The nutrition of the veal calf

The nutrition of the veal calf 5. Comparison of two margarine fats

1. Twenty newborn Ayrshire male calves were used in a comparison of milk substitute diets containing two different margarine fats. The liquid diets were offered in two feeds daily ad libitum and the calves were slaughtered at 118 kg live weight.

2. The two diets consisted of reconstituted spray-dried skim milk powder containing 200 g margarine fat/kg. One fat contained coconut and palm oils (CP) and the other coconut, palm and groundnut oils (CPG). The essential fatty acid content of margarine CP was less than half that of margarine CPG.

3. The incidence of diarrhoea and of a high rectal temperature, and the severity of lung lesions tended to be higher, the incidence of nasal discharge was higher and daily dry-matter intake and liveweight gain were lower for calves given margarine CPG.

4. Digestibility and balance trials were made at 1, 4 and 10 weeks of age. Nitrogen balance and apparent digestibility of the fat and other nutrients were not affected by the source of margarine, but the digestibility of dry matter and of fat was highest at 4 weeks of age, and of protein was lowest at 1 week of age. Apparent absorption of ash and calcium declined with age and absolute calcium retention was highest at 4 weeks. Total plasma lipids at 13 weeks of age did not differ between treatments.

5. Age at slaughter was greater for calves given margarine CPG but dressed-carcass weight, killing-out percentage, perirenal fat deposition and kidney weight did not differ between treatments. Skin weight tended to be lower for the calves given margarine CPG. 6. It is suggested that the apparent increased susceptibility to infection of calves given margarine CPG was associated with its higher unsaturated fatty acid content.

The protein requirement of the ruminant calf. II. Further studies on the effect of protein content of the concentrate mixture on the performance of calves weaned at an early age

1. Eighty-four Friesian heifer calves were used in two experiments (Experiments 4 and 5) to study the protein requirement of the ruminant calf to 12 weeks of age. The calves were weaned at 5 weeks of age and given a concentrate containing one of several protein levels, together with hay and water.

2. In Experiment 4, the effect of changing the protein content of the concentrates at 8 weeks of age under ad libitum feeding conditions was studied. A concentrate containing 20·6% crude protein (air-dry basis) tended to promote more rapid weight gains in calves to 8 weeks than a similar concentrate with 12·1% crude protein. Following the change in diet at 8 weeks, both groups of calves given the low-protein diet gained weight at similar rates in the period 8–12 weeks, irrespective of the protein level to 8 weeks. During the period 8–12 weeks calves given the high-protein diet, after receiving a low-protein diet to 8 weeks, tended to gain weight at a faster rate than those given the high-protein concentrate throughout. After adjustment for differences between treatment groups in mean concentrate consumption and mean live-weight at 8 weeks, the live-weight gain from 8 to 12 weeks was significantly greater in calves given the high-protein diet after 8 weeks.

3. In Experiment 5, a significantly lower growth rate was obtained when concentrate intake was restricted to a maximum of 2 kg./day than when given ad libitum. Calves given the concentrates containing 15·9% or 20·6% crude protein gained weight significantly faster than those given the concentrate containing 12·1% crude protein, at both levels of feeding, after live-weight gain was adjusted for differences between treatment groups in mean food consumption and live-weight at 1 week.

4. It is concluded that no advantage is obtained by giving a concentrate containing more than 15·9% protein to Friesian heifer calves weaned at 5 weeks of age. The results indicate clearly the importance of an adequate supply of energy in the diet of the ruminant calf if maximum live-weight gain is to be achieved.

Energy exchanges of veal calves fed a high-fat milk replacer diet containing different amounts of iron

1. A total of 33 energy balance trials was conducted with veal calves offered a high-fat milk replacer diet containing 10, 20, 40 or 100 mg iron/kg DM.

2. There were no significant differences in weight gain, food conversion or energy retention between calves receiving 20, 40 or 100 mg iron/kg DM in their diet. Calves receiving only 10 mg iron/kg gained weight and retained energy at significantly lower rates than those in the other groups.

3. The metabolic heat production of calves receiving the liquid diet was greater than that of calves given the same amount of gross energy from a barley diet. The recommended air temperature of about 20°C for veal calf houses is therefore unnecessarily high.

The effect of milk substitute concentration upon the intake, digestion and growth of calves

A total of 40 individually-penned British Friesian male calves were offered milk substitutes ad libitum from 2 days until 12 weeks of age. Ten milks were reconstitued from either liquid or spray-dried skim milk and a fat-filled (500 g fat per kg) powder and contained 80, 110, 140, 170 or 200 g dry matter (DM) per kg liquid. A further six calves were used in a randomized-block experiment to measure the digestibility, absorption and retention of the diets containing 80, 140 and 200 g DM per kg.

There are no significant differences in the intake, growth rate, digestibility, absorption or retention between calves given milk substitutes reconstituted from liquid or spray-dried skim milk.

