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, 3.5 g/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. 31 kg), weaning (197 vs. 214 kg), and 445 d of age (398 vs. 429 kg) (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.

In tropical conditions, beef cows on pasture often experience protein restriction during mid-to-late gestation, potentially impacting offspring development negatively. To address this, we investigated the effects of strategic protein supplementation for pregnant beef cows fed low-quality forage during mid-gestation on the postnatal growth trajectory of their offspring. The supplementation program, implemented during mid-gestation, increased dry matter intake by addressing nitrogen deficiency in the rumen, resulting in meeting 98% and 92% of protein and energy requirements in supplemented cows. In contrast, nonsupplemented cows met only 30% and 50% of these requirements, respectively. Consequently, protein supplementation positively influenced the postnatal growth trajectory of the offspring, attributed to beneficial changes in secondary myogenesis and hypertrophy processes. Supplementing cows with crude protein also stimulated lipogenesis, potentially contributing to intramuscular fat deposition, particularly in females. Therefore, this study emphasizes the importance of nutritional interventions for pregnant beef cows fed low-quality forage.

Ruminal responses, digestibility, and blood parameters of beef cattle fed diets without forage with different hybrids and processing of the corn.

The objective of this study was to evaluate the effects of corn hybrid and processing methods on intake and digestibility of nutrients, rumen fermentation and blood metabolites of steers fed no-forage finishing diets. Four ruminally fistulated Nellore castrated steers (502 ± 15 kg initial body weight) were distributed in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement consisting of two corn hybrids (semi-dent and flint) and two processing methods (dry milled and high moisture grain). Interactions of hybrid and processing methods were observed on intake of dry matter (DM), organic matter (OM) and crude protein (CP), as well as on digestibility of DM and CP, rumen pH and ammonia nitrogen (N-NH3 ). There was no interaction between hybrid and processing for the volatile fatty acids (VFA) total, acetate (C2), propionate (C3), isobutyric (iC4) and valeric (nC5) concentrations. VFA total concentration shown an average of 103.4 mmol/L. The C2 and C3 concentrations had no effect of the hybrid or processing with averages of 58.7 mmol/L for C2, and 31.3 mmol/l for C3. There was an effect of the processing method on starch consumption and fecal pH, the highest values were observed in grains with high moisture content. Starch digestibility was 0.89 g/g in dry milled and 0.96 g/g in high moisture corn. The greatest digestibility of starch in high moisture corn, irrespective of the corn hybrid, provided evidence of an increase in the energy supply, which may improve the feed efficiency and growth performance of cattle fed no-roughage finishing diets.

Proteomic analysis reveals changes in energy metabolism of skeletal muscle in beef cattle supplemented with vitamin A.

BACKGROUND: Vitamin A has been reported as a factor influencing marbling deposition in meat from animals. Although the mechanisms by which vitamin A regulates lipid metabolism in mature adipocytes are already well-established, information regarding molecular mechanisms underlying the effects of vitamin A on the regulation of intramuscular fat deposition in beef cattle still remains limited. The present study aimed to assess the molecular mechanisms involved in the intramuscular fat deposition in beef cattle supplemented with vitamin A during the fattening phase using a proteomic approach. RESULTS: Vitamin A supplementation during the fattening phase decreased intramuscular fat deposition in beef cattle. Proteome and phospho-proteome analysis together with biological and networking analysis of the protein differentially abundant between treatments indicated that Vitamin A supplementation affects the overall energy metabolism of skeletal muscle, impairing lipid biosynthesis in skeletal muscle. CONCLUSION: Vitamin A supplementation at fattening phase impairs intramuscular fat deposition in beef cattle likely by changing the energy metabolism of skeletal muscle. The interaction of retinoic acid and heat shock 70-kDa protein may play a pivotal role in intramuscular fat deposition as a consequence of vitamin A supplementation by impairing de novo fatty acid synthesis as a result of a possible decrease in insulin sensitivity in the skeletal muscle. © 2020 Society of Chemical Industry.

Effect of post-weaning growth rate on carcass traits and meat quality of Nellore cattle.

