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.

Heat stress promotes adaptive physiological responses and alters mrna expression of ruminal epithelium markers in Bos taurus indicus cattle fed low- or high-energy diets.

This research aimed to evaluate the impact of temperature and energy status on the thermal indices, physiological parameters, and ruminal papilla mRNA expression levels of Zebu beef heifers (Bos taurus indicus). In this trial, we used six ruminal-cannulated Nellore females. The experimental design was a 6 × 6 Latin square, with six treatments and six periods. The research used a 2 × 2 + 2 factorial scheme. The arrangement comprised: two thermal conditions [thermoneutrality (TN; 21.6 °C) or heat stress (HS, 34 °C)]; two dietary energy levels (low or high-energy); and two additional treatments, with heifers exposed to the TN, but pair-fed with females exposed to HS (PFTN). For our purposes, body temperature, heart and respiratory rates were measured and the relative mRNA expression was quantified using the PCR-RT technique. Compared to TN or PFTN, the HS increased the body temperature measurements in the morning and evening (p ≤ 0.04). Heart rate was 22% greater for heifers under HS than for TN (p < 0.01) and 13% higher for those under HS than PFTN (p = 0.03) in the morning. Respiratory rates increased with HS exposure compared to TN or PFTN (p < 0.01). Heifers submitted to HS and fed low-energy diets had and tended to have lower caspase 3 (CASP3, p 0.001) and sodium-glucose cotransporter type 1 (SGLT1; p = 0.17) mRNA expressions, respectively. Heat-stressed heifers fed low-energy diets also increased the putative anion transporter (PAT1; p ≤ 0.01) mRNA expressions by 60%. Heifers under HS-fed high-energy diets had greater kallikrein-related peptidase (KLK) 9 expressions (p = 0.02), while KLK10 (p = 0.11) tended to be up-regulated in heifers in TN-fed a low-energy diets. In conclusion, heat stress down-regulated the mRNA expression of rumen markers related to short-chain fatty acids transport and pH modulation.

Use of Castor Bean Meal, Biodiesel Industry Coproduct, in A Lamb Production System Using Creep-Feeding in Brazil.

This study aimed to evaluate the replacement of soybean meal by detoxified castor bean meal on the intake and digestibility of nutrients, body weight gain, carcass yield, physiological and urinary parameters, and creep-feeding method effectiveness. For this trial, 43 male lambs were used, Dorper × Santa Inês, with an average initial body weight of 7.95 kg, 15 days old. Lambs were distributed in a randomized block design. Five experimental diets were provided: Without supplementation, with supplementation but without the use of castor bean meal, and with gradual levels of replacement of soybean meal by detoxified castor bean meal (33%, 67%, and 100%). Higher values of DMI and nutrient digestibility (p < 0.05) were observed for animals that received supplements. The milk intake did not differ among the diets. The DMD showed a linear effect, while NDFD had a quadratic effect, depending on castor bean meal inclusion. The carcass yield did not differ between experimental diets. There was no significant effect on the urinary volume and metabolites investigated. In conclusion, the replacement of soybean meal by detoxified castor bean meal does not compromise animals' development. Besides, the creep-feeding method positively affects lamb development, with higher body weight gain for supplemented animals.

Total nutrient digestibility and small intestine starch digestion in Nellore and Angus young bulls fed a whole shelled corn diet.

