The effect of herbage yield and allowance on growth and carcass
characteristics of weaned lambs
K.T. Jagusch, P.V. Rattray, T.W. Oliver, N.R. Cox
Ruakura Animal Research Station, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1979, 39: 254-259
In two experiments conducted in 1976-7 and 1977-8 with ryegrass-
white clover pastures yielding 2 to 5 t DM/ha, groups of 10-week-old
lambs were offered 2, 4 or 6 kg DM/lamb/day (n=36/group) over 8 weeks.
Herbage allowance, and not pasture yield, digestibility, accessibility
to herbage or season, was the major factor affecting growth rate and
thereby slaughter weight. Carcass, skin, and peri-renal fat weights and
eye muscle area differences were directly related to differences in
final slaughter weight. Mitscherlich equations (y = a + brx),
where y = growth rate and x = herbage allowance, showed that near
maximum growth rates of 150 ± 17 g/day were achieved at allowances of
5.0 kg DM/lamb/day. The nature of the response was suggested to be due
to both the opportunity for selection and dominance-behavioural
structures related to grazing territories. The requirements of the lambs
were described by the regression equation: y = 171 - (195 x
0.64x).
Keywords: NZSAPAB;
Last Updated 12-09-1998
