes n = 17; Western white-faced n = 34; black-faced; n = 4; crossbred; n = 25) sourced from 15 WY and CO producers participated in the “Lamb-A-Year” program at the University of Wyoming- Laramie Research and Extension Center. Lambs were randomly sorted into two groups and fed an 8% CP, 61% NDF hay that was either unprocessed or processed (8 cm). One-half of the lambs in each hay processing group were then vaccinated or not vaccinated with a Mannheimia haemolytica Types 1 & 2 and Pasteurella multocida vaccine. Lambs were adapted to electronic feeders (Vytelle, Calgary, AB, CA) for 7 d (7 to 8 lambs/feeder) to record individual daily feed intake for 50 d. During the initial receiving period (d 0 to 14) lambs had ad libitum access to their respective hay treatment. A textured finishing diet was administered from d 15 to 50 (75% corn, 15% soyhulls, 10% lamb grower pellet). From d 51 to 107, lambs were group fed ad libitum the textured finishing diet until slaughter at a commercial abattoir. Hot carcass weight (HCW), 12th rib back fat (RFT), body wall thickness (BWT), and loin muscle area (LMA) carcass data were collected at the abattoir. Data were analyzed as a mixed model with fixed effects of hay treatment, vaccination status, and their interaction with random effects of ranch source and individual animal. The hay treatment x vaccine status interaction was significant (P ≤ 0.03) for RFI. While the ranking changed for RFI when comparing vaccination status, no statistical difference between treatment groups were observed after a Tukey adjustment. Interestingly, the hay treatment x vaccine status interaction was significant (P ≤ 0.01) for BWT. Again, ranking did change; however, no statistical differences were observed after a Tukey adjustment. Under current study conditions, there were no clear effects on dry matter intake (DMI), average daily gain (ADG), HCW, RFT, or LMA (Table 1). The effects of hay processing type and vaccine administration had minimal disruptions on DMI and ADG. Lamb performance may not be influenced by management interventions at the receiving phase. Further research should evaluate producer management prior to weaning and genetic factors that influence overall performance during the backgrounding and feeding phases. [ABSTRACT FROM AUTHOR]

The article focuses on study of materno-placental microbiome of gravid beef cows under feed intake restriction. Topics discussed include existence of reproductive microbiome as evidence in cattle, matured bovine rumen influenced by feed intake restriction, and counts of phyla presented in abundance in mature rumen being impacted.

The rumen microbiome has a critical role in multiple facets of ruminant livestock production. It is well known that the rumen microbiome is integral to animal performance through impacts on feed efficiency, greenhouse gas production, volatile fatty acid production, and numerous aspects of animal health. Therefore, understanding factors that influence the rumen microbiome at various stages of the production cycle and the interactions with other microbial niches and physiological processes is a critical area of research to aid in the goal of improving livestock performance. Our research objectives have focused on 3 primary general areas including 1) to characterize and understand the potential pathways of early gut colonization from conception throughout gestation, 2) implications of varying gestational perturbations on rumen microbiome development and calf performance post-weaning, and 3) understand the connections between the rumen microbiome and the microbiomes of the reproductive tract, blood, and respiratory tract. We hypothesize that strategies to program the rumen microbiome early in life may have lasting impacts on host performance specific to feed efficiency, reproductive fitness, and have implications on high altitude disease. These effects may not be a direct relationship between the rumen microbiome and host response, but rather through a total system level response that has the rumen microbiome as a key player in that cascade. The rumen microbiome has the potential to impact numerous aspects of host performance, as such, it is imperative that research continues to elucidate its role in host physiology and the development of intervention mechanisms to initiate specific responses in the rumen microbiome to improve downstream host response. [ABSTRACT FROM AUTHOR]

