1. Milk-substitute diets, in which 330-360 0.) or 610-700 (H) g/kg milk protein was replaced by protein from a thermo-alkali-treated soya-bean flour (SF) or from fish-protein concentrate (FPC), were compared in an experiment involving fifty Friesian calves, of which half were supplemented with a growth promoter, Grofas, known to have bacteriostatic properties. The liquid diets were fed ad lib. from 48 h of age until 136 kg live weight.2. Seven calves, given non-milk protein, died or were removed from the experiment. There was little difference between treatments in the incidence of diarrhoea or in other observations on health of surviving calves, but those given non-milk protein maintained a lower mean rectal temperature. 3. Weight gain was reduced, especially during the first 3 weeks of life, by inclusion of non-milk protein. The reduction was greater for SF than for FPC, and greater at the H level. Supplementation with Grofas improved weight gain for calves given non-milk protein, but tended to reduce that for calves given milk protein.4. Apparent digestibility of dry matter and protein was reduced when non-milk protein was used. The reduction was greatest at a young age, greater for SF than for FPC and greater at the H level. Apparent digestibility of fat was most markedly reduced with FPC, especially at 1 week of age, and was increased by Grofas supplementation. Digestibility of the carbohydrate in SF was low at 1 week but increased with age. Grofas supplementation caused a marked reduction in the disappearance of SF-carbohydrate in the alimentary tract. Apparent absorption of ash and calcium were reduced by non-milk protein, especially by FPC. The reduction in absorption of ash from SF was moderated by Grofas supplementation. Although Ca retention for calves given SF at the H level was very low, no bone defects were observed. 5. Nitrogen retention was slightly lower for calves given non-milk protein, but the efficiency of retention of apparently digested N was greater for calves given non-milk protein because of the much reduced urinary N excretion associated with a lower apparently digested N intake.6. Dressed-carcass weight and 'killing out' percentage were lower for calves given non-milk protein, especially SF at the H level. Adrenal weights were markedly increased by feeding SF especially at the H level.Pancreas weight was greater for calves given SF than for those given FPC.7. Weight of abomasal contents at slaughter was much lower for calves given non-milk protein. Weight of intestinal tissue and of total tissue in the alimentary tract were markedly increased by non-milk protein, especially by SF at the H level, and reduced by Grofas supplementation. The increased weight was associated with increased thickening of the walls of both the small and large intestine, which was possibly associated with hypertrophy of muscle cells.8. It is concluded that up to 360 g/kg milk protein could be replaced by protein from this thermo-alkalitreated SF, and up to 610g/kg milk protein from this FPC without markedly a...

I. Eighty bull calves, comprising forty-eight Ayrshire and sixteen each of the Friesian and Jersey breeds, were used in a randomized block experiment. Forty calves were maintained at a mean environmental temperature of 21' and forty at 1 4 . 5 ' . Within each temperature, twenty calves were reared from birth on a liquid milk substitute diet (pre-ruminant calves) and twenty were weaned at 35 d of age on to dry food (ruminant calves). Each type of diet was given either ad lib. or at a restricted level. The calves were slaughtered at about xoo d of age.2. The incidence of a high rectal temperature ( > 39.33') was greater for the pre-ruminant than for the ruminant calves during the first 14 d of life and throughout the whole experimental period, and was higher for calves at an environmental temperature of 21' than for those kept at 14.5'. During the experimental period as a whole, but not during the first 14 d of life, the incidence of diarrhoea was greater for the pre-ruminant calves. Mean rectal temperature was higher for the pre-ruminant calves and also higher for the calves reared at the high environmental temperature.3. The incidence of lung lesions at slaughter was significantly higher in the ruminant than in the pre-ruminant calves, and tended to be higher at the high environmental temperature. There was a highly significant positive relationship between severity of lung lesions and incidence of a high rectal temperature (> 39.33') and mean rectal temperature. Jersey and Friesian calves, but not Ayrshire calves, showed increased severity of lung lesions with increasing relative humidity at the low environmental temperature. When the results at the 'high' environmental temperature were combined with those obtained in an earlier experiment, the severity of lung lesiogs for Jersey and Friesian calves increased with decreasing relative humidity. At the 'high' but not at the 'low' temperature, severity of lung lesions was inversely related to skin ~eight/kgO.'~.4. Live-weight gain was much lower for the ruminant calves, but was unaffected by environmental temperature. Daily dry-matter intake from liquid diets given ad lib. did not differ between breeds at the same live weight. In contrast, daily dry-matter intake from dry food given ad lib. was greatest for the Jersey and lowest for the Friesian at the same live weight. The same daily dry-matter intake from liquid as from dry diets was achieved at similar percentages of mature weight for the three breeds. Relative weight gain within type of diet was similar for Jersey and Ayrshire calves, but tended to be higher for the Friesian calves.5 . Carcassweight, carcass eight^.'^, perirenal fat deposition, skin weight and killing out percentage were much lower for the ruminant calves. When adjusted for differences between treatment means for carcass weigh@.'*, perirenal fat deposition was greater at the ad lib. levels of intake and was 36% greater for pre-ruminant calves given milk substitute ad lib. at an environmental temperature of 2 1 ' than for those maintained at 14...