At all ages, as the DM concentration of the milks increased, liquid intake decreased but DM intake and live-weight gain increased. The mean live-weight gain was 0·99, 1·13, 1·16, 1·28 and 1·27 kg/day for calves given the milk substitute diet at concentrations of 80, 110, 140, 170 and 200 g DM per kg, respectively. The DM intake to live-weight ratios were constant at all ages when live weight was expressed to the power of 0·61.

No significant adverse effect of the diets was evident from the fortnightly monitoring of jugular blood samples for packed cell volume and concentrations of glucose, urea-N, Na, total protein, albumin, globulin and haemoglobin; nor from faecal consistency, rectal temperature, heart rate and respiration rate.

There was no indication that age affected digestibility, except that digestive efficiency was reduced in calves with diarrhoea, particularly at 2 to 4 weeks of age; nor that dietary concentration influenced digestion or absorption. The true absorption of N, Ca and P from the milk diets was high with mean coefficients of 0·99, 1·01 and 0·95 respectively. The main endogenous losses of N and P occurred through the urine and of Ca through the faeces.

The nutrition of the veal calf 6. The effect of ultra-high (68 per cent) fat milk powders added to liquid skim milk, and a comparison with spray-dried skim milk powder containing 20 per cent margarine fat

1. 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.

The nutritive value of cooked potato in liquid and creep diets for early-weaned calves

1. In three experiments, 112 7-day-old British Friesian male calves were used in performance and digestibility trials to evaluate dried cooked potato in liquid and creep diets.

2. A 15% depression in growth rate for each 10% inclusion of cooked potato flour in liquid diets was recorded from 4 to 21 days and the faeces of potato-fed calves also tended to be less solid. Over the whole feeding period, liquid diets containing up to 20% potato did not significantly depress performance to weaning at 35 days.

3. Only when a liquid diet containing potato starch was introduced prior to 4 weeks of age was daily live-weight gain markedly depressed.

4. Incorporating potato starch in milk diets did not influence creep intake.

5. Calves offered a creep diet containing 40% cooked potato flake ate less, but grew faster than calves given a diet containing 40% flakedmaize. At constant intakes of creep, daily gains were 14 to 18% greater on the diet containing potato flake.

6. The apparent digestibility of gross energy and nitrogen was 0·67 and 0·66 for the flaked maize creep and 0·71 and 0·69 for the potato creep. Digestible energy and digestible nitrogen values were 12·7 MJ and 18·2 g/kg dry matter for the maize diet and 13·0 MJ and 19·0 g/kg dry matter for the flaked potato diet.

7. The incidence of bloat was higher for calves fed on potato than for those fed on maize.

Effect of supplemental lactoferrin with ferrous iron on iron status of newborn calves

Data for 18 male and 18 female calves, born from primiparous and multiparous cows, were collected to determine the effect of supplemental lactoferrin and FeSO4 for 5 d after parturition on the Fe status of calves. Dietary treatments were 1) untreated, 2) 40 mg of Fe/d as FeSO4, and 3) 40 mg of Fe as FeSO4 plus 5 g of lactoferrin/d. Blood hematocrit and hemoglobin of calves born from primiparous cows at d 1 of age were lower than those of calves born from multiparous cows, but not different from those of their dams. Blood hematocrit and hemoglobin of male calves at d 1 of age were lower than those of female calves. Plasma Fe of primiparous cows at parturition was lower than that of multiparous cows, but plasma Fe of calves was not affected by parity of dam and sex of calf. Blood hematocrit and hemoglobin of untreated calves decreased from 1 to 10 d of age. Blood hematocrit and hemoglobin of calves treated with Fe of Fe plus lactoferrin increased from 2 to 10 d of age. Blood hematocrit and hemoglobin of calves treated with Fe plus lactoferrin were higher than those of calves treated with Fe at d 6 of age. Plasma Fe of calves treated with Fe or Fe plus lactoferrin increased temporarily at d 2 of age. Plasma Fe of calves treated with Fe plus lactoferrin at d 2 of age was lower than that of calves treated with Fe, but, at d 6 and 10 of age, plasma Fe of calves treated with Fe plus lactoferrin were higher.

