The subcutaneous, intermuscular and cavity fat depots of the half carcasses of 15 Large White × Landrace castrated male pigs, forming a growth series from 8 to 62 kg live weight, were dissected. Seventy individual muscles of these pigs were analysed for intramuscular fat content. The growth rates of each of the four fat depots, relative to total fat, were similar. Subcutaneous fat was the predominant fat depot over the growth range studied. Both intramuscular fat and non-fat dry matter grew faster than the entire muscles containing them. Growth gradients for the intramuscular fat of muscle groups, relative to either total intramuscular fat or to total fat, were similar to those for the entire muscles. The growth gradients for muscle groups were affected by neither the growth of the contained intramuscular fat nor the contained non-fat dry matter. Intramuscular fat density, but not non-fat dry-matter density, varied throughout the carcass. The fat content of muscles was highest in those that could be useful as subcutaneous insulators.

Six pairs of gilts were taken at first mating. One of each pair was given about half the A.R.C. recommended amounts of protein and energy during pregnancy and lactation until she became anoestrus (thin group). The other gilt of each pair was given the same amount of protein, but double the amount of energy (standard group).

All the thin sows lost condition and became infertile. Their appearance conformed to that of sows with the ‘thin sow syndrome’. This took up to three reproductive cycles. There was no clear effect on the number of piglets born, but the litters of the thin sows contained an increasing proportion of small piglets. One of the thin sows died in her second pregnancy. The standard sows performed well producing an average of 10·3 piglets weighing 1·4 kg over three parities.

There were no differences between the two groups in their digestive efficiency. The thin sows retained less nitrogen in the later stages (days 80–100) of their first pregnancy than did the standard sows.

There were no differences between the groups in milk production during the first lactation when litters were standardized at eight piglets. There was some evidence that in the second lactation the thin sows secreted less fat and lactose.

The five remaining thin sows were repleted at the end of the experiment when their average weight was 96 kg. They were mated as quickly, produced litters which were as large, and piglets which were as heavy as those produced by the standard sows whose mating weight was 182 kg.

A total of 124 pregnant multiparous sows were allocated to either control or treated groups. The treated sows were given 175 μg of an analogue of prostaglandin F2α (I.C.I. Ltd compound no. 80996) on day 113 of gestation. Gestation lengths for the control and treated groups were 116·3 ± 1·44 and 114·0 ± 0·31 days respectively. Two thirds of the treated sows farrowed between 24 and 32 h following administration of the drug. The number of live and stillborn pigs per litter did not differ between the two groups but birth weights were significantly higher in natural than in induced farrowing litters (1·36 v. 1·26 kg). Piglet mortality up to 10 days of age was significantly less in control litters (0·74 v. 1·61). The subsequent reproduction of sows was not affected by treatment with the prostaglandin analogue

The experimental animals were sows which had been made thin by underfeeding for several parities (thin sows), and siblings which had received adequate energy (standard sows).

The energy metabolism of three thin anoestrous and three non-pregnant standard sows were measured at 20 and 5 °C. There were no differences between the two groups of sows. The fall in temperature increased the average maintenance requirement by 60% from 476 to 753 kJ/kg0·75/day (1192–1922 kJ/kg0·56/day).

The tissue insulation of the thin sows was 28% lower than that of the standard sows, although this difference was not statistically significant. The thin sows compensated by having a better external insulation. The average total body conductance was 306 kJ/m2/°C/day.

The standard sows were in positive nitrogen balance (+ 4·2 g/day, 95% confidence limits 1·5 to 7·0 gN) and the thin sows in negative nitrogen balance (– 4·4 g/day, 95% confidence limits – 2·1 to – 6·8 g N) at energy equilibrium. It is suggested that this difference might be explained if the total nitrogen requirement of the two groups of sows was similar, but that their requirement for energy was related to their body surface area.

There were no differences between the two groups of sows in their digestive efficiency, but the digestibilities of both energy and nitrogen were reduced at 5 °C.

It is concluded that the primary cause of the ‘thin sow syndrome’ is underfeeding, particularly in cold environments. Other features of the syndrome are probably a consequence of undernutrition and depletion of the body energy reserves.

Chloroplasts, 50–80% intact, were prepared from kale (Brassica oleracea L. var. Marrowstem) by rapid homogenization (3·5 sec) of deveined leaves into partially frozen buffer pH 7·4 made 0·4 M with sucrose, and separated by differential centrifugation. Chloroplasts from 10 kg leaves were administered to the rumen of a sheep and the degradation followed by analysis of the rumen fluid which was collected continuously. Particulate matter of the rumen fluid was separated on discontinuous sucrose density gradients, 8 ml each of 35, 46, 50, 65 and 75% (w/v), centrifuging at 300 g for 1 h at + 2 °C. Chloroplasts were rapidly ingested by entodiniomorphid protozoa and digested with no detectable increase in soluble nitrogen in the rumen fluid. No net production of ammonia occurred but δ-amino-valeric acid increased indicating that amino acid transformations had occurred. Chlorophyll in the ingested chloroplasts was rapidly degraded with a half-life of 50–60 min. In contrast a similar amount of soluble casein added to the rumen degraded with a half-life of 13–14 min with large increase in soluble nitrogen consisting of peptides, amino acids, ammonia and δ-amino-valeric acid. Glutaraldehyde treated chloroplasts were also ingested by protozoa, chlorophyll was rapidly degraded but there was no increase in the soluble nitrogen of the rumen fluid, including ammonia and δ-amino-valeric acid. Water disrupted chloroplasts released soluble protein and in the rumen behaved like casein, producing high proportions of ammonia and δ-amino-valeric acid. The significance of these experiments in the protection of soluble leaf protein from degradation in the rumen of pasture-fed animals is discussed.

