Salmon oil (16·5 kg /t), a source of long-chain polyunsaturated n-3 fatty acids, was included in diets offered to multiparous sows during pregnancy and lactation to measure responses in pre-weaning mortality and performance of piglets in two studies. The first study, carried out under commercial conditions, included 196 sows which were offered salmon oil and control diets from immediately post service until weaning. The same diets were also offered to 10 sows per treatment from day 58 of pregnancy in a controlled nutritional study which measured the effects of salmon oil on piglet tissue fatty acid composition. Offering salmon oil to the sow significantly increased gestation length and decreased individual piglet birth weight but had no effect on litter size at birth. Overall, salmon oil reduced pre-weaning mortality from 11·7% to 10·2% mainly by reducing the incidence of deaths from crushing by the sow. More detailed analysis of mortality using a general linear mixed model and 2294 piglet records, demonstrated that the incidence of pre-weaning mortality was significantly decreased with increasing individual piglet birth weight and by inclusion of salmon oil in the diet; the incidence of mortality increased with average piglet birth weight in a litter. Salmon oil inclusion had no effect on weight of litter weaned, sow lactation food intake or subsequent reproductive performance. In both studies, dietary salmon oil increased the proportions of long-chain n-3 polyunsaturated fatty acids in colostrum to a similar extent. In the nutritional study, inclusion of salmon oil reduced the proportions of 20: 4 n-6 in piglet liver and brain at birth and increased the proportions of long-chain n-3 polyunsaturated fatty acids. Therefore, despite reducing piglet birth weight, offering sows salmon oil reduced pre-weaning mortality of piglets. The nutritional study showed that the amount and type of marine oil used may not have been optimal.

A series of laboratory and animal studies examined the use of chemical and biological agents to enhance the digestibility of Rhodes grass (grass) cut at 60 (young) and 100 (mature) days of regrowth and ensiled as big round bales. The treatments included an untreated control (C), a microbial inoculant (I), NaOH, CaO and NaOH plus inoculant (NaOH + I). Inoculant was grown anaerobically, using a starter culture of rumen fluid from cattle given Rhodes grass. Treatments C, I, NaOH, NaOH + I, were offered separately to twelve dairy heifers, in a 3 ✕ 4 randomized complete block design, repeated twice for each grass silage. C and I had substantial mould growth, compared with no visible mould in NaOH or NaOH + I. CaO treatment was effective in preventing mould growth, but had little effect on the chemical composition and in sacco digestibility of mature grass silage. NaOH reduced NDF content and increased in sacco digestibility (P < 0·05) but not the in vivo digestibility (P > 0·05) of both mature- and young-grass silage. The effects of other treatments on nutritive value were non-significant at both stages of maturity. NaOH increased the intake of mature-grass silage by 24-26% (P < 0·05), but had little effect on the intake of young-grass silage (P > 0·05). Treatment I consistently reduced grass silage intake (P < 0·05) for young-grass silage. The findings of these studies show that treating mature Rhodes grass with NaOH will improve its nutritive value and reduce mould growth in conserved herbage. However none of the treatments in this study had any consistently positive effects on the in vivo nutritive value or storage quality of young-grass silage.

