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Early puberty is associated with improved long-term reproductive performance. Predicting who will achieve early puberty is limited to intensive, invasive serial blood collections for measurement of reproductive hormones. The vaginal genome during pubertal development has potential as biomarkers of early estrus in the pre-pubertal period. Pre-pubertal gilts (n =13) were followed from d74 ± 3 of age until first estrus or d214 ± 1 of age. Blood, vaginal epithelia, and anogenital distance were collected at five timepoints during reproductive development (d74, d104, d130, d160 and first estrus or end of trial). Total RNA was isolated from vaginal epithelia and relative gene expression of two toll-like receptors (TLR-4 and TLR-5), tacykinin precursor-3 (TAC-3), insulin-like growth factor-1 (IGF-1), and estrogen receptor (ERα)-alpha was quantified by real time RT-PCR, relative to expression of RPLP0. Four gilts exhibited estrus early (< d184), 3 were average (d194 to 195), 3 were late (d203 to 213), and 3 were deemed anestrus. Comparison of expression of each gene relative to d70 was performed using the PCR package in RStudio (version 1.2.5025) and Fisher's exact t-test for TLR-4, TLR-5 and TAC-3, and ANOVA for ER-alpha and IGF-1. Correlation analysis examined the relationship between anogenital distance and age at first estrus. A single blood draw for serum progesterone was obtained 8 days after recorded first estrus or end of trial; the presence of serum progesterone supports the visual identification of standing estrus. Expression of IGF-1 and TAC-3 were up-regulated 9- and 7-fold, respectively at d160 ( P < 0.05). Expression of ERα tended to be upregulated 3-fold at d104 ( P = 0.08) and expression of TLR-4 and TLR-5 was not detected until first estrus. Anogenital distance was positively correlated to the first estrus. These transcripts associated with reproduction warrant further investigation into use as biomarkers to detect early estrus., Competing Interests: Conflicts of interest: The authors have no conflict of interest to disclose.

The objective of this study was to evaluate differences in the performance of offspring of boars selected with an index emphasizing resilience and boars selected based on a traditional index, emphasizing feed efficiency and carcass quality (traditional) index vs. a customized (resilience) index. The resilience index was identical to the traditional index, except that extra emphasis was placed on piglet vitality (increased by 66%), growth rate (decreased by 14%), and feed intake (increased substantially by 5,157%). Sows were mated to either boars selected based on the resilience index or boars selected on the traditional index. Weaned offspring were vaccinated for Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and experimentally infected with PRRSV RFLP 1-7-4 four weeks later. Offspring were allocated to pens ( n ~ 27 pigs/pen; n  = 27 pens/group) by sire-selection group for a total of 1,458 pigs in 54 pens. The weight of each pen was recorded on 0, 42, and 110 d postinfection (DPI) and used to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). Mortalities were recorded from 0 to 110 DPI and necropsies were routinely performed to characterize pathogens present within the barn. Pigs classified as full value (i.e., >104 kg and void of defects) were slaughtered and hot carcass weight (HCW), backfat, loin depth, and lean weight were obtained from the slaughter plant. Effects of progeny group on performance, carcass characteristics, and mortality rate were estimated with a mixed linear model. Differences between progeny groups in ADG ( P  > 0.27), HCW ( P  = 0.68), backfat ( P  = 0.13), or loin depth ( P  = 0.39), and mortality rate ( P  = 0.29) were not detected. From 0 to 42 DPI, offspring of boars selected based on the resilience index had higher ADFI (0.06 kg/d, P  = 0.01) and higher FCR (0.12, P  = 0.01). In summary, results from this study do not support selection of boars for increased feed intake, piglet viability, and robustness in order to prevent losses caused by PRRSV, but selection response was only measured after one generation of male selection. The impact of multiple generations of selection, or the development of an index including traits derived from data collected under disease-challenged conditions should be explored. The data collected for this study are a valuable resource to explore additional genetic selection strategies for enhanced resilience to a multifactorial PRRS challenge., Competing Interests: E.A.L., D.H., and S.D. are employed by Pipestone Applied Research or were at the time of project completion, a company with a vested interest in conducting research trials. J.D and J.M.E.E. are employed by Topigs Norsvin USA, a company that markets breeding stock to the commercial swine industry., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The Afrikaner breed of cattle is indigenous to South Africa and, due to their hardiness, was once the most popular breed amongst South African farmers, although in recent years their numbers have decreased. The goal of this study was to assess factors affecting length of productive life, defined as the interval between production of the first and last calf, in Afrikaner cattle using survival analysis. The data spanned 40 years with an observed measure of length of life for 29,379 cows from 374 herds. Relative to similar analyses, few (n = 2964; 8.4%) cows had records that were right censored. The median length of productive life of an Afrikaner cow was just less than 6 years. Cows that were younger at their first parturition had longer productive lives than those that were older at their first calving. Cows that were born in the period from December to February had shorter productive lives than those born between March and November. The estimated animal genetic variance of 0.266 resulted in a heritability estimate for length of productive life in Afrikaner cattle of 0.225. Thus, there appeared to be sufficient additive genetic variance in Afrikaner cattle to enable genetic improvement in their length of productive life., (© 2024 The Authors. Journal of Animal Breeding and Genetics published by John Wiley & Sons Ltd.)

