The assessment of a crop husbandry technique in terms of animal production

Abstract

SUMMARY1. The energy value of three hays cut at three stages of maturity was. measured by calorimetric methods and, in addition, the amounts of the hays consumed voluntarily by sheep were measured. Voluntary intake was alsa measured when 200, 500, 800 and 1,200 g. of pelleted concentrates were given.2. The metabolisable energy values of the three hays measured at the-maintenance level were 2·45, 2·26 and 2·16 kcal./g. for cuts 1, 2 and 3-respectively (cut 1 being the earliest). The net energy values for fat production were 0·96, 0·85 and 0·68 kcal./g. respectively.3. The apparent digestibility of the hays fell with increasing intake, but supplementation with concentrates increased their apparent digestibility.4. The voluntary intake of the hays given as the sole food was 70, 62 and 57 g./kg. W0·73 for the three cuts, respectively. When concentrates were given in increasing amounts, the intake of cuts 2 and 3 increased to maxima of 65 g. and 64 g./kg. W0·73 respectively and thereafter declined. With cut 1, intake of hay declined even with the smallest intake of concentrates. Voluntary intake of the hays was maximal when the protein content of the whole ration was 8·5%.5. When no supplement was given the digested energy per sheep per day supplied by cut 1 was 64% greater than that supplied by cut 3. When 800 g. concentrates were given, however, the ration including the early cut of hay provided only 2% more energy than that including the late cut.6. It is shown that if hay were given as the sole food cut 3, which produced 57% more weight of crop per acre, would provide 38% more metabolisable energy/acre and 11% more net energy (starch equivalent)/acre than would cut 1. The late cut would also enable 92% more sheep to be kept feeding to maximal appetite on an acre of produce. However, the total live-weight gain per acre would be only 25% of that obtained with thefirstcut.7. Comparable calculations have been made for the experiments in which concentrates were given. It is shown that here too optimal times of cutting can only be assessed in terms of estimates of animal production.

The voluntary intake and utilization of roughage–concentrate diets by sheep. 2. Barley and soya bean meal supplementation of hay diets

“…These results concur with those of Blaxter and Wilson (1963), Murdoch (1964) and Crabtree and Williams (1971) in showing that the voluntary intake of hay in hay-concentrate diets is a function of hay quality, proportion of concentrate in the diet and concentrate protein level. Donefer et al (1963) found that when lambs were given ground, pelleted diets compounded from varying proportions of barley and lucerne, the voluntary intake of the total diet declined as the percentage of barley increased, but digestible energy intake remained approximately constant.…”

“…However, at the higher levels of barley feeding (B^.Bi) the substitution rates observed were of the same order as those recorded by the other workers. The differences between results in the hay intake response to barley feeding when soya bean meal was not given may be related to differences in the quality of the hays used (Blaxter and Wilson, 1963). The digestibility and crude protein content of the hays used by the other workers were higher than for the hay used in the present study.…”

Voluntary intake of low-protien diets by ruminants: I. Intake of food by cattle

“…That level of protein in the diet, below approximately 10 % crude protein, affects voluntary intake of food by ruminants is now well established (Campling et al 1961Blaxter & Wilson, 1963;Elliott & Topps, 1963c)). Confirmation of this finding was obtained in the present study.…”

Beef production from silage 1. The voluntary intake and live-weight gain of beef cattle given red clover silage

“…Developmen s in additive technology indicate a potential for formic acid/formaldehyde mixtures since formaldehyde has been shown not only to reduce fermentation (Wilkins, Wilson and Woolford, 1974) but also to tPresent address: Agricultural Research Council, 160 Great Portland Street, London WIN 6DT. increase the supply of amino acids from silage to the animal (Beever, Thomson, Cammell and " • 10771 Differences in voluntary intake and animal performance, apparent when forages are given as the sole feed, are much reduced in the presence of a supplement (Blaxter and Wilson, 1963 …”