Maternal gestational nutrition is known to impact gut physiology and the gut microbiome of offspring early in life; however, it remains unknown if these changes persist later in life. We hypothesized that the impacts of maternal feed restriction in late gestating beef cows on early colonization of the calf gut would impact the rumen microbiome post-weaning. Our objective was to compare the post-weaning rumen microbiome of calves born with feed restricted dams and those born to dams with adequate nutrition. Starting roughly 60 d before expected calving, dams were stratified to either receive 100% of NRC requirements (CON) or 70% intake of NRC requirements (FR) through 28 d post-parturition. Pairs were then moved on to native grass until weaning. Rumen fluid was collected from the calves at the time of weaning (PRE) and after a 70 d backgrounding feed efficiency study (POST). Microbial DNA was isolated and the V4 region of the 16S rRNA was sequenced on the MiSeq platform. Data were analyzed within each time point using QIIME2. Maternal treatment had no impact on alpha diversity (Faith's phylogeny, Shannon's diversity, and Evenness) in the PRE group, but CON calves had greater (q = 0.05) evenness than FR calves in the POST samples. There were differences in composition between CON and FR in the PRE samples (unweighted unifrac q = 0.04; bray-curtis q = 0.03). No differences (q = 0.14) in composition were found in the POST samples. These data indicate that at the time of weaning (PRE) differences in composition existed in CON vs. FR calves, specifically in the rare taxa, but the microbial composition converged by the end of the feeding trial. Interestingly, previous findings in our lab reported differences in alpha and beta diversity 28 d after birth in these calves. Together, these data indicate the potential for long-term impacts of maternal nutrition on the gut microbiome. This coupled with the previously published work where feed efficiency tended to differ between CON and FR, suggests that early perturbations during gestation may have had lasting impacts on gut physiology and subsequent performance in the presence of rumen microbial shifts. [ABSTRACT FROM AUTHOR]

Late feedlot death caused by congestive heart failure has been quantified extensively through epidemiological studies however, these models do not consider losses or gains associated live growth performance, carcass quality, and consumer rejection of meat products. To address these gaps in the literature, we conducted two studies to characterize effects of pulmonary hypertension on four populations of feedlot cattle. In study one, reproductively intact (INT, n = 19), and ovariectomized (OVX, n = 18) yearling Sim-Angus heifers were selected on heart failure risk according to their pulmonary arterial pressure. Heifers were gradually transitioned onto a feedlot ration and fed to an acceptable harvest body composition determined using both 12th rib subcutaneous fat and body weight. Cattle were weighed biweekly and ADG was calculated by regressing body weight by days on feed (DOF). Pulmonary arterial pressure (PAP) was measured approximately every 3 months by a qualified veterinarian. Cattle were harvested at a commercial harvesting facility where carcass data and muscle samples were collected. In study two, weaned sim-angus steers (n = 41) were selected on heart failure risk categories using the same methodology outline above. Twenty steers were administered a steroidal growth promoting implant upon receiving (IMP) and twenty were untreated (NAT). Steers were fed to an average of 610 kg and data were collected using the same methodology outlined above. Data were analyzed using ANOVA, linear model, and Pearson correlation functions in R statistical software where PAP was used as a fixed continuous variable. Data were analyzed by study with the exception of live growth performance regression and correlations where data were combined. Linear regression within the combined datasets showed that initial mean PAP (P < 0.001), diastolic pressure (P < 0.001), and sex (P < 0.001) positively influenced ADG throughout the duration of the finishing period. Furthermore, initial PAP was moderately correlated with ADG (R = 0.38, P < 0.001). Gain to feed (G:F) was positively correlated with initial diastolic PAP (R = 0.31, P < 0.006). Neither initial mean PAP nor diastolic pressures impacted dry matter intake (DMI; P > 0.90), but sex was associated with DMI where steers had significantly decreased DMI (P = 0.003). Within study two, longissimus muscle objective color values were influenced by PAP where a* (redness; P < 0.001) and b* (yellowness; P < 0.04) values were negatively correlated with final PAP. These data begin to demonstrate the close relationship between live growth performance and pulmonary hypertension. More research is needed to better understand how cellular energy metabolism is potentially contributing to increased growth performance but negatively influencing muscle health in the form of oxygen binding capacity and inflammation. [ABSTRACT FROM AUTHOR]

