Nikole E. Ineck

Forty castrated Holstein calves underwent an adrenocorticotropic hormone (ACTH) challenge to assess the effects of premortem stress on the longissimus lumborum (LL) following harvest. LL biopsies were collected before the challenge, at different harvest times (2, 12, 24, and 48 h; n = 10), and after 14 d aging. The expression of small heat shock proteins (SHSPs), deglycase 1 (DJ-1), and troponin were analyzed. Blood was analyzed throughout the ACTH challenge and at harvest for cortisol, oxidative stress, and complete blood count (CBC). Color and myofibrillar fragmentation index (MFI) were measured in aged samples. Unexpectedly, calves from different harvest times differed (p = 0.05) in cortisol response. Calves were divided into two different cortisol response groups (high or low; n = 20). Statistical analysis assessed the effects of cortisol response (n = 20), harvest time (n = 10), and their interaction. Harvest time altered SHSPs (p = 0.03), DJ-1 (p = 0.002), and troponin (p = 0.02) expression. Harvest time and cortisol response impacted steak color (p < 0.05), and harvest time altered steak pH (p < 0.0001). Additionally, various CBCs were changed (p < 0.05) by harvest time. Harvest time changed (p = 0.02) MFI. These data demonstrate that the protein expression, color, and MFI of the LL may be influenced by premortem stress.

The ocular surface microbiome is altered in certain disease states. The aim of this study was to characterize the bovine bacterial ocular surface microbiome (BBOSM) in the context of ocular squamous cell carcinoma (OSCC). The conjunctiva of normal (n = 28) and OSCC (n = 10) eyes of cows aged 2 to 13 years from two farms in Louisiana and Wyoming were sampled using individual sterile swabs. DNA extraction followed by 16S ribosomal ribonucleic acid (rRNA) gene sequencing and real-time polymerase chain reaction (RT-PCR) were performed to, respectively, assess the relative and absolute BBOSM. Discriminant analysis (DA) was performed using RT-PCR data, and relative abundance analysis was performed using 16S rRNA gene sequencing data. The 11 most abundant phyla in both normal and OSCC-affected cows were identified using 16S rRNA gene sequencing analysis. The relative abundance of Euryarchaeota was found to be significantly lower (p = 0.0372) in OSCC eyes compared to normal eyes. Relative abundance differences within and between geographic locations were also identified. Quadratic DA categorized samples as OSCC or normal with 100% sensitivity and 83.3–100% specificity. Relative abundance analysis identified relative BBOSM phylum alterations in OSCC. Quadratic DA can be used to accurately categorize BBOSM from normal and OSCC ocular surface samples.

Research suggests that androgens increase skeletal muscle growth by modulating polyamine biosynthesis. As such, the objective of this study was to investigate effects of anabolic hormones, polyamine precursors, and polyamines relative to proliferation, protein synthesis, and the abundance of mRNA involved in polyamine biosynthesis, proliferation, and protein synthesis in C2C12 and Sol8 cells. Cultures were treated with anabolic hormones (trenbolone acetate and/or estradiol), polyamine precursors (methionine or ornithine), or polyamines (putrescine, spermidine, or spermine). Messenger RNA was isolated 0.5 or 1, 12, or 24 h post-treatment. The cell type had no effect (p > 0.10) on proliferation, protein synthesis, or mRNA abundance at any time point. Each treatment increased (p < 0.01) proliferation, and anabolic hormones increased (p = 0.04) protein synthesis. Polyamines increased (p < 0.05) the abundance of mRNA involved in polyamine biosynthesis, proliferation, and protein synthesis. Treatment with polyamine precursors decreased (p < 0.05) the abundance of mRNA involved in proliferation and protein synthesis. Overall, C2C12 and Sol8 myoblasts do not differ (p > 0.10) in proliferation, protein synthesis, or mRNA abundance at the time points assessed. Furthermore, anabolic hormones, polyamines, and polyamine precursors increase proliferation and protein synthesis, and polyamines and their precursors alter the abundance of mRNA involved in growth.

This research analyzed how maternal plane of nutrition during mid-gestation impacts growth, blood metabolites, expression of microRNA and messenger RNA in skeletal muscle, feedlot performance, and carcass characteristics of progeny. Thirty-two cows were bred to the same Angus sire and fed to either maintain a body condition score (BCS) of 5.0 to 5.5 (maintenance [MAIN]; n = 15) or to lose 1 BCS (restriction [REST]; n = 17) over an 84-d period of mid-gestation. Following the second trimester, all cows were co-mingled and fed at maintenance for the remainder of gestation. Following the 84-d treatment period, REST cows had a lower (P < 0.01) BCS than MAIN cows. At the end of the third trimester, there was no difference (P = 0.78) in BCS between the treatment groups. There was no difference (P > 0.10) between offspring in birthweight, weaning weight, average daily gain, feed efficiency, dry matter intake, carcass yield, steak quality, or in circulating levels of glucose, cortisol, insulin, or insulin-like growth factor-1. REST offspring expressed more (P < 0.05) miR-133a, miR-133b, miR-181d, miR-214, miR-424 and miR-486 at weaning than MAIN offspring. At harvest, REST offspring expressed more (P < 0.05) miR-133a and less (P < 0.01) miR-486 than MAIN offspring. REST steaks were perceived as more tender (P = 0.05) by a trained sensory panel. These results indicate that maternal nutrient restriction during mid-gestation resulting in a loss of 1 BCS has an effect on microRNA expression in the skeletal muscle but does not alter postnatal growth potential, carcass quality, or end product quality of the offspring. This suggests that moderate restriction in maternal nutrition during the second trimester, which results in a drop in BCS that can be recovered during the third trimester, should not cause alarm for producers when considering future offspring performance.