In each of 2 years (years A and B), the effects of three nutritional regimes were examined using 12 cows kept at pasture for 77 days at 2000 m above sea level. Two supplement formulations (1 and 2) were designed, both equally high in readily fermentable energy (14·6 MJ metabolizable energy (ME) per kg dry matter (DM)) but differing in crude protein content (53 and 193 g/kg DM). The treatments imposed were either pasture grass alone (control groups; both seasons) or grass and supplements provided at three levels relative to energy (E) and protein (P) maintenance requirements estimated for lowland conditions. These levels were (i) 1·0 E: 0·8 P provided by 4·6 kg of supplement 1 per day in both years; (ii) 0·5 E: 0·4 P provided by 2·2 kg of supplement 1 per day in year A; (iii) 1·0 E: 2·5 P provided by 4·4 kg of supplement 2 per day in year B. Intensive measurement periods, including food intake estimation by the double alkane technique, were carried out in weeks 3, 7 and 11 on Alpine pasture. Performance data, plasma levels of indicative blood traits and body condition were additionally monitored in the cows at a lowland site for 2 weeks prior to transport. Supplementing with a high energy/low protein concentrate gave no clear benefit in milk yield, which declined proportionately by 0·33 in the 11 weeks under Alpine conditions. Provision of additional supplementary protein (supplement 2) resulted in a proportionate decline in milk yield of only 0·20 over the 11-week period. Cows exhibited high substitution ratios of 1·4 to 2·6 kg herbage DM per kg concentrate DM and cows on all treatments were estimated to consume similar amounts of ME. A combination of reduced fibre intake and lower fibre digestibility with supplementation significantly reduced milk fat contents to low levels. Energy supplementation significantly reduced plasma β-hydroxybutyrate levels. However, live-weight and body tissue loss rates (based on ultrasonic scans of subcutaneous fat layer and longissimus dorsi muscle) were equally great with and without energy supplementation but less severe with extra protein (supplement 2). Adaptation to the high Alpine conditions was achieved in all treatments as indicated by increased blood haemoglobin, accompanied by a lower plasma level of insulin-like growth factor-I. Plasma thyroid hormone levels suggested that adaptation to energy deficiency and possibly to cold was more effective with supplementary energy. Other energy-dependent blood metabolites and insulin responded similarly in all treatments to high altitude grazing. Estimated maintenance energy requirement for Alpine conditions was 0·72 times greater than lowland maintenance requirement.

Seasonal milk production systems rely on heavy inputs of nitrogenous fertilizer, which typically generate pastures with a high crude protein (CP) and low fermentable energy concentration. High intake of CP, particularly in association with low rumen fermentable energy, increases systemic ammonia and urea and has been associated with reduced fertility in cattle. The objective of this study was to examine the relationship between pasture protein intake and fermentable energy supplementation on a range of blood metabolites and on embryo survival and development in cattle.

Oestrous synchronized, nulliparous beef heifers (no. = 175) were randomly assigned to one of four pasture-based dietary treatments in a 2 ✕ 2 factorial study carried out over 2 years. Animals were randomly allocated to either high (85 kg nitrogen (N) per ha; HN) or low (0·0 kg N per ha; LN) N fertilized pastures and within pasture treatment were randomly allocated to receive either zero or three (+3P) kg dry matter (DM) of molassed sugar-beet pulp (MSBP) per head per day as follows: (1) HN (no. = 44), (2) HN + 3P, (no. = 43), (3) LN (no. = 44), (4) LN + 3P (no. = 44). Blood samples were collected to measure systemic concentrations of ammonia, urea, insulin, glucose and progesterone. Heifers were artificially inseminated (AI) and pregnancy diagnosis was carried out by ultrasonography 30 days after AI. Subgroups of pregnant animals across treatments were slaughtered 40 days after AI to estimate conceptus development.

The HN pasture had a higher CP (P < 0·001) and lower water-soluble carbohydrate (P < 0·01) concentration. Plasma concentrations of ammonia (P < 0·05) and urea (P < 0·001) were higher in the animals on the HN pastures and were reduced (P < 0·05) by MSBP supplementation, but only in animals on the HN pastures. Embryo survival rate across treatments was high overall (71%) and not related to pasture CP concentration, fermentable energy supplementation or systemic concentrations of ammonia, urea, glucose or insulin. There was no relationship between dietary treatment or systemic metabolites and any of the estimates of conceptus development. Systemic insulin was not affected by pasture N treatment or MSBP supplementation (P > 0·05). Systemic concentrations of glucose were not affected by pasture N treatment (P > 0·05) but were increased by MSBP supplementation (P < 0·05). Systemic progesterone was not affected by pasture CP or MSBP supplementation (P > 0·05) but at day 7 after AI was positively related (P < 0·05) to embryo survival. Intake of high CP herbage elevated systemic ammonia and urea but there was no association with embryo survival rate or embryo development in heifers.

The effects of space allowance during transportation and duration of a mid-journey lairage period on measurements of stress, injury, dehydration, food restriction and rest in young calves were assessed during and after transport. Groups of calves were transported for two 9-h journeys (at a space allowance of either 0·375 or 0·475 m2 per calf) separated by a mid-journey lairage period of either 1 or 12 h. Non-transported calves were offered milk replacer and drinking water either at the usual times or only at the same times as the transported calves.