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 CuSO 4 ) and 15 mg of Zn (as ZnSO 4 ) 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.

The objective of this study was to compare the influence of beef production systems using additive combinations of growth-promotant technologies on meat quality. Steer calves ( n  = 120) were assigned to 1 of 4 treatments: 1) no technology (NT; control), 2) antibiotic treated (ANT; NT plus therapeutic antibiotics, monensin, and tylosin), 3) implant treated (IMP; ANT plus a series of three implants), and 4) beta-agonist treated (BA; IMP plus ractopamine-HCl). Muscle biopsy samples from the longissimus lumborum were extracted from a subset ( n  = 4 per treatment) of steers to evaluate expression of calpain-1, calpain-2, and calpastatin using real-time RT-PCR. Following carcass chilling, objective color ( L *, a *, and b *) was evaluated. The right strip loin was removed from each carcass, portioned into 2.54-cm steaks, and designated to 7, 14, or 21 d postmortem aging periods for analysis of cook loss and Warner-Bratzler shear force ( WBSF ). The anterior face of each strip loin was used for analysis of crude fat and moisture. Treatment influenced ( P  < 0.001) L *, a *, and b *. The NT and IMP treatments had greater ( P  < 0.01) L * values, ANT was intermediate, and BA had the lowest ( P  < 0.01) L * values. The NT and IMP treatments had higher ( P  < 0.01) a * and b * values compared with ANT, which were higher ( P  < 0.01) than BA. Steaks from implanted steers (IMP and BA) tended ( P ≤ 0.067) to exhibit higher a * and b * than steaks from nonimplanted steers. Cattle in the NT and ANT treatments produced steaks with increased ( P  < 0.01) crude fat percentage compared with the IMP and BA treatments, which were similar ( P  > 0.05). Percent moisture of NT steaks was lower ( P  < 0.01) than all other treatments, ANT was intermediate, and IMP and BA were similar ( P  > 0.05) and had the highest ( P  < 0.01) moisture content. Cook loss tended to be greater ( P  = 0.088) for implanted steers (IMP and BA) compared to nonimplanted steers (NT and ANT). Steaks from NT and ANT treatments were more tender ( P  < 0.05) than IMP and BA, which were similar ( P  > 0.05). Thus, WBSF was lower ( P  < 0.001) in nonimplanted than implanted steaks. Expression of calpastatin was increased ( P ≤ 0.025) in ANT and BA treatments, and there was a tendency for expression of calpain-2 to be increased ( P  = 0.081) in ANT compared to NT. These results suggest that production systems with limited use of growth promoting technology produced strip loins with more crude fat, less moisture and cook loss, and improved tenderness., Competing Interests: The authors declare no real or perceived conflict of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science.)

This study investigated the impacts of metabolizable protein (MP) restriction in primiparous heifers during mid- and/or late-gestation on progeny performance and carcass characteristics. Heifers were allocated to 12 pens in a randomized complete block design. The factorial treatment structure included two stages of gestation (mid- and late-) and two levels of dietary protein (control (CON); ~101% of MP requirements and restricted (RES); ~80% of MP requirements). Half of the pens on each treatment were randomly reassigned to the other treatment at the end of mid-gestation. Progeny were finished in a GrowSafe feeding system and carcass measurements were collected. Gestation treatment x time interactions indicated that MP restriction negatively influenced heifer body weight (BW), body condition score, and longissimus muscle (LM) area (p < 0.05), but not fat thickness (p > 0.05). Treatment did not affect the feeding period, initial or final BW, dry matter intake, or average daily gain of progeny (p > 0.05). The progeny of dams on the RES treatment in late gestation had a greater LM area (p = 0.04), but not when adjusted on a hot carcass weight basis (p > 0.10). Minimal differences in the animal performance and carcass characteristics suggest that the level of MP restriction imposed during mid- and late-gestation in this study did not have a significant developmental programming effect.