Effect of twinning and supplemental iron-saturated lactoferrin on iron status of newborn calves

Data from 53 calves by embryo transfer were collected to determine the effect of twinning and supplemental Fe-saturated lactoferrin or FeSO4 for 5 d after parturition on iron status of calves. Blood hematocrit and hemoglobin of multiple calves born from multiparous cows at d 1 postpartum were lower than those of single calves born from multiparous cows, although those of their dams were not different. Plasma Ca, inorganic P, Mg, Zn, and Cu were similar for single and multiple calves or for calves born from primiparous and multiparous cows. Blood hematocrit and hemoglobin of untreated calves decreased from 1 to 6 d postpartum. Blood hematocrit of calves treated with 40 mg of Fe/d as FeSO4 increased from 1 to 10 d postpartum, and blood hemoglobin of calves treated with 20 or 40 mg of Fe/d as ferrous Fe increased from 1 to 10 d postpartum. Blood hematocrit and hemoglobin of calves treated with 20 mg of Fe/d as Fe-saturated lactoferrin remained nearly constant for 10 d postpartum. Serum Fe of calves increased immediately after the treatment with 20 or 40 mg of Fe as FeSO4, but serum Fe of calves treated with lactoferrin was not affected. Thus, ferrous Fe may be more effective than Fe-saturated lactoferrin in elevating blood hematocrit and hemoglobin in newborn calves.

Occurrence of iron deficiency in growing cattle

Occurrence of iron (Fe) deficiency anaemia was investigated in 33 farms in 443 veal calves (group VC; 83% males and 17% females) fed whole, defatted or butter milk or milk powder without or with supplements and in 72 age- and weight-matched bull calves (group BC) fed roughage, concentrates with mineral and vitamin supplements. In group VC plasma Fe concentration was much more frequently decreased and total iron binding capacity was much more frequently increased than in group BC. In group VC haemoglobin concentration (Hb), packed cell volume (PCV) and red blood cell number (RBC) in 18, 23 and 3%, respectively, of calves were below--2SD of the mean of reference values (Hb: 105 +/- 14 g/l, PCV: 0.28 +/- 0.04 l/l, RBC: 8.2 +/- 1.0 T/l [means +/- 2 SD]), shown in another study to remain stable throughout the growth period when veal calves were fed 52 mg Fe/kg milk replacer. In contrast, in calves of group RC only 3% of Hb values, 3% of PCV and 1% of RBC were below reference values. Fe deficiency anaemia is therefore a rather frequent problem in veal calves, but not in young bulls, fed roughage, concentrates and mineral/vitamin supplements.

Blood studies and performance among calves reared by different methods

Three methods of feeding calves were compared as follows: 1) milk replacer only with restricted movement, 2) milk replacer only with freedom of movement, and 3) hay, grain, and water with freedom of movement. No significant differences were noted for variables of acid-base balance (sampled while resting). An Fe deficiency, microcytic, hypochromic anemia, developed in the calves receiving milk replacer only. Average daily gain, carcass grade, and sale price were superior for calves receiving only milk replacer with freedom of movement as compared with those with restricted movement. A fourth method (calves nursing cows), represented by calves having a different origin, was compared as a supplemental group. Absolute numbers for lymphocyte and neutrophils were significantly higher for calves nursing cows than for calves reared by the other methods.

Some aspects of extra iron supply in veal calf fattening

Extra iron (5 ppm) in a normal commercial milk replacer given from the end of the sixth week until the end of the sixteenth week of the fattening period influenced food conversion positively without a loss in meat quality. Even when the extra iron was given to the end of the fattening period there was no perceptible improvement of the haematological status of the calf, though liver iron concentration was increased. During all the experiments no stainable iron could be found in bone marrow smears. Iron and copper concentration measured in liver biopsies appeared to give reliable information about, respectively, iron and copper status of the veal calf. In relation to the colour of the meat at slaughter the blood haemoglobin concentration during the fattening period was found to be the most reliable parameter.

Growth, health, and blood glucose concentrations of calves fed high-glucose or high-fat milk replacers

The influence of age, carbohydrate-fat ratios of milk replacers, and development of ruminal function on growth, health, and blood glucose concentrations were evaluated in calves. Colostrum-fed, 3-day-old Holstein bull calves were fed to 12 wk on one of three dietary treatments: 1) a high carbohydrate, low fat (60.5% glucose, 9.5% lactose, and 3% lard) milk replacer; 2) a low carbohydrate, high fat (23% glucose, 12.5% lactose, and 30% lard) milk replacer; and 3) weaning at 6 wk of age from high-fat replacer to a standard calf starter. The high fat milk replacer was superior to low fat milk replacer for total weight gains and efficiency of feed conversion. Rates of weight gain of starter calves were similar to those of calves fed low fat. Calves fed the diet with low fat had a high incidence of diarrhea, an occasional outbreak of a yeast-related ethanol intoxication syndrome, and high concentrations of glucose in urine. Irrespective of milk replacer composition or development of ruminal function, plasma and whole blood glucose concentrations declined rapidly in the first 6 wk. Corpuscular glucose declined steadily with age in all calves. This age-related decrease of blood glucose concentration of calves seems to be a constitutive phenomenon.

