Nitrate-nitrite toxicity in cattle and sheep grazing Dactyloctenium radulans (button grass) in stockyards

SUMMARYThe effects of species composition and sward structure on the ingestive behaviour of cattle and sheep grazing a mesic, low quality grassland in South Africa were investigated over the 1990–93 grazing seasons. Species composition had a significant (P < 0·05) effect on sheep bite size and on cattle and sheep bite rates but had no effect on dry matter intake rate (IR). Species composition could, however, affect IR over longer grazing periods than those used in the experiment.Sward structure had a major effect on ingestive behaviour. Cattle and sheep bite rates and cattle grazing time, were negatively correlated (P < 0·05) with plant height but positively correlated (P < 0·05) with sward greenness. Bite size and hence IR in cattle and sheep were strongly correlated (P < 0·001) with plant height. Cattle IR increased from 6 to 20g/min over the range of heights encountered and appeared to reach an asymptote at a plant height of 20–25 cm. Sheep IR, expressed per unit of body mass, increased from 0·01 to an asymptote or maximum of 0·13 g/min/kg at plant heights of 10–15 cm. For sheep there was evidence of a non-asymptotic functional response at some sites with IR being maximized at certain sward heights but declining thereafter. This suggests the possible existence of a third, quality dimension to the functional response on these low-quality grasslands.

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Birth weight, liveweight gain in early life, and subsequent gain in sheep and cattle

Australian Journal of Agricultural Research ◽

10.1071/ar9680837 ◽

1968 ◽

Vol 19 (5) ◽

pp. 837 ◽

Cited By ~ 5

Author(s):

ID Wardrop

Keyword(s):

Sex Differences ◽

Birth Weight ◽

Milk Production ◽

Growth Rates ◽

Early Life ◽

Significant Gain ◽

Sheep Grazing ◽

Cattle And Sheep

The relationships between birth weight, liveweight gain in early life, and subsequent gain of cattle and sheep grazing improved pastures were studied. In both species the correlations between liveweights at each age were highly significant. For female lambs, but not for males, birth weight was significantly correlated with the subsequent liveweight gain to 3 weeks, and this gain was significantly correlated with the subsequent gain to 17 weeks of age. These sex differences could be explained by the more variable growth rates of the female lambs. Ewe milk production and lamb milk intakes from birth to 3 weeks of age were significantly correlated with the liveweight gain over that period, but not with the subsequent gain. In cattle the correlation between birth weight and the liveweight gain to 6 weeks of age was non-significant. Gain from birth to 6 weeks was significantly correlated with gain between 6 and 36 weeks of age (weaning), but not with gain between 36 and 89 weeks (slaughter). The correlations between the gains, birth or 6 weeks to weaning, with the subsequent gains to slaughter were highly significant.

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