Sheep numbers required for dry matter digestibility evaluations when fed fresh perennial ryegrass or forage rape

作     者：Xuezhao Sun Linda Krijgsman Garry C.Waghorn Holly Kjestrup John Koolaard David Pacheco 

作者机构：Grasslands Research CentreAgresearch Limited DairyNZ Limited 

出 版 物：《Animal Nutrition》 (动物营养（英文版）)

年 卷 期：2017年第3卷第1期

页      面：61-66页

核心收录：

学科分类：0710[理学-生物学] 090502[农学-动物营养与饲料科学] 0905[农学-畜牧学] 0906[农学-兽医学] 09[农学] 

基　　金：a part of a large project funded by the Ministry for Primary Industries of New Zealand under the Sustainable Land Management of Agricultural Climate Change(SLMACC) programme the New Zealand Pastoral Greenhouse Gas Research Consortium(PGgRc) under the Low GHG feeds programme 

主　　题：Sheep Digestibility Fresh forage Sample size 

摘      要：Research trials with fresh forages often require accurate and precise measurement of digestibility and variation in digestion between individuals, and the duration of measurement periods needs to be established to ensure reliable data are obtained. The variation is likely to be greater when freshly harvested feeds are given, such as perennial ryegrass(Lolium perenne L.) and forage rape(Brassica napus L.),because the nutrient composition changes over time and in response to weather conditions. Daily feed intake and faeces output data from a digestibility trial with these forages were used to calculate the effects of differing lengths of the measurement period and differing numbers of sheep, on the precision of digestibility, with a view towards development of a protocol. Sixteen lambs aged 8 months and weighing 33 kg at the commencement of the trial were fed either perennial ryegrass or forage rape(8/treatment group) over 2 periods with 35 d between measurements. They had been acclimatised to the diets, having grazed them for 42 d prior to 11 days of indoor measurements. The sheep numbers required for a digestibility trial with different combinations of acclimatisation and measurement period lengths were subsequently calculated for 3 levels of imposed precision upon the estimate of mean dry matter(DM) digestibility. It is recommended that if the standard error of the mean for digestibility is equal to or higher than 5 g/kg DM, and if sheep are already used to a fresh perennial ryegrass or forage rape diet,then a minimum of 6 animals are needed and 4 acclimatisation days being fed individually in metabolic crates followed by 7 days of measurement.