Myoglobin and haemoglobin concentrations were determined in the m. longissimus dorsi of 133 Dorset Horn × Corriedale lambs, varying in age from 98 to 310 days, and killed at a live weight of 32 kg. Analysis of the data showed that age, over the period studied, was not a critical factor in determining the myoglobin concentration within the muscle. The average pigment level in the muscle of ewes was some 20% greater than in ‘cryptorchids’ and approximately 10% greater than in wethers. Haemoglobin was found to represent about 40% of the total haem pigment.

Body temperature and respiratory rate were investigated during the hottest months of the year in five docked and five undocked fattailed Awassi rams, together with the effect of month and docking on these physiological variables.

Month had significant effects on both variables in the two groups. Diurnal variation in rectal temperature was significant in both groups.

Docked rams maintained significantly lower rectal temperatures and respiratory rates than their controls.

Haemoglobin types of two Indian breeds of sheep were related to ram and ewe fertility and lamb mortality. Rams with Hb B type had a significantly higher number of lambs born to ewes mated to them. Ewe fertility and lamb mortality were better, but not significantly so, in animals with Hb B type.

In Merino rams studied over three seasons in New South Wales scrotal cover was correlated with face cover (0·29) and cover on points (0·16). Scrotal length was positively correlated with scrotal wool cover (0·17) and cover on points (0·28).

Sixty-four young male Sudan desert lambs were group-fed for 87 days on four diets, all containing approximately 10% crude protein. The four diets contained 0, 1·3, 1·7 and 2·7% urea, respectively.

Average daily gains were 0·15, 0·14, 0·14 and 0·13 kg; feed conversion ratios (kg of feed required to produce 1 kg live-weight gain) were 7·26, 8·14, 8·92 and 7·92; dressing percentages were 43·6, 42·1, 44·1 and 42·3.

Digestibility trials with lambs fed on diets with 0 or 2·7% urea gave higher digestibility coefficients for crude fibre and nitrogen-free extract for the urea-supplemented lambs. Crude protein digestibility and nitrogen retention values were lower for urea-supplemented lambs.

Animal Production, Volume 13, part 1, pp. 193–195

A note on the haem pigment concentration of lamb as influenced by age and sex

by D. A. Ledward And W. R. Shorthose

C.S.I.R.O. Division of Food Preservation, Meat Research Laboratory, P.O. Box 12, Cannon Hill, Queensland, 4170, Australia.

In this article, ‘The factor used to convert acid haematin to total haem pigment concentration should be 17·7 not 35·4. Thus all the haem pigment concentrations quoted are double their true values. This error in the absolute concentrations of both myoglobin and haemoglobin does not affect the statistical analysis of the results and the conclusions reached regarding the influence of age and sex on myoglobin concentration.’