The effect of daily herbage allowance and sward characteristics upon the ingestive behaviour and herbage intake of calves under strip‐grazing management

Abstract

Measurements of herbage intake and ingestive behaviour were made on British Friesian calves 4-9 months old, which were strip-grazed on swards of S24 perennial ryegrass at three (Experiment A) or four (Experiment B) levels of daily herbage allowance in three (A) or four (B) 12-d periods. Herbage intake declined by approx. 18% as daily herbage allowance was reduced from 90 to 30 g DM per kg LW in both experiments, but the relationship between intake and allowance was not consistent between periods.Bite size and rate of biting were greater in calves on low than on high allowances after entry to a new strip of herbage but the positions were reversed towards the end of grazing. Reduced herbage intakes at low allowance resulted from reductions of approx. equal magnitude in bite size, rate of biting and grazing time, though not all of these effects were significant. It is suggested that these responses result from the increasing difficulty of prehending and ingesting herbage as swards are grazed down. The calves at low herbage allowances did not increase grazing time, probably because their behaviour was conditioned by anticipation ofa new allowance of herbage.Bite size and daily herbage intake were greater on a spring sward than on an autumn sward, but within experiments herbage intake was not consistently related to any of the sward characteristics measured.

Comportamento ingestivo e consumo de forragem por cordeiras em pastagem de milheto recebendo ou não suplemento

“…Foram empregados avaliadores treinados, cada um responsável pela observação de quatro animais-teste. As anotações foram feitas a cada dez minutos, por meio de observação visual (Jamieson & Hodgson, 1979), com registro das atividades de pastejo, ruminação, ócio e taxa de bocados (tempo para realizar 20 bocados), conforme metodologia descrita por Hodgson (1982). O tempo gasto pelos animais na seleção e apreensão da forragem, incluindo os curtos espaços de tempo utilizados no deslocamento para a seleção da dieta, foi considerado tempo de pastejo (minutos/dia) (Hancock, 1953).…”

“…No cálculo da massa de bocado, dividiu-se o consumo diário de pasto, expresso em g/dia/animal, pelo total de bocados (taxa de bocado × tempo de pastejo; Jamieson & Hodgson, 1979). A massa de bocado foi obtida da seguinte forma: Ingestão de MS de pasto/dia, dividida pelo tempo de pastejo dos animais.…”

Comportamento ingestivo de novilhas de corte submetidas a estratégias de suplementação em pastagens de aveia e azevém

“…As temperaturas médias nestas datas foram de 18,3; 16,4 e 9,5 o C. Foram utilizados oito avaliadores, que revezaram em plantões de 4 horas, ficando um observador responsável pela observação dos animais-teste de dois piquetes. As anotações foram feitas a cada dez minutos, por meio de observação visual (Jamieson & Hodgson, 1979a), para registro das atividades de pastejo, ruminação, ócio e permanência no cocho. O tempo gasto pelos animais na seleção e apreensão da forragem, incluindo os curtos espaços de tempo utilizados no deslocamento para a seleção da dieta, foi considerado tempo de pastejo (TP) (Hancock, 1953).…”

Evaluation of the feeding value of Aries HD perennial ryegrass(Lolium perenne).I. Performance of lactating ewes in spring

“…Two 24-h profiles were completed, each spread over four 6-h periods (0600-1200, 1200-1800, 1800-2400, 2400-0600 h), coinciding with faecal sampling. Observations were recorded every 10 minutes for the number of ewes grazing in each plot (Jamieson & Hodgson 1979). During darkness an infrared nightscope was used to aid in the identification of grazing activity.…”

“…Total time spent grazing was calculated by adding together observations for the four periods. Bite rates (time taken for 20 bites) were recorded on random animals in each plot, between each set of grazing observations during daylight hours (Jamieson & Hodgson 1979). Bite weight (g OM bite ') was calculated using measured values for herbage intake (g OM day 1 ), grazing time (min per 24 h), and bite rate (bites per min) as described by Kusmartono et al (1996).…”