Minimum length of the adaptation and collection period in digestibility trials with sheep fed ad libitum only forage or forage plus concentrate

Abstract

Two in vivo digestibility trials with sheep were conducted to identify the minimum period length of feeding a new diet to obtain reproducible values of nutritional variables onward and the minimum length of collection period as to obtain maximal precision for each variable. Trial 1 was conducted with ten Polwarth male sheep (34 ± 5 kg body weight (BW)) throughout three 21-day periods, in a completely randomized two-way crossover design. The animals were divided into two groups (Group A and B, n = 5 per group) which were fed ad libitum with a sequence of the following diets throughout the periods: Group A: hay - hay plus concentrate - hay; Group B: hay plus concentrate - hay - hay plus concentrate. The concentrate was included in a proportion of 0.33 of the total diet. The intake, and the faecal and urinary excretion were measured daily throughout the experiment. For evaluating rumen fermentation variables, in Trial 2 four Santa Inês male sheep (65 ± 5 kg BW) fitted with ruminal cannula were used. The animals were randomly divided into two groups (n = 2 per group), and the trial was conducted through four 21 days experimental period, in a three-way crossover design, using experimental diets and feeding management similar to Trial 1. The results indicated that, even though no clear or consistent steady-state condition was identified for rumen fermentation or urinary excretion variables, the adaptation period for measuring OM digestibility in in vivo trials with sheep fed ad libitum where the diet shifts from one of only hay to another containing concentrate, or vice-versa, should be at least 12 days long. Moreover, although no precision improvement was obtained by increasing the collection period above 1 day for measuring OM digestibility, the minimal length of collection period should be 4 days for measuring faecal excretion variables and 7 days for measuring urinary excretion variables.

Invited review: Nitrogen in ruminant nutrition: A review of measurement techniques

“…Rumen microbial populations profoundly change with changing diet composition (Fernando et al, 2010) and the rumen ecosystem requires time to recover from or adjusts to changes in diet regimens (Tajima et al, 2000;Monteils et al, 2012). It is generally assumed that the length of a typical adaptation period within changeover design experiments, 14 to 21 d, is sufficient for the manifestation of treatment effects on DMI and digestibility (Grant et al, 2015;Machado et al, 2016;Farenzena et al, 2017). However, evidence indicates that this duration can be shorter for components of the rumen ecosystem.…”

Use of Saccharomyces cerevisiae-based products and effects on rumen environment and performance of sheep subjected to dietary changes

“…The difference in ADG values of the Cultron X group in periods 2 and 4 can be explained by the better adaptation at the rumen level of animals supplemented with yeast culture, since the abrupt change in feeding without prior adaptation does not guarantee an appropriate digestion and ruminal fermentation (FARENZENA et al, 2016), indicating that these individuals go through feeding challenge periods less severely.…”

Productivity and carcass characteristics of lambs fed fibrous agricultural wastes to substitute grass

“…The lambs were provided the diets and water ad libitum and were weighed once a week. Feces were collected for 7 days during week 3 of the treatment period to calculate feed digestibility [18]. The feces were collected daily, weighed, and sampled using the procedure of Darlis et al [19].…”