During transport, transported calves spent significantly less time lying down and had a greater plasma cortisol concentration than control calves. Under the driving conditions used, increased space allowance was not associated with greater injury or loss of stability. The duration of the mid-journey lairage was not an important factor; the shorter lairage time, giving the calves sufficient time to receive milk replacer but little opportunity to rest, had no major detrimental effects on the variables used to assess welfare. Although there was little evidence that transport affected immunological variables, there was some evidence that it adversely affected the health of the calves post transport.

Two trials were conducted to study the effect of the stage of maturity of fresh herbage on its digestibility by two breeds of sheep (Churra v. Merino). The sward consisted of a mixture of grasses and clover, and was harvested either in late May (early cut, EC) or in late July (late cut, LC). In each trial, 12 mature sheep of each breed were used. Each animal received a different amount of fresh herbage, so that levels of food intake ranged between 8·1 and 24·7 g dry matter (DM) per kg body weight per day. EC herbage showed higher crude protein content (116 v. 67 g/kg DM), lower neutral-detergent fibre concentration (494 v. 664 g/kg DM) and higher DM digestibility (0·687 (s.e. 0·005) v. 0·463 (s.e. 0·007)) than the LC herbage. DM digestibility coefficients observed in Churra (0·694 (s.e. 0·028) for EC and 0·476 (s.e.0·028) for LC herbage) tended to be greater than those observed in Merino sheep (0·680 (s.e. 0·021) for EC and 0·452 (s.e. 0·040) for LC herbage). With the EC herbage DM digestibility tended to decrease as the level of intake increased. Samples of dried herbage were incubated in the rumen of Churra and Merino sheep to determine the DM degradability by the in situ technique. Fractional degradation rates (c values) were significantly faster in the rumen of Churra than in Merino (0·046 (s.e. 0·003) v. 0·031 (s.e. 0·002)), with large differences between breeds in the DM disappearance rates at intermediate incubation times, and no significant differences between Churra and Merino sheep in the mean a + b values. Microbial N supply, calculated from the urinary excretion of purine derivatives, was significantly affected by the herbage maturity stage and by the level of DM intake, but not by the breed of sheep. It is suggested that differences between breeds of sheep in food digestibility may be related to their ability to digest fibrous diets.

The effects of trace element deficiencies in lambs, particularly zinc, copper, cobalt and selenium, include decreased growth rates and increased mortality. However, trace element supplementation of sheep reared under extensive conditions has several logistical problems.

Two trials were designed to investigate the effect of a zinc, cobalt and selenium soluble glass bolus on the trace element status of out-wintered ewe lambs. In trial 1 600 8-month-old ewe lambs (500 Scottish Blackface and 100 North Country Cheviots) were allocated to two treatment groups; 300 were treated with a zinc, cobalt and selenium soluble glass bolus (zinc) and 300 were untreated (control). In trial 2, 315 8-month-old Scottish Blackface ewe lambs were allocated to three treatments: 105 were treated with the zinc, cobalt and selenium soluble glass bolus (zinc), 105 were treated with a copper, cobalt and selenium soluble glass bolus (copper) and the remaining 105 were untreated (control). Blood samples were collected immediately prior to giving boluses and again after approximately 4 months. These were assessed for zinc (plasma zinc concentration), cobalt (serum vitamin B12 concentration), selenium (erythrocyte glutathione peroxidase activity) and copper status (plasma copper concentration, caeruloplasmin, amine oxidase and superoxide dismutase activity and calculation of the ratio between the caeruloplasmin and plasma copper).

The zinc bolus in both trials significantly increased the plasma zinc concentrations (P < 0·001 and P < 0·01 respectively), erythrocyte glutathione peroxidase activities (P < 0·001) and serum vitamin B12 concentrations (P < 0·001). The copper bolus also significantly increased the erythrocyte glutathione peroxidase activities (P < 0·001) and serum vitamin B12 concentrations (P < 0·001) when compared with the controls but were not significantly different from the zinc group. The copper bolus significantly increased all of the copper status indicators (P < 0·01) when compared with the control and zinc groups. However, in trial 1 when only the zinc and control groups were compared, the zinc bolus significantly increased the ratio (P < 0·001) and serum caeruloplasmin (P < 0·001) and erythrocyte superoxide dismutase (P < 0·01) activities. These responses were not observed in trial 2 with the erythrocyte superoxide dismutase being significantly reduced in the zinc group when compared with the control group (P < 0·001).