Dietary fibers and supplementary iron in a milk replacer for veal calves

Thirty 1-wk-old male Holstein calves were allotted randomly to six groups into a 3 X 2 factorial design. The control diet was skim milk, whey, tallow, vitamins, and minerals. Either Alpha-Floc or pectin was added at 5% dry matter. Supplementary iron was added at 30 and 50 ppm (dry basis). The six diets were fed for 14 wk. Calves without supplementary iron were mildly anemic at 6 wk and severely at 14 wk (7 and 5 g/dl hemoglobin). At 14 wk, both fibers had decreased blood hemoglobin in calves given supplementary iron. Feed refusal began at 8 wk with the appearance of anemia for calves unsupplemented with iron, but both Alpha-Floc and pectin decreased feed refusal. Supplementary iron practically eliminated feed refusal. Supplementary iron improved average daily gain and feed conversion, but dietary fibers had no effect. Adding Alpha-Floc and pectin to the diets reduced frequency of diarrheic feces. Mean carcass weight of calves fed supplementary iron was 11.6% higher than that of unsupplemented calves. Supplementary iron decreased liver lipids and increased glutamic oxaloacetic transaminase activity in blood plasma.

Developmental changes in serum ferritin concentration of dairy calves

Serum ferritin concentration of nursing calves was measured by a two-site immunoradiometric assay to assess developmental changes and to evaluate relationships of serum ferritin with iron-related blood characteristics. Serum ferritin concentration of calves was low at birth and elevated slightly at 3 days of age. From 1 wk of age onward, serum ferritin concentration of untreated calves and calves fed only whole milk for 4 wk decreased and remained low throughout the nursing period. This finding almost coincided with hematological characteristics. However, that nearly normal hematological measures and weight gain persisted and that they did not develop any anemic symptom indicate that serum ferritin concentration is more sensitive than other hematological characteristics to iron depletion. However, serum ferritin concentration of calves administered 130 mg of ferrous fumarate (40 mg iron) daily from 3 to 22 days of age or injected with 4 ml of iron-dextran intramuscularly (400 mg iron) at 3 days and 2 wk of age increased sharply just after treatment and persisted high for 2 to 6 wk of age. However, there was large variation between animals for serum ferritin concentration. Thus, it seems likely that serum ferritin concentration is an index for monitoring prelatent iron deficiency of calves.

[Oral and intramuscular ferridextran intervention in male breeding calves. 3. Nutrient and feed uptake during the stay in the weaning range]

The influence of an oral and intramuscular Fe-application on the nutrient (dry matter, energy, protein and iron) and feed intake resp. (skim milk, calf rearing feed and lucerne hay) of calves during their 56-day stay in the weaning range of a rearing farm was investigated. There were significant differences between the test animal groups with regard to nutrient intake; their levels had the following sequence: B (Fe orally) greater than C (Fe i.m.) greater than A (without Fe-supplement). In the calf rearing organised as graded production the effect of iron intervention on nutrient intake probably occurs as a consequence of the reduction of the depression of feed consumption caused by disease. By comparison with the nutrient and feed intake of weaning calves from a different rearing farm one can further conclude that this secondary effect of iron intervention does not only depend on the more or less rapid remedy of the differently marked states of iron deficiency of the calves but also on the other rearing conditions (particularly the drinking regime). It is improbable that the oral ferridextran intervention (200 mg Fe/d) carried out provokes excessive iron supply.

[Oral and intramuscular ferridextran intervention in growing male calves. 1. Hematologic reactions]

195 calves were at random divided into 3 test groups and received oral (200 mg Fe/d) or intramuscular (1.0 and 1.5 g Fe on the 3rd and 36th day of the period of fluid feeding) applications of ferridextrane or no additional quotas of iron (control group) and a limited supply of milk replacer and skim milk as well as ad libitum supply with concentrated feed and dried green fodder during their 56-day period in the range of the rearing farm where the calves receive fluid feed. Iron intervention was carried out without considering the individual iron content of tissue. Its effect was evaluated according to the hemoglobin content (Hb), the hematocrit (Hc) and the mean corpuscular hemoglobin concentration (MCHC) in venous puncture blood. There was no difference between the test groups as to the stabling conditions (affiliation to race and genotype, birth weight, age and live weight resp. at the beginning of the experiment, live weight gain before the beginning of the experiment). In the control group Hb, Hc and MCHC were analogous to previous epidemiologic investigations concerning the anaemia of calves. The ferridextrane interventions carried out resulted in a raised level of Hb and Hc and diminished anaemia frequency as well as the shortened duration of anaemia in this rearing period.

The nutritive value of non-milk proteins for the preruminant calf. The effect of replacement of milk protein by soy-bean flour or fish-protein concentrate

1. Milk-substitute diets, in which 330-360 (L) 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 610 g/kg milk protein from this FPC without markedly affecting performance, especially if an effective growth promoter is included in the diet. The beneficial effect of Grofas appeared to result from the reduction in the fermentation of the oligosaccharides of SF, which was reflected in higher digestibility particularly of fat and absorption of Ca and in reduced thickness of the intestines.

