Studies on Compensatory Growth in Black Head Persian (BHP) Lambs

Abstract

A study was undertaken to investigate effects of underfeeding and re-feeding on growth peiformance of lambs. In the first 8 weeks of the study there were two treatments: Low (L) and high (H) planes of nutrition. In the last 8 weeks there were four treatments: continued low (LL), a change from low to high (LH), a change from high to low (HL) and continued high (HH) planes of nutrition. Low plane of nutrition consisted of ad libitum hay plus 100 g of concentrate per animal per day and high plane of nutrition was made up of hay ad libitum plus 400 g of concentrate per animal per day. In the first eight weeks, lambs on H treatment had higher growth rates, dressing percentages, and gut and carcass fats, lower proportions of lean, bone, gut fill, leanfat and lean:bone ratios than animals on L treatment. In the last eight weeks, lambs on LH grew faster than those on HH. When the whole period was considered (from start to 16 weeks), there was little difference in growth rate between animals on LH and HH treatments. At the end of 16th week, dressing percentages were 45.0, 51.6, 50.2 and 50.4, percentages of lean were 62.2,60.7,65.5 and 57.0, percentages offat were 14.0, -19.2,13.6 and 26.0 and those of bone were 23.8, 20.1, 20.9 and 17.0 for animals on LL, LH, HL and HH respectively. Lean growth for underfed re-fed animals was higher than for continuously well-fed animals. There were comparable profit margins between LH and HH animals as estimated from live weight gains.

Keywords: Compensatory growth, feeding, Balck Head Parsian, carc~ss composition

Tanzania J. Agric. Sc. (2007) Vol. 8 No. 1,.79 -86