The zinc, cobalt and selenium soluble glass bolus increased the status of all three trace elements consistently for a period of at least 100 days. The increases of cobalt and selenium status were similar to those achieved using the copper, cobalt and selenium bolus, which also increased the copper status of the sheep.

Eight mid-lactation Holstein-Friesian dairy cows were used in an experiment to investigate whether poor transfer to milk of (n-3) long chain (≥C20) poly-unsaturated fatty acids (n-3 LCPUFA), from diets containing fish oil, is related to their mode of transport in plasma lipoproteins. The cows were split into two groups of four, each of which was housed with 24 other cows which did not provide blood data in this experiment. All cows received a basal diet ad libitum consisting of (kg/t dry matter) silage (539), grain distillers’ grains (148), rolled barley (248) and soya (65). All cows also received a mid-day meal of 2·76 kg per cow per day of molassed sugar-beet shreds. The control group (C) received no oil supplement but those in the treatment group (F) received 300 g per cow per day of fish oil absorbed onto the sugar-beet shreds. Fish oil inclusion progressively depressed milk fat concentration of the four cows from each group over the 3 weeks of the experiment so that levels were approximately 20 g/kg lower for cows in treatment F than for those in C (P < 0·05). Mean concentrations over all cows of the long-chain (≥C20, n-3) poly-unsaturated fatty acids in milk fat (g/100 g) were 0·12 and 0·54 for treatments C and F respectively, whilst corresponding output in milk (g/day) increased from 116 to 3·91, an average efficiency of transfer of 4·6%. The fatty acid compositions of the lipoproteins were measured in plasma samples from the four cows from each group after 3 weeks on the experimental diets The proportions (g/100 g fatty acids) of C20: 5 (n-3) in cholesteryl (CE) and phospholipid (PL) of high-density lipoprotein (HDL) in the plasma were respectively increased from 0·97 to 4·39 (P < 0·05) and from 1·15 to 4·74 (P < 0·01) by the fish-oil supplementation. For C22: 6 (n-3), the proportions in CE and PL of HDL respectively increased (P < 0·001) from 0·02 to 0·23 and from 0·16 to 2·18 as a result of the supplementation. The mean proportions (g/100 g fatty acids) of C20: 5 (n-3) and C22: 6 (n-3) in the triglyceride fraction of very low-density lipoprotein were 1·05 and 2·3 respectively and were not significantly altered by fish-oil supplementation (P > 0·05). It is suggested that the low transfer efficiency of (n-3) LCPUFA to the milk is partly due to their transport in the plasma largely as components of HDL lipids which are unavailable to the mammary gland.

In order to establish the response of dairy cow performance to concentrate supplementation in contrasting grazing conditions and for cows differing in milk yield at turn-out, three experiments were conducted. Each year, two levels of herbage allowance were studied in interaction with four (experiment 1) or three (experiments 2 and 3) levels of concentrate on two groups of 30 to 40 mid-lactation Holstein cows producing between 20 and 46 kg milk at turnout. Amount of concentrate and herbage allowance ranged from 0 to 6 kg fresh weight and from 12 to 22 kg dry matter (DM) per cow per day respectively. The supplementation led to average responses, per kg DM concentrate, of 104 kg milk, +66 g/day body-weight gain, +0·19 g/kg milk protein and -0·57 g/kg milk fat. These responses remained linear up to 4 or 6 kg according to the years and treatments. The response to the concentrate did not vary with the milk yield or composition at turn-out. The increase in the herbage allowance from 12 to 16 kg DM per cow per day (experiment 1) improved milk yield (+1·2 kg/day) and milk protein (+0·7 g/kg) while the increase from 16 to 22 kg DM (experiments 2 and 3) had less effect (+0·5 kg/day milk yield and +0·4 g/kg milk protein). There was no clear interaction between concentrate supplementation and herbage allowance. Under the usual conditions of spring pasture, with cows in mid lactation, the use of a constant level of concentrate at grazing proves to be a technique of some interest.