Subclinical mastitis, a common intramammary disease in sheep production, can be costly to producers due to compromised performance and decreased longevity. Our research focused on preventative and therapeutic measures on mammary health where the objectives were to identify (1) the impact of Zn supplementation on the milk microbiome and (2) the impact of management practices at lambing and weaning on prevalence and cure rate of subclinical mastitis, the milk microbiome, and levels of antimicrobial resistance in milk bacteria. In study 1, the milk microbiome was characterized during the first 3 wk of lactation and at weaning in ewes divergent in dietary Zn supplementation (1× = CON or 3× recommendations = ZnTRT). Mammary health was assessed using somatic cell count (SCC) class. Amplicon sequencing revealed the presence of Staphylococcus, Mannheimia, Corynebacterium, and Pseudomonas, all major mastitis pathogens. Effects of breed, dietary Zn concentration, and SCC class on diversity were limited to early lactation, where CON milk had greater composition stability than ZnTRT milk (P = 0.02). In study 2, milk bacteria were characterized by culture; Staphylococcus spp. and Streptococcus spp. were tested for antimicrobial susceptibility. Subclinical mastitis prevalence ranged from 22–66% where coagulase-negative staphylococci (CoNS; 59%), bacilli (35%), Mannheimia haemolytica (10%), S. aureus (8%), streptococci (5%), and Corynebacterium spp. (5%) were common. Milk samples were compared by jug bedding treatment: jugs were cleaned and dried with barn lime before adding fresh straw (CLEAN) or fresh straw was added atop soiled bedding (SOILED). Bedding had no effect on subclinical mastitis (P = 0.57), but CoNS had greater sulfadimethoxine resistance in SOILED isolates (P = 0.03). Additional mastitis control methods at weaning were evaluated: penicillin injection (PENN), restricted feed access (FAST), or their combination (COMBO). Weaning treatment did not affect cure rate from weaning to 3-d post- weaning (P = 0.21). Further characterization of these samples via microbial sequencing are underway with source tracking analyses to investigate an exogenous route via retrograde transfer and environmental bacteria or endogenous route via an entero-mammary pathway. Results support that breed, animal husbandry, and mammary health variably affect the milk microbiome and provide novel insight to the impact of management practices in a milk microbiome longitudinal study. [ABSTRACT FROM AUTHOR]

Tremendous economic loss is attributed to high altitude disease mortality of calves in the Mountain West and Great Plains region. Additional economic losses may be associated with changes in feed efficiency and carcass quality in animals at higher risk of heart failure during the finishing phase. Thus, the objective of the current study is to evaluate economically relevant traits throughout the finishing period to determine inefficiencies associated with variable levels of heart failure risk and reproductive tract type of beef heifers. Both intact reproductive tract (n = 19) and ovariectomized (n = 18) heifers were stratified by risk category, where initial pulmonary arterial pressure (PAP) levels at or below 42 mmHg were designated as low risk and those above 42 mmHg as moderate/high risk. Heifers were fed a grain-based diet for 125 d before transportation to the harvest facility on d 126. All heifers were weighed in 2 wk intervals. Heifers were PAP tested by a qualified veterinarian in approximately 3 mo intervals during the feeding period. Feed intake data was collected for the last 55 d prior to harvest using the Vytelle SENSETM bunk system. Time of harvest was determined based on live weight and final ultrasound 12th rib fat thickness. Data were analyzed using the ANOVA function of R with tract type and risk as fixed effects. Comparisons were tested using a significance level of α = 0.05 and 0.05 (P ≤ 0.10) were considered tendencies. There were no interactions of risk category and tract type on performance or carcass characteristics (P ≥ 0.14). There was a tendency for higher total intake (P = 0.07) and relative growth rate (P = 0.04) among moderate/high risk heifers compared to the low-risk category. Hot carcass weight, marbling score, ribeye area, and USDA yield grade were not impacted (P ≥ 0.16) by risk category. Intact heifers had greater (P = 0.02) total gain than their ovariectomized contemporaries. However, marbling scores were higher (P = 0.04) among ovariectomized heifers compared to those from intact heifers. These data suggest that risk category and tract type minimally influence performance and carcass characteristics in a population that selects sires with low PAP scores. It remains unclear if more initial divergence in PAP scores would elicit greater impacts on performance and carcass characteristics in feedlot heifers. [ABSTRACT FROM AUTHOR]