The effect of different diets including those containing soya-bean products, on digesta movement and water and nitrogen absorption in the small intestine of the pre-ruminant calf

1. Preruminant calves, fistulated in the abomassum and distal ileum, were given by infusion into the abomasum, at intervals of 2-3 d, single experimental feeds of cow's milk or a synthetic milk diet in which the protein source was casein or a soya-bean product. Polyethylene glycol (PEG) and phenol red were included as markers. 2. After infusion of the experimental feed, measurements were made of transit time from proximal duodenum to distal ileum and mean ileal flow-rates for the first 3 and 21 h after food residues reached the distal ileum. PEG recoveries for these two periods and net nitrogen absorption up to the distal ileum were also determined. In some experiments sodium, potassium and magnesium concentrations and numbers of viable bacteria in ileal digesta were determined. 3. Measurements of passage of digesta, recovery of marker and net N absorption did not differ greatly between calves given cow's milk and the synthetic milk diet containing casein. Compared to the casein-based diet, a diet based on heated soya-bean flour given to a calf for the first or second time produced a somewhat higher ileal flow-rate and a significantly lower net N absorption. Net N absorption was even lower when a calf received a diet containing unheated soya-bean flour. 4. Calves given the diet containing heated soya-bean flour on several occasions appeared to develop a sensitivity to the flour, and after further feeds containing it they had significantly higher rates of ileal flow (accompanied by correspondingly high rates of Na and K flow), lower small intestine transit times and lower net N absorption values than similarly fed unsensitized calves. They also had significantly lower rates of passage of marker in the first few hours after food residues reached the ileum, indicating inhibition of abomasal emptying. Over all, the changes indicated a severe disturbance in digestive function which was not caused by abnormal bacterial growth and may have been due to a gastrointestinal allergy. 5. Diets prepared from water-extracted flour and from soya-bean-protein isolate also led to digestive disturbances in sensitized calves, but those containing concentrates prepared by extracting soya-bean meal with hot aqueous ethanol did not.

The protein requirement of the ruminant calf. 4. Nitrogen balance studies on rapidly growing calves given diets of different protein content

1. Twelve Friesian bull calves were weaned at 5 weeks and reared to approximately 18 weeks of age on diets consisting mainly of concentrates containing 209 (HP), 169 (MP) or 130 (LP) g crude protein/kg dry matter. Hay was removed from the diet when the calves reached 10 weeks of age.

2. In relation to metabolic body size, daily dry-matter intake rose rapidly until the calves were about 9 weeks old and then tended to level off at between 80 and 100 g dry matter/kg0·73.

3. After adjustment for treatment differences in concentrate intake, the live-weight gains of calves given diets HP or MP were significantly greater, both from 1 to 12 weeks and from 1 to 16 weeks of age, than those of calves given diet LP.

4. Digestibility trials made twice on each calf, when given solely the concentrate diet and when live-weight gain was about 1 kg/d, showed no differences in dry-matter digestibility, but the apparent digestibility of crude protein increased with the protein content of the concentrate mixture. The true digestibility coefficient of dietary protein was estimated to be 0·880, with no difference between diets. Metabolic faecal nitrogen excretion was estimated to be 3·43 g N/kg dry matter ingested.

5. At the mean intake of digestible energy/kg0·73, N balance was significantly greater with diets HP and MP than with diet LP. Endogenous urinary N excretion was estimated to be 220 mg/kg0·73 and the apparent biological value of protein was 0·851 when diet LP was given.

6. The results confirm the importance of a balanced relationship between energy and protein intakes in the diet of the rapidly growing calf. It is concluded that the crude protein content of the diet can be reduced to below 172 g/kg dry matter, and possibly as low as 153 g/kg, for calves of 122 kg live weight to achieve weight gains of 1 kg/d, when given an all-concentrate diet. This lower protein level would be expected to result in the maximum efficiency of utilization of the dietary energy and protein.

EFFECTS OF INCREASING THE ENERGY VALUE OF A WHOLE MILK DIET FOR CALVES. II. GROWTH, FEED UTILIZATION, AND HEALTH

In each of three growth trials, Holstein male calves grew significantly faster (P < 0.05) when whole milk was supplemented with the energy sources glucose (cerelose) or butterfat. In two trials, growth rates of 819 and 829 g/day were obtained on whole milk with energy values of 21.7 and 23.8 kcal digestible energy (DE)/g digestible crude protein (DCP), respectively, compared with gains of 1,023 and 986 g/day obtained by increasing the dietary energy value to 28 kcal DE/g DCP by glucose supplementation. Further increases in energy:protein ratio tended to reduce liquid intakes and growth rates, but adjustment by covariance to equal protein intakes showed significantly higher growth rates (P < 0.05) on supplemented milk with 31–32 kcal DE/g DCP than on normal whole milk. Protein consumed per unit weight gain was decreased significantly (P < 0.05) by increasing the energy of a whole milk diet, but very high levels of added cerelose (> 13% of the liquid diet) caused severe diarrhea and reduced intakes and growth. The addition of 6% cerelose was well tolerated by calves and this level of supplementation produced more efficient growth per unit of protein consumed than lower levels. It was concluded that more suitable energy: protein ratios than commonly used in liquid diets for calves may result in improved protein utilization and thus have economic value.