Two experiments were conducted in which growing sheep were given choices between foods differing in their contents of urea. The crude protein (CP) contents of both of the foods of the pair were also varied. The hypothesis tested was that the diets selected would be those that met the effective rumen degradable protein (eRDP) requirements of the animals and would avoid excess consumption of eRDP. Three basal foods, differing in CP were formulated. D was designed to be deficient in CP with 80 g CP and 58 g eRDP per kg DM; H was calculated to be adequate with 159 g CP and 114 g eRDP per kg DM; P had excess with 210 g CP and 148 g eRDP per kg DM. Other foods were made by adding 12·5 or 25 g urea per kg fresh matter to each of the three basal foods to make a further six foods. In both experiments Texel ✕ Greyface female sheep were used. In experiment 1, 34 sheep weighing 37·2 (s.d. 1·85) kg were randomly allocated to one of six groups and each group was offered a choice between a pair of foods. Groups 1 to 3 were offered pairs in the D series (D v. D + 12·5 g urea per kg (no. = 6), D v. D + 25 g urea per kg (no. = 6) and D + 12·5 g urea per kg v. D + 25 g urea per kg (no. = 5)). Groups 4 to 6 were offered the same pairs of foods but with H instead of D. In experiment 2, 96 sheep weighing 29·8 (s.d. 3·37) kg were randomly allocated to one of 12 groups. Groups 1 to 6 (no. = 6) were allocated a single food (D, D + 25 g, H, H + 25 g, P or P + 25 g urea per kg) throughout the experiment. Groups 7 to 12 were given a choice (no. = 10) between two foods. One food of the pair was the basal D, H or P. The other food was the same basal food supplemented with either 12·5 or 25 g urea per kg. On the single foods adding urea to D resulted in an increase in food intake and live-weight gain suggesting that D was deficient in eRDP. Adding urea to either H or P had no beneficial effects on intake or live-weight gain. This suggests that both contained sufficient eRDP in relation to energy. Across all choice treatments in both experiments there was a highly significant preference (P < 0·01) for the food with the higher urea content. In experiment 1 0·62 (s.e. 0·04) of the diet selected was the food with the higher urea content. In experiment 2 the figure was 0·64 (s.e.0·03). The general preference for the food with the higher urea content was unaffected by the CP contents of the foods used. The results do not support the hypothesis that sheep will avoid excess eRDP when given a choice and suggest that eRDP may not be a relevant dimension in diet selection in the conditions of these experiments.

Sixteen Holstein Friesian cows were offered ad libitum a forage mixture of three parts (dry-matter (DM) basis) maize silage (starch and neutral-detergent fibre (NDF) 324 and 395 g/kg DM) and one part grass silage (NDF 518 g/kg DM) in a 4 ✕ 4 Latin-square change-over design experiment using four periods each of 4 weeks. Cows were housed in a cubicle house, bedded on sand and given food through Calan gates. The four supplement treatments were control (no oil supplement, C); 1·5 kg/day processed crushed linseed (PL); 1·5 kg/day crushed linseed (L) and 0·6 kg/day marine algae (A) providing 0, 440, 423 and 109 g/day of oil respectively. Cows also received a pelleted concentrate in three equal meals (12·0, 10·5, 10·5 and 11·2 kg/day for C, PL, L and A respectively) containing (g/kg DM) 260, 203, 288 and 74 of crude protein, NDF, starch and water-soluble carbohydrate respectively. Oil supplementation depressed (P < 0·05) forage intake (11·2, 10·3, 10·1 and 10·1 kg DM per day) but milk yield was unaffected (P > 0·05) by treatment (mean 35·9 kg/day). Milk fat concentrations were low and further depressed (P < 0·05) by algal supplementation (33·5, 32·3, 32·3 and 25·6 g/kg). Algal supplementation caused a three-fold increase in the concentrations of (n-3) long chain (>C20) polyunsaturated fatty acids in milk fat (to 0·51 g/100 g fat) representing a transfer efficiency from diet to milk of ca. 5%. Oil supplementation increased levels of all trans monoenes in milk but the effect was much greater for treatment A (P < 0·05) and for trans-10 C18: 1 (1·52, 1·94, 1·72 and 6·12 g/100 g milk fat for C, PL, L and A respectively). Trans-10 C18: 1 was the predominant trans monoene in milk fat for all treatments (47·7, 45·2, 45·6 and 67·4% of total). Treatment A also caused the greatest increases (P < 0·05) in conjugated linoleic acid (CLA to 0·54, 0·69, 0·65 and 0·97 g/100 g milk fat). Although mainly cis-9, trans-11, a small proportion (4·8 to 5·5%) of the CLA was identified as the trans-10, cis-12 isomer for all treatments. This pattern of isomers of trans monoenes and CLA, which may have implications for the health properties of the milk, may be related to effects on rumen function caused by the high starch intakes (5·75, 5·09, 5·11 and 5·27 kg/day).

