Context: Few studies have evaluated the effects of providing concentrate pre- or postpartum, or during both of these intervals, to beef cows grazing tropical pastures, even though this information is important for planning breeder herd management.

Aims: A study was undertaken to examine the effects of supplementation with concentrates before calving (prepartum), after calving (postpartum) or during both these intervals on production and reproductive efficiency in Bos indicus beef cows grazing Urochloa decumbens pasture.

Methods: Nellore cows, initially 6 months pregnant (mean ± s.e.), weighing 516 ± 1.3 kg and body condition score 4.7 ± 0.15 (1–9 scale), were used in an experiment with four treatments in a 2 × 2 factorial design with 20 animals per treatment. The treatments comprised no supplementation or provision of a supplement (1 kg/cow.day containing 28% crude protein) for 90 days prepartum only, 90 days postpartum only or during the pre- and postpartum intervals.

Key results: Responses could be described in terms of the main effects of providing the supplement pre- or post-calving; the interactions were not significant (P > 0.05). Prepartum supplements increased the cow bodyweight at calving by 29 kg, and calf birthweight by 3.7 kg (P < 0.05). Supplementation increased (P < 0.05) the final bodyweight, average daily gain and final body condition score of the cows. Postpartum supplementation tended to increase milk yield (P = 0.065), and increased milk protein concentration (P < 0.05). Prepartum supplementation increased serum urea nitrogen, glucose and progesterone, and reduced non-esterified fatty acids (P < 0.05) and β-hydroxybutyrate concentrations (P < 0.05) during lactation. Postpartum supplementation, but not prepartum supplementation, increased the conception rate (P < 0.05).

Conclusion: In mature Nellore cows grazing Urochloa decumbens pasture, prepartum supplementation with 1 kg/cow.day of concentrate with body condition score >4 did not change the response to postpartum supplementation.

Implications: Prepartum supplementation may increase cow performance and calf weight at birth, whereas postpartum supplementation may improve the reproductive efficiency.

背景：很少有研究评估过在产前或产后或在这两个时间间隔内向热带牧场放牧的肉牛提供浓缩奶的效果，尽管此信息对于规划种猪群管理很重要。

目的：进行了一项研究，以研究在产犊前（产前），产犊后（产后）或在这两个时间间隔内补充浓缩物对放牧Urochloa decumbens牧场的印度s肉牛的生产和生殖效率的影响。

方法： Nellore牛最初怀孕6个月（平均±sec），体重516±1.3 kg，身体状况评分4.7±0.15（1–9量表），用于2×2因子设计的4种治疗方法，每种治疗20只动物。这些治疗包括仅在产前90天，仅在产后90天或在产前和产后间隔期间不补充或不提供补充剂（1 kg /牛/天，含有28％的粗蛋白）。

关键结果：应对措施可根据产前或产后补充营养品的主要作用来描述；交互作用不显着（P > 0.05）。产前补充品使犊牛体重增加29公斤，犊牛出生体重增加3.7公斤（P <0.05）。补充增加（P <0.05）母牛的最终体重，平均日增重和最终身体状况评分。产后补充往往会增加牛奶产量（P = 0.065），并增加牛奶蛋白浓度（P <0.05）。产前补充会增加血清尿素氮，葡萄糖和孕酮，减少非酯化脂肪酸（P<0.05）和哺乳期间的β-羟基丁酸酯浓度（P <0.05）。产后补充而不是产前补充增加了受孕率（P <0.05）。

结论：在放牧Urochloa decumbens牧场的成年内洛奶牛中，产前补充1 kg /牛的母牛。身体状况评分> 4的一天的浓缩液不会改变对产后补充的反应。

启示：产前补充可提高出生时母牛的性能和犊牛体重，而产后补充可提高生殖效率。