Comparative studies of the influence of sward conditions on the ingestive behaviour of cows and sheep

Abstract

Separate groups of non-lactating cows and wether sheep grazed at similar herbage allowances for two successive 5-d periods on swards that had previously been grazed frequently or infrequently with the intention of creating differences in canopy structure. Measurements were made of sward structure and composition, ingestive behaviour and diet composition. The preliminary treatments had little effect upon either sward conditions or animal behaviour.Herbage mass was reduced from 4020 kg dry matter (DM) ha"' to 3290 kg DM ha"' on average over a 5-d grazing period as a consequence of the relatively low grazing pressure imposed. This resulted in a mean decline in intake per bite of 28%, and the changes for cattle and sheep did not differ significantly. However, there was a marked difference in the other behavioural responses of the two species; in the sheep biting rate fell and grazing time increased with declining herbage mass, particularly in the sward previously grazed infrequently, whereas the changes in the cattle were small. Differences in the botanical composition ofthe herbage eaten by cattle and sheep were minor, but there was a small but consistent advantage to the sheep in the digestibility of the herbage eaten.In the first of the two periods the variation in surface height after grazing was substantially greater for sheep-grazed than for cattle-grazed

Comportamento de ovinos em capim-tanzânia sob lotação rotativa com quatro níveis de suplementação concentrada

“…Além disso, é possível também que a grande freqüência de defecação nos níveis de suplementação de 1,2 e 1,8% PV tenha contribuído para a redução no tempo de pastejo dos animais, em virtude da rejeição da forragem contaminada pelas fezes (Forbes & Hodgson, 1985).…”

“…A taxa de bocado e o tempo de pastejo dos animais que não receberam suplementação foram inferiores (28 bocados/minuto) e superiores (595,8 minutos/dia), respectivamente, aos relatados por Forbes & Hodgson (1985) em trabalho sobre o comportamento de ovinos em pastagem de azevém perene adensado. Esses autores obtiveram taxas de 48 bocados/minuto e tempo de pastejo 545 minutos/dia, corroborando a afirmativa de Hodgson (1990) de que, em Tabela 6 -Atividades pontuais e taxa de bocado no segundo dia de pastejo de ovinos em Panicum maximum cv.…”

Production parameters and forage loss of oat and rye grass pastures managed with beef heifers fed diets with energy supplementation

“…When grazing is managed with daily supply from 10 to 12 kg of DM/ 100 kg of LW, the maximum animal performance can be demonstrated (Hodgson, 1990), so heifers of all treatments had the opportunity to show their maximum potential of individual performance due to the supplies and per area, because the forage mass to which they were subjected was 1245.02 kg DM/ha (Table 3) on average. Regarding the supply of leaf blades, in which, according to Forbes & Hodgson (1985), of the components of the forage, leaf fraction is the one which presents the best quality and represents more than 80% of the diet, there was no difference between treatments (P>0.05) ( Table 4).…”

Effect of different grazing pressures by lambs grazing <i>Lolium perenne</i> and <i>Dactylis glomerata</i> pastures during spring on: 2. Intake and growth

“…In particular changes in sward structure (height, leafiness, density and distribution) affect intake due to their effect on the rate of intake and selective grazing (Allden & Whittaker, 1970;Chacon et al 1978). Forbes & Hodgson (1985) pointed out that as grazing time increases and the amount of feed decreases, there is a decline in DM intake per bite and a tendency to increase the time spent grazing. However, there is a limit to what extent animals can compensate for reduced intakes per bite (Hodgson & Illius, 1996).…”