Effects of abomasal protein and energy supply on wool growth in Merino sheep

Abstract

The relative importance for wool growth of energy-yielding nutrients compared with amino acids required for incorporation into wool proteins was assessed in an experiment in which most nutrients were supplied via the abomasum. Nine nutritional treatments, providing three levels of protein (53, 99 and 145 g/day) to the intestines at three levels of energy (5.2, 7.5 and 9.7 MJ/day), were given to 12 Merino sheep during three consecutive periods of 3 weeks in a balanced lattice design. Abomasal nutrients consisted of varying proportions of casein, whole milk, glucose and glycerol. There was a large effect of protein supply on all components of wool growth, but there was no significant effect of energy. There was a significant interaction between the effects of protein and energy supply on diameter, length growth rate and volume of wool, but it was small relative to the main effect of protein. Extra energy appeared to enhance wool growth at the highest level of protein but reduce it at the lowest level of protein. The concentration of urea, cystine, methionine and other essential amino acids in plasma increased with protein level. Increasing energy supply reduced the concentration of urea and essential amino acids in plasma but not that of cystine or methionine. The experiment confirmed the major role of amino acid supply in controlling wool growth but indicated that there may be a small interaction with energy supply.

Fish-meal supplement for severely undernourished ewes: effects on apparent digestibility and utilization of the diet

“…Similar positive response of wool growth to protein or purified amino acids supplementation was reported by Dove and Robards (1974) and Munro (1990 and1992). S-amino acids) for wool synthesis.…”

Effect of lambing policy and ewe breed cross on wool growth patterns and wool quality

“…37 al. 1984 and by variation in pasture availability and hence ewe intake (Allden 1979;Sumner 1983;Reis et al 1992). In most situations these are confounded to a considerable degree because the short days of winter coincide with periods of low pasture availability and quality.…”

Effects of replacing rolled barley grain with wheat dry distillers' grains with solubles in Merino sheep rations

“…There is limited research which has investigated the effects of feeding distillers' grains to Merino sheep on wool production; however, numerous studies have observed improvements in wool traits in sheep fed dietary supplements with similar nutritive value to distillers' grains (Reis et al, 1992;Datta et al, 1999;White et al, 2000;Habib et al, 2001;Silva et al, 2007). It was difficult to determine in this study whether the improvements in wool growth 108 A. S. Graham et al…”