Energy supplements for beef heifers on cool season pastures - a database analysis

ABSTRACT: Pooled data analysis is an analytical method that combines results from multiple studies. This technique provides a more robust estimate of the effects of an investigation. We performed a database analysis from seventeen experiments developed at Federal University of Santa Maria, Rio Grande do Sul state, Brazil, between 1999 and 2017 to characterize individual performance per area and stocking rate with or without supplementation of replacement heifers grazing winter pastures. Data were separated into two groups: with and without energy supplement provision, and into five subgroups based on supplement levels. Heifers from both groups were maintained under similar forage biomass and leaf blade allowance. Statistical analyses were run on R software using a ‘meta’ package. Supplement supply increased average daily gain and gain of body condition scores by 11.1% and 20.0%, respectively. Supplement levels higher than 1.2% of body weight resulted in higher weight gain per area, with the stocking rate increasing with higher supplement levels.

摘要：合并数据分析（pooled data analysis）是一种整合多项独立研究结果的分析方法，可对研究效应提供更为稳健的评估结果。本研究整合了巴西南里奥格兰德州圣玛丽亚联邦大学1999年至2017年间开展的17项实验的数据库，旨在刻画冬季牧场放牧后备母牛在添加与不添加能量补充饲料时的单位面积生产性能与载畜率（stocking rate）。研究将数据分为两组：添加能量补充饲料组与未添加能量补充饲料组，并依据补充饲料用量划分为五个亚组。两组试验牛均维持在相近的牧草生物量与叶片供给量条件下开展试验。统计分析采用R软件及其「meta」包完成。补充饲料供给可使平均日增重与体况评分增益分别提升11.1%与20.0%。当补充饲料用量超过体重的1.2%时，单位面积增重更高，且载畜率随补充饲料用量提升而升高。