Diet selection and feed intake by lambs under intermittent suckling and fed with total mixed ration containing three levels of crude protein

Abstract

Supplying a high-quality ration during preweaning phase can accelerate the rumen development and improve lambs performance. This study aimed to evaluate the diet selection and feed intake of Santa Ines and ½Dorper × ½Santa Ines lambs fed with total mixed ration (TMR) containing three levels of crude protein (CP) and managed under intermittent suckling up to weaning. A total of 67 lambs were uniformly distributed according to breed pattern, body weight (BW), sex and type of birth into three treatments: 18, 21, and 24% CP in TMR. The experiment started when lambs had 34 ± 10 days of age and 9.60 ± 3.07 kg BW, and lasted 60 days. The TMR was provided ad libitum in feedlot and was composed of 32.4% of corn silage and 67.6% of protein-energy concentrate, on a dry matter basis. Orts were collected and weighed daily, and its average particle size (APS) was assessed using the Penn State Particle Separator. The characteristics of orts did not differ (P>0.05) among CP levels and showed mean values of 8.03 ± 0.86% for particles >19mm, 50.23 ± 2.39% for particles between 7.8 and 19mm, 27.91 ± 1.55% for particles between 1.8 and 7.8mm, 13.83 ± 1.29% for particles <1.8mm, and 6.62 ± 0.35mm for APS. These results indicate a similar feeding selection pattern among treatments. Moreover, lambs had preference by concentrate feed, since the APS of TMR was 4.70mm on average. Daily dry matter intake on weight basis (364.1 ± 47.9 g/lamb/day) and relative to BW (2.08 ± 0.18% BW/day) were not affected (P>0.05) by CP levels. Thus, increasing CP level in TMR does not influence the diet selection neither feed intake by lambs under intermittent suckling management. However, our findings suggest that protein intake increases with CP level of TMR provided to them.