The appropriate supply of nutrients in pregnant cows has been associated with the optimal development of foetal tissues, performance of their progeny and their meat quality. The aim of this study was to evaluate supplementation effects of grazing cows in different stages of gestation on skeletal muscle development and performance of the progeny. Thereby, 27 Nellore cows were divided into three groups (n=9 for each group) and their progeny as follows: UNS, unsupplemented during gestation; MID, supplemented from 30 to 180 days of gestation; LATE, supplemented from 181 to 281 days of gestation. The percentage composition of the supplement provided for the matrices was the following: ground corn (26.25%), wheat bran (26.25%) and soya bean meal (47.5%). The supplement was formulated to contain 30% CP. Supplemented matrices received 150 kg of supplement (1 and 1.5 kg/day for cows in the MID and LATE groups, respectively). After birth, a biopsy was performed to obtain samples of skeletal muscle tissue from calves to determine number and size of muscle fibres and for messenger RNA (mRNA) expression analysis. The percentage composition of the supplement provided for the progeny was the following: ground corn grain (30%), wheat bran (30%), soya bean meal (35%) and molasses (5%). The supplement was formulated to contain 25% CP and offered in an amount of 6 g/kg BW. Performance of the progeny was monitored throughout the suckling period. Means were submitted to ANOVA and regression, and UNS, MID and LATE periods of supplementation were compared. Differences were considered at P0.10). Similarly, no differences were observed between calves for nutrient intake (P>0.10). However, greater subcutaneous fat thickness (P=0.006) was observed in the calves of LATE group. The ribeye area (P=0.077) was greater in calves born from supplemented compared with UNS cows. The supplementation of pregnant cows did not affect the muscle fibre size of their progeny (P=0.208). On the other hand, calves born from dams supplemented at mid-gestation had greater muscle fibre number (P=0.093) compared with calves from UNS group. Greater mRNA expression of peroxysome proliferator-activated receptor α (P=0.073) and fibroblast growth factor 2 (P=0.003) was observed in the calves born from MID cows. Although strategic supplementation did not affect the BW of offspring, it did cause changes in carcass traits, number of myofibres, and mRNA expression of a muscle hypertrophy and lipid oxidation markers in skeletal muscle of the offspring.

The objective of the present study was to evaluate the effect of increasing levels of prepartum and postpartum protein supplementation on nutrient intake and digestibility, productive performance and metabolic status of beef heifers on tropical pasture. Twenty-eight pregnant beef heifers with bodyweight and body condition score of 459.7 ± 6.8 kg and 5.8 ± 0.10 respectively, were used. The experiment was performed according to a completely randomised design, with the following four treatments: 0.0, 0.4, 0.8 and 1.2 kg/animal.day of protein supplement containing 25% crude protein. All animals received a mineral mixture ad libitum. The experiment lasted 210 days, divided into three experimental periods. The supplementation level increased the intake of all evaluated nutrients, digestibility of organic matter, neutral detergent fibre corrected for ash and protein, as well as higher average daily gain prepartum and bodyweight of calves at birth (P < 0.05). Protein supplement at the levels evaluated did not affect body condition score (P > 0.05). An interaction effect between treatment × days in relation to calving occurred for concentrations of serum urea nitrogen, total proteins, albumin and globulins (P < 0.05). Supplementation did not affect glucose, triglyceride, non-esterified fatty acids, β-hydroxybutyrate or progesterone (P > 0.05). In conclusion, supply of up to 1.2 kg/day of protein supplement for grazing beef heifers optimises forage intake and average daily gain before calving, and improves the indicators of the protein status.

