A patch choice experiment was conducted in which sheep were offered choices between patches of upland pasture which differed in their sward height and degree of shelter from the wind. Experimental plots (48 m ✕ 4 m) were divided into 4 m ✕ 4 m patches. Alternate patches were mown in advance of the experiment to create nominal sward heights of 4 and 6 cm. Portable shelters were erected on the windward side of alternate patches to reduce wind speed on sheltered patches by half. The four treatment combinations used to test the influence of sward height, shelter and their interaction on patch use were: patchy swards with and without shelters and uniform swards with and without shelters. Five adult sheep per treatment were observed while grazing the plots for 6 h/day on five occasions (days) in autumn. Patch choice was measured by video observation and using a patch marker technique. On none of the observation days was the weather condition sufficiently severe that animals were outside their thermoneutral zone. There was a strong influence of sward height on patch use with sheep spending 0·382 of their time on short swards when patchy swards were offered compared with 0·503 of their time on equivalent areas when swards were uniform. Thermal conditions did not influence patch choice with sheep spending an average of 0·442 of their time on equivalent patches whether they were sheltered or not. There was no interaction between sward conditions and thermal conditions on the amount of time spent on different patches. Data from the patch marker method supported observation data. The results confirm that sheep are resilient to extremes of cold weather commonly occurring at temperate latitudes and suggest that thermal constraints have minimal influence on the small-scale foraging movements of sheep, as long as they remain within their thermoneutral zone.

The aim of this study was to investigate the impact of a protein-free diet or diets differing in protein level on the morphology and enzyme activities of the small intestinal mucosa of the pre-ruminant calf.

Diets contained 14, 104, 205 and 279 g crude protein (CP) per kg dry matter (DM) supplied by skimmed-milk powder (SMP) and cream. Holstein male calves (no. = 6) aged 6 weeks (65 to 75 kg) were fitted with an abomasal catheter and simple T-piece cannulae in the duodenum, jejunum and ileum. The milk replacers were continuously infused into the abomasum. Each calf tested the four diets randomly during four experimental periods. Biopsies of intestinal mucosa were collected at each intestinal site through the cannulae and were used for morphology measurements (villus and crypt area, height and width) and the determination of the activities of dipeptidyl-peptidase IV, amino-peptidases A and N, lactase and alkaline phosphatase.

When the dietary CP level increased from 14 to 205 g/kg DM, villus height quadratically increased by proportionately 0·35 (P < 0·05) and crypt width linearly increased by proportionately 0·25 (P < 0·01) at the jejunum. This effect was associated with linear increases in the activities of dipeptidyl-peptidase IV and lactase and a quadratic increase in the activity of alkaline phosphatase.

To conclude, feeding a protein-free diet impacted negatively on the morphology and hydrolytic activity of the calf’s small intestine. These observations may partly explain the fact that endogenous protein losses measured with such a diet are often lower than in physiological conditions.

Two groups of grazing lactating dairy cows (no. = 10) were offered straw/sugar-beet pulp mixtures of different straw and sugar-beet pulp content. The low straw mixture (LS) contained 310, 592, 65, 9 and 24 g/kg dry matter (DM) of barley straw, sugar-beet pulp, cane molasses, urea and minerals respectively. The high straw mixture (HS) contained 540, 359, 65, 12 and 24 g/kg DM of these ingredients. This resulted in metabolizable energy and DM degradability values of 10·4 and 8·4 MJ/kg DM and 0·48 and 0·42 for mixture LS and HS, respectively. In experiment 1, the mixtures were offered for 1 h after each milking while in experiment 2 the amount of LS available was restricted to the intake of the HS mixture. The animals continuously grazed a perennial ryegrass sward with sward height maintained at 7·5 and 6·9 cm respectively for experiment 1 and 2. Forage intakes in both experiments were measured using the n-alkane technique. In experiment 1, intakes of the forage supplement were 5·3 and 2·3 kg DM per day (s.e.d. = 0·51, P < 0·001), while herbage intake was 11·5 and 14·5 kg DM per day (s.e.d. = 0·77, P = 0·004), resulting in total forage intakes of 16·9 and 16·7 kg DM per day for treatments LS and HS respectively. No significant differences in terms of time spent grazing, ruminating and eating forage supplement were observed. No significant differences in terms of animal performance were observed. In experiment 2 intakes of the forage supplements were 2·8 kg DM per day for both treatments while herbage intake was 13·0 and 13·2 kg DM per day (s.e.d. = 110) resulting in total daily intakes of 15·8 and 16·0 kg DM (s.e.d. = 1·24) for treatment LS and HS, respectively. No significant differences in terms of grazing time, rumination time or animal performance were detected. It was concluded that under conditions when herbage was readily available, higher amounts of high energy/high degradability forage supplement were consumed than of low energy low degradability forage supplements. However, total dry matter intakes were equal. Intake from forage supplements seem to be affected by short-term fill effects in this situation.