Evaluvation of artificially dried grass as a source of energy for sheep:II. The energy value of cocksfoot, timothy and two strains of rye-grass at varying stages of maturity

Abstract

There is relatively little detailed information concerning the value of grass and grassland products as sources of energy for ruminants. Armsby and his associates (Armsby & Fries, 1915;Armsby, Fries & Braman, 1916;Armsby & Fries, 1918) studied the utilization of the energy of alfalfa, clover and timothy hays by sheep when fed at the maintenance level, using a respiration calorimeter. Mitchell, Kammlade & Hamilton (1928) examined the relative energy values of alfalfa, clover and timothy hays for the maintenance of sheep, using the carcass slaughter technique. The energy values of some artificially heat-dried grasses fed to sheep in respiration chambers have been given by Blaxter & Graham (1955) and preliminary results of an investigation on freeze-dried herbage fed to sheep in a gradient-layer calorimeter have been reported by Corbett, Langlands & Puller (1962). Heinzel (1943) fed small supplements of fresh and artificially dried grass to sheep in respiration chambers receiving a basal diet of clover-grass hay.The first paper of this series (Waite, Johnston & Armstrong, 1964) referred to the chemical composition and digestibility by sheep of rye-grass S 23 cut at four stages of maturity, cocksfoot S 37 and timothy S 48 each cut at three stages of growth and of rye-grass S 24 cut at two stages of growth. This paper gives the results of calorimetric experiments carried out to measure the energy value of the dried grasses. Preliminary reports of some of the findings have been published (Armstrong, 1960(Armstrong, , 1963. EXPERIMENTALGrasses. The grasses have already been described by Waite etal. (1964).Sheep. During the first year's experiments in which the four cuts of rye-grass S 23 were given, * Present address: University of Newcastle upon Tyne. eight wether sheep aged 3J-5 years and of mixed breed, and four Down-Halfbred cross wethers aged 1\ years were used.In the subsequent experiments during which the cuts of cocksfoot, timothy and rye-grass S 24 were given, the sheep were all Down-Halfbred cross wethers, aged 3 years, four of which had been used in the earlier experiments with rye-grass S 23. All the sheep were well trained to the regime of respiration chamber experiments before the work began.Four sheep each equipped with a permanent rumen fistula were used to obtain rumen liquor samples which would be characteristic of the rumen liquor of the sheep given the various grasses. Two of these sheep were among those used in the calorimetric experiments with rye-grass S 23.The sheep were not shorn until all the experiments had been completed. Plan of experiment(i) The four cuts of rye-grass S 23. In the first instance each of the four cuts was given to each of two mature sheep at five different levels of intake ranging from approximately half maintenance (level a) to that considered close to maximal voluntary intake (level e). For any one sheep the order of receiving the various levels was decided from a random selection of models fulfilling the condition that level o or level b (the two lowest levels) did not fo...

Availability of Energy to Sheep from Artificially Dried Grass at Progressive Growth Stages

“…From the forgoing discussion it appears that the results obtained in the present study, in general, are in agreement with those of others (for instance, Armstrong, 1964) in showing the effect of the stage of growth of artificially dried grass on the availability of energy.…”

“…Such calorimetric studies on dried grass have been reported by Heinzl (1944), Blaxter & Graham (1955, 1956, Corbett et al (1962), Prabucki (1963), Armstrong (1964), Schoch et al (1964), Ekern et al (1965), Blaxter et al (1971) and Wainman et al (1972).…”

Seasonal variation in methane emission from dairy cows and breeding ewes grazing ryegrass/white clover pasture in New Zealand

“…The only measurements reported for grazing cows is the work of McCaughey et al (1999) with lactating beef cows grazing two different pasture types (alfalfa-grass, or meadow bromegrass), where methane emission measured with the SF6 technique averaged 267-293 g/day for animals estimated to be consuming 9.7-11.4 kg DM/day. Similarly, the emission rates for the ewes of 26-32 g/day fell within the range reported for calorimetric studies by Blaxter & Wainman (1961) and Armstrong (1964). The methane emitted per unit of DM intake appears to be higher in the McCaughey et al (1999) experiments than in the present work.…”

Comparison by direct animal calorimetry of the net energy values of an early and a late season growth of herbage

“…Starch equivalents calculated from digestible nutrient contents were virtually identical and both values were higher than those actually determined. Armstrong (1964) would equate zero M.E. in the two diets, given in Table 5, has been calculated from a number of empirical expressions recently published.…”