Food intake and diet selection in sheep: the effect of manipulating the rates of digestion of carbohydrates and protein of the foods offered as a choice

Abstract

An experiment was designed to investigate whether the degree of synchrony between the rates of digestion of carbohydrates and N of foods offered as a choice would have an effect, through their consequences, on the short-and long-term diet selection of sheep. Four foods (RL, RH, SL and SH) with the same high metabolizable energy, and similar high metabolizable protein contents were made into pellets. Foods RL and RH were based on a rapidly fermentable carbohydrate source and foods SL and SH on a slowly fermentable carbohydrate source; within each source one food (RL or SL) had a low, and the other (RE or Sa) a high, men-degradable protein (RDP) content. The foods within a carbohydrate source were offered either singly or as a choice (RIJRH or STJSH) to eleven rumen-fistulated mature sheep. The design was two 3 x 3 Latin squares (replicated once) with 5-week periods; squares consisted of two single foods and their respective choice. Weeks 1 , 3 and 5 were considered to be controls, and weeks 2 and 4 used for m e n infusions of either urea or fructose infused over 4h (10.00-14.00 hours). Food intake (FI) and diet selections @S) were recorded daily and every 2 h (08.00-16.00 hours) on days 2-5 of each week; m e n pH and NHJ concentrations were also measured during these time intervals of day 5. As expected, feeding treatment affected significantly the rumen measurements: m e n NHs concentrations were higher on foods RH and SH, and m e n pH lowest on RL. Daily FI was lowest on treatments SL and choice SI/& The mean daily proportion of the low-RDP food in the selected diet was lower when the carbohydrate source was rapidly (choice R~H ) rather than slowly fermentable (choice SIJSH); this was consistent with the experimental hypothesis. Short-term infusions affected further rumen variables (in the expected directions), irrespective of feeding treatment. However, DS over the 4 h infusion period were unaffected; these short-term DS were consistent with the ones selected over the longer term (daily). The results suggest that the long-term (daily) diet selection of sheep may be affected by the degree of synchrony of energy and protein to the m e n . The fact that diet selections were not altered further by short-term manipulations of these supplies might reflect inadequacies of the methodology (infusions) adopted here.Diet selection: Food intake: Rumen: Rumen-degradable protein: Sheep It has been suggested that one of the objectives of the diet selection of ruminant animals is to maintain a fit and adaptive rumen (Cropper, 1987;Parsons et al. 1994; Cooper et al, 19953). This strategy would be expected to assist the animal in achieving its ultimate goal of meeting its requirements for energy and nutrients, and would require certain aspects of the rumen environment to remain at optimal levels or at least within an acceptable range of conditions. Cooper et al. (1995a,b) hypothesized that the rumen conditions that may have a significant effect on the diet selection of ruminants would be those related to the consequences of f...

Effects of Birth Weight and Feeding System on Fattening Performance and Feeding Behaviour of Karayaka Male Lambs

“…Therefore, the environmental temperature probably had a similar affect on the intakes of dry matter, feed ingredients and nutrients of TMR-and FCF-fed lambs in the present study. High dietary protein or energy concentration in fattening lamb diets may result in the occurrence of digestive disturbance (Kyriazakis and Oldham, 1997), abnormal or erratic feeding behaviour (Askar et al, 2006;Favreau et al, 2010). In the present study, no occurrence of these problems in FCF-fed lambs was observed probably due to the fact that TMR-and FCF-fed lambs had a similar crude fibre intake.…”

“…A higher the daily weight gain may be related to the amounts of ingested protein and energy in the FCF systems was theoretically in excess of nutrient requirements for fattening (NRC, 2007) due to the fact that the FCF system increased the dry matter, energy and protein intakes (Tables 2 and 4). Many factors, such as inherent characteristics of the animal and long-or short-term environmental and managemental conditions have been reported to affect diet selection and behavioral responses as well as fattening performance (Kyriazakis and Oldham, 1997;Sahin et al, 2003;Kaya et al, 2011). Kaya (2011) reported that the performance of lambs in outdoor in hot climate condition could be inferior to that of lambs in a more controlled environment because the outdoor lambs would be exposed to heat stress.…”

Effects of feeding green forage of sulla (Hedysarum coronarium L.) on lamb growth and carcass and meat quality

“…The higher sulla intake found in this experiment could be related to the more favourable chemical composition observed in legume forage, which was higher in protein and non-structural carbohydrates (270 v. 158 g/kg of DM for sulla and ryegrass, respectively; data not shown in the tables) and lower in structural carbohydrates in comparison with ryegrass. Indeed, it is well established that the degree of synchrony between the rates of fermentation of carbohydrates and degradation of protein in the rumen influences diet selection and intake of ruminants (Kyriazakis and Oldham, 1997). Moreover, Burke et al (2004) suggested that the greater DM intake of sulla forage is linked to the greater ratio of degradable-to-structural carbohydrates, resulting in a faster rate of breakdown in the rumen, and subsequent outflow to the intestine.…”

Cattle and sheep develop preference for drinking water containing grape seed tannin

“…Heifer initial response to increased CP intake on days 15 and 16 of the trial, which was decreased intake of tannin solutions, may have been because of short-term disruption of rumen digestion of CP and carbohydrates (Kyriazakis and Oldham, 1997;Reynolds and Kristensen, 2008) which may have stabilized after day 17.…”