Beef cows' milk yield is typically determined by measuring milk yield once daily and then doubling this value to estimate daily production. However, it is not known whether this is accurate. Thus, we aimed to determine the association between morning and afternoon milk yield in grazing Nellore cows. Eighty Nellore cows were used, with initial weight of 516.0 ± 1.0 kg. The experiment was a completely randomized factorial scheme, with 20 replications and four treatments (i.e., + or - pre-partum supplementation in combination with + or - post-partum supplementation): PRMM-1 kg of supplement/cow/day for 90 days pre-partum; MMPS-1 kg of supplement/cow/day for 90 days post-partum; PRPS-1 kg of supplement/cow/day for 90 days pre-partum and 90 days post-partum; and MM-only mineral mix ad libitum during pre- and post-partum. Milk was sampled on days 45, 135, and 225 post-partum (early, middle, and late lactation, respectively). No effects were observed of pre- and post-partum supplementation on milk yield (P > 0.05). The afternoon/morning proportion of 0.45 in the early third of lactation was higher than other stages, which had a proportion of 0.41 (P < 0.05). Post-partum supplementation increased milk protein in the morning and afternoon milking (P < 0.05). There was also no effect of pre- and post-partum supplementation on afternoon-morning proportion other milk components (P> 0.05). We conclude that estimating daily milk production of grazing beef cattle by multiplying a once daily milking amount times two is not accurate. Under the conditions of this study, proportion of total daily production represented by the ratio of afternoon/morning milking was 0.45 in early lactation (first third) and 0.41 in mid- and late lactation.

The objective in this study was to evaluate the effects of supplementation levels on productive and nutritional performance and metabolic profile in suckling female calves under grazing. Forty female calves (averaging 3.5±0.06 months and 127.3±2.68 kg), and their respective dams were distributed in a completely randomized design with two treatments and twenty replicates. The treatments were 1) 4 g kg-1 body weight (BW) of supplement or 2) 6 g kg-1 BW of supplement. Forage and organic matter (OM) intake did not affect (P > 0.05) by levels of supplement, though crude protein and non-fibrous carbohydrates intake were greater (P < 0.05) by increasing supplementation level. There was no effect (P > 0.05) the supplementation levels on OM and CP digestibility. The metabolic profile of the animals was not affected (P > 0.05) by supplementation level. Average daily gain, longissimus dorsi area, fat thickness over rump of the animals did not affect (P > 0.05) by levels of supplement. However, there was trend of increasing (P=0.074) in fat thickness over loin by increase the supplementation level. Although the body growth of animals was similar (P > 0.05) between treatments, there was observed a trend of increase (P=0.064) in ratio BW:Height at the withers by increasing supplementation levels. In conclusion, increasing the supplementation level of 4 to 6 g kg-1 of BW, not improve the productive and nutritional performance and metabolic status in female calves under grazing on creep-feeding system.

The objective was to evaluate the effect of substituting soybean meal with cottonseed meal in supplements containing 15% and 30% of crude protein (CP), as well as evaluate the effect of supplementation use, on the performance and nutritional status of Nellore heifers. Forty heifers that were 13 months old and 250 ± 4 kg were kept in five 2.5-ha paddocks covered with Brachiaria decumbens. They were compared as they received different supplements (1 kg/head.day) in a 2 × 2 + 1 factorial – two protein sources (soybean and cottonseed meal) by two protein concentrations (15% and 30%) plus a Control treatment, which was a mineral mix only. The supplemented heifers showed greater weight gains, final bodyweight (P < 0.10) and higher intake of all evaluated nutrients (P < 0.10), as well as greater digestibility of these nutrients compared with those from the Control treatment. The animals fed supplements containing 15% CP had lower digestibility of dry matter, organic matter, CP and neutral detergent insoluble fibre corrected for ash and protein. These animals also had lower total digestible nutrients as compared with those which received a supplement containing 30% CP (P < 0.10). The treatments containing cottonseed meal provided greater dry matter digestibility (P < 0.10). Cottonseed meal can fully substitute soybean meal to grazing heifers during the rainy season. Supplements containing 30% of CP provided greater digestibility than 15% CP supplements. Supplemented animals had better performance.