THE EFFECT OF QUALITY OF DIET ON FEED INTAKE, FEED DIGESTIBILITY, AND GROWTH RATE OF LAMBS IN AMBIENT TEMPERATURES or 20 AND 30 C

Abstract

A study has been made on the effect of feed quality on feed intake and live-weight gain in lambs housed at different ambient temperature. Sixteen Border Leicester x Merino whether lambs aged 7 months and weighing 33jl.5kg were allocated to a 2x2 factorial structure in a randomized block design. The factors were temperature (20 and 30°C) and diet (diet I contained low protein and high fibre, and diet 2 contained high protein and low fibre). Respiration rate (RR), rectal temperature (RT), feed intake, digestibility, live weight gain (LWG) and feed conversion ratio (FCR) were estimated. On both diets, lambs held at 20 °C had lower RT, higher intake, higher LWG and lower FCR than those at 30 °C. Lambs given diet 2
had higher feed intake, higher feed digestibility, higher LWG and thus lower FCR than those given diet 1. There was no significant difference in RT between diets. Temperature did not affect feed digestibility. There were significant interactions between temperature and diet for N intake and RR but not for other indices of lamb’s performance. Lambs housed at 30°C were selecting feed with higher N content than that offered. At 20 °C, the lambs given diet 2 had a very significantly lower RR than that those given diet l. However, the difference was, although
still significant, mush less pronounced at 30 °C .