Iron metabolism in the veal calf. The availability of different iron compounds

1. The haematological status of Ayrshire bull calves reared on fat-supplemented skim milk from about 17 d of age has been examined. The calves were moderately anaemic after an 11-week experiment and it was shown that their performance was related to their blood haemoglobin concentration.

2. The relative availabilities of iron from FeSO4, ferric citrate, ferric-ethylenediaminetetra-acetate and iron phytate were compared at a supplementary dietary concentration of 30 μg Fe/g. No significant differences were noted between the three soluble Fe sources but the Fe of the insoluble iron phytate was less available.

3. The decreases in blood haemoglobin concentrations in all calves were greatest in the early weeks of the experiment. In calves given supplementary Fe, however, there was generally an improvement in haematological status after 6 weeks. Plasma Fe concentrations fell to 0·20 μg/ml in the most deficient animals. Total Fe binding capacities averaged about 10 μg Fe/ml in the later stages of the experiment.

4. Some of the calves were copper-deficient, and in some animals the effects of dietary Cu supplementation on both Cu and Fe metabolism were studied. About 50% of the supplementary Cu was retained in the livers of the calves.

5. A dietary intake of 40 μg Fe/g milk powder appears to be sufficient to prevent all but a very mild anaemia, provided the Fe is presented in soluble form.

The effect of environmental temperature on the performance and health of the pre-ruminant and ruminant calf

1. 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 maintainted at a mean environmental temperature of 21° and forty at 14·5°. 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 gien either ad lib. or at a restricted level. The calves were slaughtered at about 100 d of age.

2. The incidence of a high rectal temperature (> 39·39°) 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 enviromental temperature of 21° than for thosekept 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' environmentaltemperature 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 weight/kgO·73.

4. Live-weight gain was much lower for the ruminant calves, but was unaffected by environ-mental temperature. Daily dry-matter intake from liquid diets given ad lib. did not differ be-tween 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 weight0·73, 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 weight0·73, 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 21° than for those maintained at 14·5°.

6. It is concluded that there is no advantage to be gained from rearing calves at an environ mental temperature above 14·5°, unless increased fat deposition is required in veal calves.

The nutrition of the veal calf. 4. The effect of offering roughage on health and performance

1. Eighteen bull calves, comprising twelve Ayrshires, three Friesians and three Jerseys were 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.

6. It is concluded that the calf shows very little desire to eat roughage when given a good- quality 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 nutrition of the veal calf. 2. The effect of different levels of protein and fat in milk substitute diets

1. Seventy-two bull calves, comprising forty-eight Ayrshire and twelve each of the Friesian and Jersey breeds, were used in a randomized block experiment. They were reared from birth on liquid diets, offered in two feeds daily, at either restricted or ad lib. levels. The restricted level of feeding was such that sufficient diet was fed to allow for a weight gain of I kg/d, and the calves given this level of feeding were slaughtered at a weight 77 kg above the mean birth weight of the breed. The calves given the diets ad lib. were slaughtered at 22 % of mature cow weight of the breed.

2. Three milk substitutes, based on spray-dried skim-milk powder, spray-dried whey powder and margarine fat, were compared. Two of these were high-protein diets (26–29 % protein) designed to contain either 20 % fat (LFHP) or 30 yo fat (HFHP) and the other was a low-protein diet (19 % protein) designed to contain 30 yo fat (HFLP).

3. Age at slaughter was lowest for diet HFHP and highest for diet HFLP. Total dry-matter intake did not differ between treatments, but daily dry-matter intake was lower on diet HFLP. Relative weight gain did not differ between diets LFHP and HFHP but was much greater than that for diet HFLP. After adjustment for differences between treatments in mean daily dry-matter intake, relative weight gain tended to be highest for diet HFHP. No difference occurred between treatments in the incidence of diarrhoea and of a high rectal temperature (> 39.33°). However, mean rectal temperature was higher for calves given the HFHP diet than for those given the HFLP diet.

4. Digestibility and nitrogen and calcium balance trials were made on six of the replications of Ayrshire calves at 4 and 10 weeks of age. Dry-matter intake at 10 weeks of age was lower for calves given diet HFLP than for those given the other diets. Apparent digestibility of fat tended to be lower for the HFLP diet. True digestibility of protein did not differ significantly between treatments. Apparent digestibility of lactose was highest for the HFLP diet.

