Seasonal variation of voluntary food intake and metabolic rate in three contrasting breeds of sheep

Abstract

1994). Seasonal variation of voluntary food intake and metabolic rate in three contrasting breeds of sheep. AbstractVoluntary food intake (VFI) of chopped timothy hay and metabolic rate were each measured in each month of the year in six non-breeding ewes of each of three breeds. Metabolic rate was measured using indirect calorimetry over a range of food intakes and adjusted for intake to an estimated maintenance metabolic rate (MMR). The breeds compared were the Dorset Horn (DT), Scottish Blackface (BF) and Shetland (SH), the first being less seasonal in reproductive and other characteristics than the other two which are hill or northern latitude breeds. There was significant overall variation between months in VFI which was higher in the summer (July to September) than in the winter (December to February) months (P < 0-001). There was a significant breed X month interaction (P < 0-01), the seasonal effect being most strongly observed in the BF and SH ewes, whose VFI in summer was proportionately 0-1 greater than the year-round mean but was 0-1 lower in the winter. The DT ewes showed much less seasonal variation in VFI. There was no overall difference in VFI between breeeds (DT: 43-7; BF: 49-5; SH: 48-1 g dry matter per M 075 live weight per day, P > 0-1). Although MMR varied significantly between months (P < 0-001), there was no systematic variation between summer and winter. There was no significant breed X month interaction, but the MMR differed significantly (P < 0-001) between breeds giving a high overall MMR in BF (DT: 322-7; BF: 356-6; SH: 324-5 kf/kg M 075 per day). No significant correlation existed (P > 0-05) between the monthly mean MMR and VFI in any of the breeds. The causal relationship between seasonal cycles of basal metabolic rate and VFI is questioned.

A comparison of voluntary intake and in vivo digestion in guanacos (Lama guanicoe) and sheep given fresh grass

“…The intake results for sheep obtained during this experiment were also slightly lower than those recorded by Warmington et al (1989) but are in keeping with other reports from studies with sheep (Aitchison et al, 1986;Domingue et al, 1991;Iason et al, 1994). However, they are substantially lower than those given in previous reports of comparisons between camelids and sheep.…”

“…For example, the daily intakes of the sheep during the current trials ranged from 17 to 19 g/kg live weight, much less than the corresponding figure of 23 g/kg live weight cited in the review by San Martin and Bryant (1989). Such discrepancies, together with reports of significant differences in intake between different breeds of sheep (Mann et al, 1987;Iason et al, 1994) indicate that care must be taken when extrapolating from this type of comparative study. Such discrepancies, together with reports of significant differences in intake between different breeds of sheep (Mann et al, 1987;Iason et al, 1994) indicate that care must be taken when extrapolating from this type of comparative study.…”

The growth and development of nine European sheep breeds. 1. British breeds: Scottish Blackface, Welsh Mountain and Shetland

“…There are however values quoted for the mature weight of Shetland sheep (Hammond, 1932;Thomson and Aitken, 1959;Wilson, 1976;Bowie, 1987;Vipond et al, 1987;Iason et al, 1994). There are however values quoted for the mature weight of Shetland sheep (Hammond, 1932;Thomson and Aitken, 1959;Wilson, 1976;Bowie, 1987;Vipond et al, 1987;Iason et al, 1994).…”

“…Aspects of the growth of the Scottish Blackface and Welsh Mountain breeds have been reported (e.g. There appear to be no published reports of the growth of purebred Shetland lambs though there are a number of reports relating to adult animals (Elwes, 1913;Hammond, 1932;Langlands et al, 1963;Wilson, 1976;Bowie, 1987;Vipond et al, 1987;Iason et al, 1994). However, from this extensive bibliography only three studies reported absolute (and hence usable) values for both growth rate and carcass composition over a range of weights.…”

Seasonal variations in physiological and behavioural parameters in a bachelor group of stallion ponies (Equus caballus)

“…Ruminants, for example, show seasonal changes in both reproductive and non-reproductive physiological and behavioural characteristics (Mitchell et al, 1976;Pratt et al, 1986); metabolic rate and appetite have been observed to reduce during the winter and increase during spring and summer (Heydon et al, 1993) and similarly, reproductive activity in sheep increases on exposure to short day length (Hafez, 1952). This seasonality is thought to reflect an evolved adaptation by the ruminant to ensure that the most nutrient-demanding reproductive and growth periods coincide with the seasons of food abundance and vice versa (Iason et al, 1994). Horses have also evolved under similar environmental pressures and, thus, it would be expected that similar seasonal adaptations of reproduction, appetite, growth and behaviour should also occur for this non-ruminant.…”