Comparative energy and protein utilization in kids and lambs

Abstract

S U M M A R YTwenty-eight male castrate kids and 28 male castrate lambs were assigned to a comparative slaughter experiment to compare energy and protein utilization. The experiment was conducted from January to March at Lincoln, New Zealand. Ten animals of each species comprised the initial slaughter group while the remaining 18 animals were randomly allocated to five feeding regimes. Animals were offered high-quality meadow hay for 13 weeks and then slaughtered. The energy retained in the body was regressed against metabolizable energy intake (MEI) to obtain estimates of maintenance energy requirement (ME m ) and efficiency of energy utilization for growth (k ) .Kids tended to have a higher ME m (0-44 v. 0-37 MJ ME/kg W°' 5 per day in kids and lambs, respectively) and a higher & g (0-28v. 0-22) though these differences were not significant. There was no difference between the species in the composition of gain of the fleece or hair-free body with a protein energy to gross energy ratio in the gain of 0-20. The fleece or hair-free body composition was similar for both species (initial 05lv. 048; final 036 v. 0-32; protein energy:gross energy, kids and lambs, respectively). Overall, the values for k f in both species were low and could not be explained solely by the composition of the gain.The efficiency of use of apparently absorbed amino acid (AA) for fleece or hair-free body protein deposition was higher for kids (0-52 v. 0-29) and, when the fleece or hair was included, the value increased markedly for lambs (0-50 v. 0-41, kids v. lambs, respectively). The protein energy apparently absorbed in the small intestine/MEI was not high or different between species (mean 018). The efficiency values for both species are low and not explained by the supply of protein relative to energy, which was not high.It was concluded that, with high-quality forage used to promote live weight gain, there was little difference between kids and lambs in the utilization of forage energy, and that the efficiency of utilization of absorbed protein for protein deposition was lower than expected in both species.

Liveweight gain and metabolisable energy requirements of young entire male Australian Rangeland goats in response to supplementation

“…2) and were within the range (267-485 kJ ME/kg MW.day) reported by McGregor (2005). This value of 372 kJ ME/kg MW.day is also comparable to the ME m reported for young Anglo-Nubian × feral and Angora × feral goats and Dorset Down × Coopworth lambs in New Zealand (370-440 kJ ME/kg MW.day; Alam et al 1991), but lower than the value of 489 kJ ME/kg MW.day estimated for indigenous goats by Luo et al (2004) and adopted by the NRC (2007). In contrast, while the current estimate of the ME requirement per unit of LWG (35 kJ/g) was within the range (24-54 kJ/g) reported by McGregor (2005), it was higher than that estimated by Ash and Norton (1987c) and Luo et al (2004;25 and 20 kJ/g of LWG respectively), which would imply that the efficiency of use of ME g was lower in the current experiments than the published estimates.…”

Fattening performance of Polish Lowland lambs related to protein level in the diet

“…The poorest energy utilization (K f = 0.27) was found when the ration contained 61.7 kJ metabolizable energy per gram of crude protein, while the best (K f = 0.43) was at a ratio of 73.8 kJ/g. Urbaniak (1986) found similar energy utilization by fattening Merino lambs fed a ration containing 14% crude protein, while Alam et al (1991) much worse utilization (0.22) by Dorset Down x Coopworth lambs.…”

The effect of the protein level in diets of Polish Lowland lambs on growth and fattening

“…The daily ME maintenance requirement of suckling lambs was calculated using the coefficient 418 kJ/kg 0 75 , according to Theriez et al (1982). A somewhat smaller value of this coefficient, 370 kJ/kg 0 75 is given for castrated rams by Alam et al (1991), while Hussein and Jordan (1990) found that suckling lambs use even up to 60-66% of the gross energy contained in consumed milk for the production of heat and only 34-40% of it is retained in their bodies. This high heat production in suckling lambs is thus an important factor determining maintenance requirements, which are greater in suckling than in weaned lambs.…”