Sixteen Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 28-day experimental periods and a 4 ✕ 2 factorial arrangement of treatments to evaluate the effects of dietary nitrogen (N) source on dry-matter (DM) intake, diet digestibility, milk production, blood metabolite concentrations and N utilization. Experimental treatments consisted of two silages prepared from timothy and meadow fescue swards fertilized with either 52 or 104 kg N per ha (SL and SH, respectively) offered ad libitum supplemented with one of four concentrate supplements offered at 10 kg/day. A basal concentrate (control) was formulated from (g/kg on an air-dry basis) barley (307), oats (460), molassed sugar-beet pulp (200) and vitamins and minerals (33). Three isonitrogenous concentrates were prepared by replacement of basal concentrate ingredients (g/kg) with urea (14·4), wheat-gluten meal (WGM; 57·2) and heat-moisture treated mechanically expelled rapeseed cake (RSC; 188), respectively. Harvesting of secondary growths receiving higher applications of fertilizer N increased silage N content (19·2 and 23·6 g/kg DM, for SL and SH, respectively) but decreased water-soluble carbohydrate concentrations (respective values 149 and 93 g/kg DM). Increases in N fertilizer had no effect on silage DM intake, output of energy-corrected milk, milk fat or milk protein secretion, while provision of additional N in concentrate supplements improved all of these parameters. However, the magnitude of silage DM intake responses to additional N in concentrates was higher (P < 0·05) for SL than SH silage-based diets. Increases in dietary N content derived from silage or inclusion of urea, WGM or RSC in concentrate supplements led to a decline in the proportion of N intake secreted in milk. Relative to N derived from silage or urea, WGM and RSC supplements had beneficial effects on milk production. Both the quantity and quality of dietary N sources should be considered in future attempts to improve the efficiency of on-farm N utilization.

The live-weight gain (LWG) of young male red deer in New Zealand naturally slows during winter and feeding diets of mainly silage appears to exacerbate this effect. We aimed to quantify the effect of feeding silage on intake and LWG during winter and the ability to improve LWG by feeding supplements, mainly in the form of barley. Seven groups of eight deer were maintained outside in gravelled enclosures and offered silage ad libitum for 94 days during winter. Six groups were given supplements (950 g barley with 50 g rapeseed meal per kg to make all diets isonitrogenous) at rates of proportionately 0·2, 0·4, 0·5, 0·6, 0·7 and 0·9 of the metabolizable energy (ME) intake of the group given only silage (0). The study also examined the effect of the winter treatments on subsequent LWG to slaughter weight whilst grazing on pasture during spring and into summer (102 days).

Increasing supplement intake resulted in a decrease in silage dry matter (DM) and ME intake (P < 0·001) and an increase in total ME intake (P < 0·01). The substitution rate for silage DM was 0·84 (s.e. 0·079). LWG during silage feeding was positively related (P < 0·01) to supplement intake with an increase of 6·21 g/day per MJ per day. LWG on pasture was not related to either supplement feeding rate or LWG during winter. LWG over the entire experiment was related (P < 0·01) to supplement feeding rate, with a final difference in live weight of 6 kg between 0 and 0·9 groups.

This study has confirmed that the LWG of young male deer is low during winter when given only silage and that feeding supplements increases total ME intake and LWG. The reduced LWG due to silage feeding was not compensated for on pasture during spring and summer, thus delaying the time to reach slaughter weight by approximately 1 month. High proportions of silage in the diet appear unsuitable for young male deer if the aim is to achieve rapid LWG during winter.

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.