5. No difference occurred between the two high-protein diets (LFHP and HFHP) in N or Ca retention, but N and Ca retention by calves on the low-protein diet (HFLP) was markedly lower. Daily faecal N excretion was unaffected by treatment, but daily urinary N excretion was lower and the biological value of the protein was higher for diet HFLP than for diet LFHP, with the corresponding values for diet HFHP being intermediate between the two. N reten tion/100 g weight gain was lower on diet HFLP, lower at 4 weeks of age than at 10 weeks, and lower at the restricted than at the ad lib. level of feeding at 4 weeks of age. Metabolic faecal N and endogenous urinary N at 4 weeks of age were estimated as 0.192 g/100 g dry-matter intake and 192.9 mg/kg0.72 live weight respectively.

6. Haematological findings showed that the high-fat diets (HFHP and HFLP) resulted in a slower rate of decline in packed cell volume and haemoglobin content with age. The low protein diet (HFLP) resulted in a lower rate of increase with age in the percentage of lymphocytes. Diet HFHP resulted in a decline with age in the percentage of eosinophils compared to a marked rise with the other two treatments.

7. Carcass weight did not differ between treatments, but perirenal fat deposition was much higher for the calves given the high-fat diets (HFLP and HFHP).

8. It is concluded that dietary fat is not a readily available source of energy for increasing N retention in calves given large quantities of milk substitutes, based on milk products with added fat. Unless additional fat deposition in the carcass is required, no advantages in weight

The nutrition of the veal calf. 3. A comparison of liquid skim milk with a diet of reconstituted spray-dried skim-milk powder containing 20 per cent margarine fat

1. Twenty-four bull calves consisting of fifteen Friesians and nine Ayrshires in a randomized block experiment were reared from birth on liquid diets offered ad lib. in two feeds daily to a slaughter weight equivalent to 22 % of mature cow weight of the breed.

2. The three diets given after the calves had received 7 kg whole colostrum were (a) fresh liquid skim milk containing 0.1 % butterfat, (b) a ‘high-fat’ diet containing reconstituted spray-dried skim milk and 2.8 % margarine fat, and (c) the ‘high-fat’ diet for 14 d from birth followed by liquid skim milk. All calves received supplements of magnesium and iron, and vitamins A, D and E. Digestibility and balance trials were made on nine calves of each breed at both 4 and 10 weeks of age. Certain observations were made at slaughter.

3. Dry-matter and gross energy intakes of calves given the skim-milk diet were greater than for those given the ‘ high-fat ’ diet. Daily weight gain, efficiency of food conversion, incidence of a high rectal temperature ( > 39.33°), mean rectal temperature and faecal dry-matter content were greater for the calves given the ‘ high-fat ’ diet. Age to slaughter and incidence of diarrhoea were much greater for the calves given liquid skim milk.

4. Apparent digestibility of lactose and apparent absorption of ash and calcium were greater withthe ‘high-fat ’diet, but no difference occurred in apparent digestibility of dry matter or protein. Metabolic faecal fat excretion was estimated from the intercept of the relationship between apparently digested fat and fat intake for the calves given the liquid skim-milk diets; the values obtained ranged from 29 mg/kg live weight for Friesian calves at 10 weeks to 49.5 mg/kg for Ayrshire calves at 4 weeks. The true digestibility of the fat was estimated.

5. No difference in Ca or nitrogen retention occurred between diets, but urinary N excretion and N retention/100 g gain in weight were markedly higher and concentration of N in the urine was much lower for calves given the skim milk.

6. Perirenal fat deposition per unit of metabolic body size was 168 % greater for calves given the ‘ high-fat ’ diet. Kidney weight and skin weight were greater for the calves given the liquid skim-milk diet. The increased kidney weight was related to the very large urine output of the calves given skim milk.

7. In comparison with Ayrshire calves, Friesian calves were much less susceptible to the adverse effects of liquid skim milk, having a lower incidence of diarrhoea and faeces of a higher dry-matter content, but they did have a higher incidence of lung lesions. Friesian calves also had a higher relative growth rate, efficiency of feed conversion, mean body temperature, faecal pH, apparent absorption of Ca, retention of N and Ca per unit of metabolic body size and killing-out percentage, but lower skin weight per unit of metabolic body size. Perirenal fat per unit of metabolic body size did not differ between breeds.

Nitrogen balance studies with the milk-fed lamb. 5. Effect of frequency of feeding

1. Thirty-three cross-bred lambs were given reconstituted dried whole cow's milk from 1 week of age at different levels of intake and at different frequencies of feeding.

2. Feeding frequency had no effect on live-weight gain, N retention or total body composition.

3. Lambs given two feeds daily had significantly heavier abomasums than pair-fed lambs given six feeds daily.

4. The weights of fat, protein (N x 6.25) and water in the body were closely related to empty body weight; body composition (% of empty body) was not significantly affected by the level of milk intake or by the rate of growth.