353The nutrition of the veal calf reared from birth to a slaughter weight equivalent to 22 % of mature cow weight of the breed.2. All the calves were given a milk substitute diet ad lib. in two feeds daily. Six of the calves received this diet alone and the remaining twelve calves were offered roughage ad lib. from I week of age, either as meadow hay or as barley straw. The calf-house was maintained at a mean temperature of 23' and a mean relative humidity of 62 %.3. The mean total intake of meadow hay and barley straw over the experimental period of about 12 weeks was 3.0 kg and 0.4 kg respectively. Only three calves were consuming any meadow hay and only two calves any barley straw at 7 weeks of age.4. The roughage consumed had no effect on the incidence of diarrhoea, on dry-matter intake from milk or on live-weight gain. All the calves offered meadow hay had lung lesions at slaughter. Severity of lung lesions in the Jersey and Friesian calves combined, but not in the Ayrshires, tended to be inversely related to the relative humidity to which they were exposed.5 . Dressed carcass weight and killing out percentage tended to be lower for the calves offered meadow hay. There was a highly significant inverse relationship between total intake of hay and killing out percentage. Perirenal fat depositionin relation to carcass weight was significantly lower and carotenoid content of the fat significantly higher for the calves offered the meadow hay. Skin weight per unit of slaughter weight 0.78 or carcass weight OJ* was significantly greater for the calves given the milk substitute diet only. .It is concluded that the calf shows very little desire to eat roughage when given a goodquality milk substitute diet ad lib. and that, even when the amounts of roughage consumed are small, this has a deleterious effect on carcass quality.The Brambell Committee (Brambell, 1965) recommended that calves restricted to liquid diets for the production of veal should be offered palatable roughage from I week of age, so that their supposedly innate desire to ruminate should not be frustrated. Since, in veal production, dry food is usually withheld, an experiment was made to find the effect of offering roughage, in the form of either good-quality meadow hay or barley straw, on the performance and carcass quality of calves given a milk substitute diet ad lib.

The effect of a gradual increase in dry-matter concentration from 140 g/kg (LD diets) to a maximum of 215 g/kg (HD diets), and the effect of an increase in fat concentration from 225 g/kg D.M. and reduction in protein concentration from 298 g/kg D.M. (LF diets) to 254 g fat and 211 g protein/kg D.M. respectively (HF diets) was examined with 32 Friesian bull calves in a 2 x 2 factorial experiment. Milk substitutes were offered ad libitum in two feeds daily from 2 days of age. The dietary changes were first introduced at 7 weeks of age and differences became progressively greater as further changes were made at 9, 11 and 13 weeks. The calves were slaughtered at 16 weeks of age.Dry-matter intake for calves given the HD diets increased faster with age after 7 weeks than that for calves given the LD diets. For the period 7-16 weeks, calves given the HD diets consumed 17 % more D.M. than those given the LD diets and had a 13 % greater rate of live-weight gain (1-57 v. 1-39 kg/day), although most of the increase in weight gain occurred between 9 and 13 weeks of age.There was no significant effect on D.M. intake or on live-weight gain of altering the fat and protein concentrations in the milk substitute, although feed conversion ratio (kg D.M. intake/kg weight gain) was higher for the HF than for the LF diets. Apparent digestibility of D.M., crude protein and fat were reduced with the HF diets, but the efficiency of retention of the digested nitrogen was improved.During the second and third weeks of life, D.M. intake reached a peak at approximately 67 g/kg 0 ' 75 and subsequently declined to stabilize at about 56 g/kg 0 " 78 . However, a gradual increase in concentration of the milk substitute from 140 to 215 g D.M./ kg increased intake to about 62 g D.M./kg 075 . The results clearly indicate that, at a dietary concentration of 140 g D.M./kg, maximum D.M. intake cannot be achieved because the volume of fluid that needs to be ingested exceeds the capacity of the digestive system. In contrast, at reconstitution rates increasing from 140 to 215 g D.M./ kg, distension of the stomach becomes less important and physiological and metabolic factors seem to assume a greater role in the control of feed intake.

SUMMARY1. Fifty-one Jersey, Ayrshire and British Friesian male calves were reared from birth to veal weights on one of three liquid diets.2. Two ultra-high fat milk powders containing 680 g fat, either beef tallow (T) or a mixture of coconut oil and beef tallow (CT)/kg dry matter were prepared and mixed with liquid skim milk (35 g powder/kg) to give diets TLS and CTLS, containing 200 g fat/kg dry matter. A third diet consisted of reconstituted spray-dried skim milk powder containing 200 g margarine fat/kg (MDS).3. The incidence of diarrhoea and of nasal discharge for all breeds, and of a high rectal temperature for the Ayrshire breed was greatest for calves given diet MDS and lowest for those given diet TLS. The incidence of lung lesions at slaughter was 100, 72 and 57% for the Jersey, Friesian and Ayrshire breeds respectively. Severity of lung lesions was lowest for calves given diet TLS.4. Dry-matter intake and live-weight gain, especially for the Ayrshire breed, were greater for calves given diets containing liquid skim milk and the ultra-high fat powders (TLS and CTLS).5. Fat digestibility was lowest on diet TLS. Protein digestibility increased with age. Digestibility of dry matter and lactose, and absorption of ash and calcium decreased with age. Calcium and N retention were lowest on diet MDS.6. Killing-out percentage was highest for the Friesian and lowest for the Jersey breed. Perirenal fat deposition was highest for the Jersey and lowest for the Ayrshire breed. Skin weight/kg0·73 was higher for the Ayrshire calves than for the other two breeds.