This study evaluated the effects of growth rate during post-weaning growing phase on carcass traits and beef quality. Thirty-four Nellore young bulls were randomly assigned to one of three treatments: LOW, MEDIUM or HIGH growth rate during post-weaning growing phase followed by high growth rate in the finishing phase. The growth rate affected (P<0.05) all carcass traits evaluated at the end of post-weaning growing phase, except ultimate pH. Carcass dressing was greatest (P<0.05) for the HIGH growth rate group in both phases. Beef from the HIGH group exhibited the greatest (P<0.05) sarcomere length and a* and b* colour values at the end of post-weaning growing phase. However, post-weaning growth rate did not affected (P>0.05) collagen content and solubility, myofibrillar fragmentation index and Warner-Bratzler shear force. Our data suggest that a low post-weaning growth rate produces lighter and leaner carcasses, but it does not affect meat quality traits in Nellore young bulls.

Evaluation of carcass traits and meat characteristics of Guzerat-crossbred bulls.

Our objective was to evaluate carcass and meat characteristics of Guzerat-crossbred bulls finished in feedlot. Carcasses from 18 bulls, randomly selected from a larger group of 36 bulls, consisting of F1 Guzerat×Holstein ("Guzholstein"); F1 Guzerat×Nellore ("Guzonell"); and 1/2 Simmental+1/4 Guzerat+1/4 Nellore (Three-Cross; n=6 each group) were used. Cold carcass weight was greater (P=0.01) for Three-Cross compared with "Guzonell" and "Guzholstein". Three-Cross carcasses had greater (P<0.01) rib-eye-area and 100-kg-adjusted rib-eye-area among groups. Longissimus lumborum length did not differ (P>0.05) among groups, but depth was greater (P<0.01) for Three-Cross compared with other groups. "Guzholtein" had lesser (P=0.05) shear force compared with "Guzonell", with Three-Cross being intermediate. We conclude that "Guzholstein" is an adequate option for producers willing to finish this kind of genetic group, as it is comparable or better than Bos indicus crosses and B. indicus×Bos taurus bulls.

Postmortem proteolysis in three muscles from growing and mature beef cattle.

The objective of this study was to determine calpain system activity and postmortem protein degradation in three muscles from growing (n=6, 7.3 ± 0.5 months) and mature (n=6, 106.7 ± 43.1 months) beef cattle. The ratio of µ-calpain:total calpastatin activity tended to be lower in mature animals (P=0.08), suggesting reduced potential for proteolysis. Additionally, muscles from the mature group had greater calpastatin activity compared to calves at 6 days postmortem and had less µ-calpain autolysis and troponin-T and titin degradation during the aging period (P<0.01). Between the longissimus, semimembranosus, and triceps brachii muscles, the triceps brachii had the least postmortem proteolysis, with greater calpastatin activity and less troponin-T and titin degradation compared to other muscles (P<0.01). These data suggest that calpastatin activity in muscle from older animals is more persistent postmortem. This difference may contribute to the decreased protein degradation and increased toughness of beef from mature cattle, even after aging.

Like pigs, and unlike other breeds of cattle examined, mature Angus-derived adipocytes may extrude lipid prior to proliferation in vitro.

A large number of studies have shown that mature adipocytes are able to dedifferentiate in vitro into progeny cells, which possess proliferative capacity and mutilineage potential. Our present study confirms that mature adipocytes derived from Angus cattle also dedifferentiate into proliferative-competent progeny cells. However, this report is unlike any published for all other breeds of cattle we have worked with or that we have seen in published reports, in which mature adipocytes retain and distribute lipids into daughter cells symmetrically or asymmetrically. In the present work, we noted that Angus-derived mature adipocytes extruded a majority of their cellular lipid droplets prior to cell division. In this manner, these cells are processing lipid in a manner observed in mature adipocytes isolated from swine tissue. These results suggest that regulation of the mechanism(s) underlying lipid processing might be different between and within animal breeds. Lipid processing in beef-derived adipocytes during dedifferentiation may serve as a unique animal model for studying lipid metabolism during reverse adipogenesis.