Eighteen Nellore and 18 Angus young bulls with BW of 381 ± 12 kg were randomly assigned into two feeding groups (whole shelled corn [WSC] or ground corn with silage [GC]) to evaluate the interaction of breed and diet on total nutrient digestibility, pancreatic α-amylase, and maltase activity and SLC5A1expression in the small intestine. Experimental diets (DM basis) included (a) a diet containing 30% corn silage and 70% GC and soya bean meal-based concentrate and (b) a diet containing 85% WSC and 15% of a soya bean meal- and mineral-based pelleted supplement. The treatments were Nellore fed GC diet; Nellore fed WSC diet; Angus fed GC diet; and Angus fed WSC diet. Total faecal collection for the digestibility trial occurred from day 48 until day 50 of the experimental period. Feeding the WSC diet reduced DM and NDF intake (p < 0.01). Angus had greater DM and nutrient intake in kg/day (p < 0.01). However, there was no breed effect on DM and nutrient intakes based on percentage of BW (p > 0.19). Angus had greater starch digestibility (p = 0.03) than Nellore. Cattle fed the WSC diet had greater DM, NDF and starch digestibility (p < 0.01) compared with those fed the GC diet. The activity of pancreatic α-amylase (U/g of protein) was greater in Nellore (p < 0.01) and was not affected by diet (p = 0.52). In duodenum, maltase activity (U/g of protein) was greater in bulls fed GC diet (p = 0.02). Expression of the gene SLC5A1was not affected by breed or diet (p > 0.05). In conclusion, Nellore had less capacity to digest starch. However, they did not have less pancreatic α-amylase and duodenal maltase activity compared to Angus. The use of the WSC diet increases DM and total nutrient digestibility.

Nutrigenomics and Beef Quality: A Review about Lipogenesis.

The objective of the present review is to discuss the results of published studies that show how nutrition affects the expression of genes involved in lipid metabolism and how diet manipulation might change marbling and composition of fat in beef. Several key points in the synthesis of fat in cattle take place at the molecular level, and the association of nutritional factors with the modulation of this metabolism is one of the recent targets of nutrigenomic research. Within this context, special attention has been paid to the study of nuclear receptors associated with fatty acid metabolism. Among the transcription factors involved in lipid metabolism, the peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding proteins (SREBPs) stand out. The mRNA synthesis of these transcription factors is regulated by nutrients, and their metabolic action might be potentiated by diet components and change lipogenesis in muscle. Among the options for dietary manipulation with the objective to modulate lipogenesis, the use of different sources of polyunsaturated fatty acids, starch concentrations, forage ratios and vitamins stand out. Therefore, special care must be exercised in feedlot feed management, mainly when the goal is to produce high marbling beef.

Achieving body weight adjustments for feeding status and pregnant or non-pregnant condition in beef cows.

BACKGROUND: Beef cows herd accounts for 70% of the total energy used in the beef production system. However, there are still limited studies regarding improvement of production efficiency in this category, mainly in developing countries and in tropical areas. One of the limiting factors is the difficulty to obtain reliable estimates of weight variation in mature cows. This occurs due to the interaction of weight of maternal tissues with specific physiological stages such as pregnancy. Moreover, variation in gastrointestinal contents due to feeding status in ruminant animals is a major source of error in body weight measurements. OBJECTIVES: Develop approaches to estimate the individual proportion of weight from maternal tissues and from gestation in pregnant cows, adjusting for feeding status and stage of gestation. METHODS AND FINDINGS: Dataset of 49 multiparous non-lactating Nellore cows (32 pregnant and 17 non-pregnant) were used. To establish the relationships between the body weight, depending on the feeding status of pregnant and non-pregnant cows as a function of days of pregnancy, a set of general equations was tested, based on theoretical suppositions. We proposed the concept of pregnant compound (PREG), which represents the weight that is genuinely related to pregnancy. The PREG includes the gravid uterus minus the non-pregnant uterus plus the accretion in udder related to pregnancy. There was no accretion in udder weight up to 238 days of pregnancy. By subtracting the PREG from live weight of a pregnant cow, we obtained estimates of the weight of only maternal tissues in pregnant cows. Non-linear functions were adjusted to estimate the relationship between fasted, non-fasted and empty body weight, for pregnant and non-pregnant cows. CONCLUSIONS: Our results allow for estimating the actual live weight of pregnant cows and their body constituents, and subsequent comparison as a function of days of gestation and feeding status.