5. Live-weight gain was closely related to energy intake (r = +0.99) and to N retention (r = +0.97). A live-weight gain of 100 g was associated with an intake of 511 kcal and a N retention of 2.28 g N.

Nitrogen balance studies with the milk-fed lamb. 4. Effect of different nitrogen and sulphur intakes on live-weight gain and wool growth and on nitrogen and sulphur balances

1. Sixteen male cross-bred lambs were given four diets, which differed in the ratio of protein to energy. The protein contents of the diets (on a dry-matter basis) were: 6.1% (diet A), 11.9% (diet B), 17.5% (diet C) and 22.9% (diet D).

2. The experimental period of 7 weeks was divided into two 2-week periods (periods 1 and 2), and one 3-week period. The diets given to the lambs were changed between period 1 and period 2. In period 3 all the lambs were given the same dietary treatment as in period 2.

3. The daily feed intake of the lambs was regulated according to live weight. Adjustments were made at the beginning of period 1 and of period 2. The level of feeding was 121 kcal/kg live weight 24 h. In period 3 the intake was the same as in period 2.

4. Diet digestibility, live-weight gain, and nitrogen and sulphur balances were calculated for each lamb on each diet in all the periods. Wool growth on sample areas was measured over a 2-week and a 4-week period. These wool growth periods corresponded to treatment period 1, and treatment periods 2 and 3, respectively. At the end of the experiment the lambs were slaughtered and the composition of carcass and organs was determined.

5. The mean digestibilities of energy, N, ether extractives and dry matter increased significantly as the protein content of the diet increased.

6. The live-weight gain increased with increasing protein content of the diets, but only the difference between the means for diet A and all other diets was significant.

7. The N and S balances increased with increasing intake of apparently digested N and S, and all differences between the means for individual diets were highly significant.

8. There was a significant correlation between N balance and live-weight gain for each diet. However, when compared at the same late of gain, N balance increased as the protein content or the diet increased.

9. Wool growth on the sample areas increased with an increase in the protein content of the diet and all differences between the means for individual diets were highly significant. There were no significant differences between the dietary treatments in their effect on the N and S contents of the wool. The mean values were 15.7% N and 2.87% S.

10. The retention of N in the wool grown did not account for the increased N retention on the diets of higher protein content. The lambs given diet A, retained more N and S in wool than was supplied by the diet.

11. The percentage of fat in the carcass decreased, and the percentage of protein increased as the protein content of the diet increased. The percentages of moisture and ash were not significantly affected by the dietary treatments.

12. The percentages of moisture in the liver, pancreas and muscle decreased and the percentages of protein in the liver and muscle increased as the protein content of the diet increased. The ratio of N in the organs (with the exception of the spleen and pancreas) to N in the carcass was highest for lambs given the diet with least protein (diet A).

Rumen development in the calf. 1. The effect of diets containing different proportions of concentrates to hay on rumen development

1. Thirty Ayrshire bull calves were used in an experiment to study the effects of diets containing different proportions of concentrates to hay on rumen development at 12 weeks of age. In addition, six milk-fed calves were slaughtered at 3 weeks of age for comparison. 2. Restriction of the maximum daily allowance of concentrates to the lower levels was accompanied by an increase in the voluntary intake of hay, but the performance of calves from 3 to 12 weeks of age was significantly better in calves given the high-concentrate diets. 3. The weight of contents of the reticulo-rumen increased from 0.7 kg at 3 weeks of age in the milk-fed calf to 7.7 kg and 10.9 kg at 12 weeks in calves given the high-concentrate and high-roughage diets respectively. Between 68 and 79% of the total contents of the alimentary tract was contained in the reticulo-rumen of the ruminant calf. The weight of contents of the omasum was significantly greater in calves given 1.36 kg concentrates/day than in those given either 0.45 or 2.27 kg concentrates/day. Equations were developed from the results by which the weight of contents of the various parts of the alimentary tract, and hence empty body weight in the live animal, can be determined from a knowledge of the live weight and daily consumption of concentrates and hay, 4. Volume displacement of the reticulo-rumen tended to increase with increase in the proportion of hay in the diet. The volume displacement of the omasum increased in response to concentrate intake up to a maximum of 1.36 kg/day and thereafter declined, but the nature of the diet had no significant effect on the volume displacement of the abomasum. 5. Calves given the high-concentrate diets had a significantly greater weight of reticulo-rumen tissue at 12 weeks than those given the high-roughage diets. 6. Whereas the thickness of the muscular wall of the rumen did not differ significantly between treatments, there was an increase in the length and density of papillas, particularly in the anterior dorsal and ventral sacs of the rumen, as the intake of concentrates was increased. The results show the marked relationship between the performance of the animal and an advanced stage of development of the rumen papillas.