Boards of artificial pasture were prepared by threading the top two leaves of tillers from either ryegrass or kikuyu grass, in their vegetative stage of growth, through 5-mm-diameter holes in pressed hardwood sheets. The holes were spaced in rows from 10 to 50 mm apart, and, with one, two or three tillers per hole, tiller density ranged from 346 to 25 980/m2. Sward height was varied by pulling tillers different distances through the holes before they were fastened to the underside of the boards, and the mass of herbage dry matter ranged from 0.04 to 7.61 t/ha. In series I experiments, the effects of sward characteristics on ingestive behaviour of two sheep were examined, whereas, in series I1 experiments, pastures that were consumed at different rates were offered in pairs and the preference of one sheep observed.The rate of pasture intake was related to sward height only when tiller density was constant and to herbage mass per unit volume (bulk density) only at similar sward heights. Intake rate was better described by herbage mass per unit area but, at herbage availabilities of less than 1 t/ha, intake rate was several-fold greater when sheep grazed tall, sparse pastures than short, dense pastures. The best predictor of pasture intake rate was herbage mass per area effectively covered by one bite.Intake per prehending bite declined with a reduction in both sward height and density, and was also best described by herbage mass per area effectively covered by one bite. Prehending bite rate doubled as intake per bite declined from 200 to 10 mg dry matter. The rate of jaw movements during grazing was virtually unaffected by sward characteristics; prehending bites accounted for 20% of jaw movements when intake per bite was 200 mg dry matter and 80% of jaw movements with short, widely spaced swards.When two pastures with different sward characteristics were offered together, sheep generally preferred the one they could eat faster.*Part I, Aust.

No abstract

The present study revealed that CD affects a wide range of daily activities and that gluten consumption may be more common than anticipated with possible consequences on health.

I. Results of 298 nitrogen balance studies from experiments with male cross-bred lambs, ranging in weight from 3 to 38 kg, which had been either fasted, or fed entirely on liquid diets of varying protein content at various energy intakes up to ad lib. intake, were used to quantitatively describe the effects of the amount and quality of absorbed protein, energy intake and live weight on N balance and total N requirement of lambs.2. When N intake was less than the amount required, N balance was independent of energy intake, but linearly related to absorbed N and metabolic body-weight (live eight""^). In the fitted relationship, the coefficient of absorbed N was shown to be an estimate of the biological value of absorbed protein and the coefficient of metabolic body-weight was an estimate of the loss of endogenous N in both urine and faeces. For the milk-based diets used in the experiment biological value was 0'72 and the total endogenous N loss in urine and faeces was 148 mg N/kg075 per d. 3.When N intake was in excess of the amount required, N balance in lambs of a constant live weight increased linearly with metabolizable energy (ME) intake, at a rate that decreased with increasing live weight. Similarly at constant ME intake, N balance was a curvilinear decreasing function of metabolic body-weight. When N balance was expressed per unit metabolic body-weight, it was constant for lambs of all weights when ME intake was about 0.23 M J/kg0'76 per d, but it decreased linearly with increasing metabolic body-weight for ME intakes above this level.4. N balance of fasted lambs was several times less than predicted by either of the relationships established for fed animals, and was found to be linearly related to metabolic bodyweight.G . The effects of enerm intake and live weight on the total N requirement of lambs were -_ -determined. When total N requirement was expressed per unit of energy intake, it was found to be constant at 0-9 g N/MJ ME for all lambs irrespective of live weight when ME intake was 0.23 MJ/kg@75 per d. However, as ME intake/unit metabolic body-weight was raised above this level, N requirement/unit ME intake increased for lambs weighing less than c. 23 kg, but decreased for heavier animals.

In experiment 1, potential intake rates of several dried forages, varying widely in nutritive value, were measured by offering each alone to six hungry sheep for eight, separate 1-min periods. Intake rates ranged from 5.5 to 26.1 g/min, but, within each forage, it varied little between sheep (c.v. 13%) or between measurements with the same sheep (c.v. 8%). The forages were then offered in pairs in separate containers and preference for one forage was defined as the percentage of total intake derived from that forage. With the exception of a dried clover pasture, preference for a forage was strongly related to the rate at which it could be eaten. Reducing the length of wheaten straw particles from 30 to 10 mm increased intake rate from 5.5 to 12.4 g/min and resulted in an absolute preference for the short material. The mean preference for a forage over all comparisons was more strongly correlated with intake rate of the forage (r2 = 0.87) than with in vitro digestibility of organic matter (r2 = 0.30). In experiment 2, two wheaten straws and two wheaten hays were each chopped to two lengths and, within each forage, mixed (w/w) in the short : long ratios of 0 : 1, 1 : 2, 2 : 1 and 1 : 0. Mean intake rates were 7.3 and 12.5 g/min for the two straws and 15.7 and 23.2 g/min for the two hays. Within each forage, all mixtures were offered in pairs to establish preference. The slopes of regression equations relating preference (%) to intake rate (g/min) were 21.4, 17.0, 5.9 and 2.7 (%.min/g) for the four forages as mean intake rate increased from 7.3 to 23 2 g/min, which indicates that discrimination between forages with the same difference in intake rate was greater when mean intake rate was low. In experiment 3, finely ground clover pasture, lucerne hay, wheaten hay or wheaten straw were added to a base diet of either chopped lucerne or wheaten straw in the ratio 1 : 10. Although the additive had little effect on intake rate, sheep preferred lucerne to clover pasture and wheaten hay to wheaten straw. Equations developed from the results of experiment 2 to predict the preference for one forage over another on the basis of their relative intake rates, showed fair agreement with observations from experiment 1, particularly when the effects of acceptability factors such as taste, odour or feel were translated into differences in potential intake rate.