Semen from eight Murrah buffalo bulls was collected and analysed for physical and biochemical determinants throughout the year. Depending upon the climatic conditions, the whole year was divided into four periods. The mean values of volume, density, mass motility and sperm concentration was 1·64 + 0·060 ml, 2·48±0·032 (3-point scale), 2·65±0·069 (5-point scale) and 1185 ±19·2 million/ml, respectively. The mean values of alkaline and acid phosphatases were 1238±47·4 and 1244±54·5 King-Armstrong units (KAU)/100 ml of seminal plasma. Average figures for citric acid, calcium, phosphorus, total nitrogen and non-protein nitrogen (NPN) were 507 + 14·1, 53·0±l·2, 121±4·9, 649±12·8 and 116±2·0 mg/100 ml of seminal plasma. Periods of the year had significant effect on volume, alkaline and acid phosphatases, citric acid and NPN (P < 0·01). Different correlations of physical and biochemical determinants are discussed. Of all the determinants only weight of the bull, sperm concentration and NPN were found to be positively correlated with fertility while phosphorus was negatively correlated.

A study was made of the birthcoat and the birth weight of Merino lambs, coarsewoolled Ossimi and the reciprocal crosses. The pre-natal maternal environment had a clear effect on the fineness of the birthcoat of cross-bred lambs born to Merino ewes (Ossimi × Merino) where 22·6% had fine arrays, whereas those out of coarse wool Ossimi dams (Merino × Ossimi) were all coarse like pure Ossimi lambs.

Merino birthcoats were the most highly evolved, having the highest curly tip/precurly tip ratio, whereas the Ossimi were the least evolved. Ossimi × Merino lambs had more evolved birthcoats than Merino × Ossimi. CT/Pre-CT ratios were 1·00, 2·35, 4·41 and 8·06 in Ossimi, Merino × Ossimi, Ossimi × Merino and Merino lambs, respectively.

Ossimi birthcoats had almost straight fibres. Merino × Ossimi showed a low incidence of crimp post natally, Ossimi × Merino exhibited more post-natal crimp and that in Merino predominant crimp occurred throughout.

Strong (coarse) fibres were more frequent in Merino × Ossimi whereas Ossimi × Merino possessed higher frequencies of the less strong fibres and CT/Pre-CT ratio than the other cross. The difference between the two means of the crosses was highly significant in all fibre types.

Lambs with strong fibre type arrays were heavier at birth than those with finer ones.

The quantitative estimation of ruthenium and chromium in faeces and digesta from sheep by X-ray fluorescence spectrometry is described. Estimates of calibration parameters, established by regression analysis, were applicable to a range of matrices. Lower limits of detection of 2·4 mg Ru/kg (solid), 1·8 mg Ru/1 (liquid), 1·6 mg Cr/kg (solid) and 1·1 mg Cr/1 (liquid) and precisions, expressed as coefficients of variation, of 5·4% at 17·7 mg Ru/kg (solid), 5·1% at 182·7 mg Cr/kg (solid) and 1·1% at 152 mg Cr/1 (liquid) were acceptable for the routine analysis of Ru and Cr.

The use of inert ruthenium phenanthroline (Ru-P) and inert chromium ethylenediamine tetra-acetic acid (Cr-EDTA) as solid:liquid dual phase markers in digestive physiological studies was evaluated. The specificity of Ru-P for the particulate phase of digesta, established by both in vitro and in vivo experiments, was found to be 92–98%, and in vivo recovery of intraruminally administered Ru-P in faeces was 97–101%. In vitro incubation of rumen liquor showed that concentrations of Ru-P up to 10−4 M had little effect on volatile fatty acid production rates but at 10−3 M there was virtually complete inhibition of acetate and propionate production.

Advantages of using inert Ru-P as a solid phase marker are discussed.

Determinations of sodium bicarbonate (pH 8·5) extractable P made on profiles of a sandy loam soil 7 and 8 years after fertilizer application to coconut in the Dry zone of Sri Lanka showed that the downward movement of P from concentrated superphosphate was greater than from rock phosphate (saphos). The surface layers (0–15 cm) of soil given concentrated superphosphate had higher P values (60 and 89 mg/kg for the 8th and 9th year respectively) than those given rock phosphate (3 and 16·5 mg/kg). At 40 cm depth the concentrated superphosphate treatment had 6 and 30 mg P/kg but the rook phosphate treatment had almost zero P at and below 40 cm.

Phosphorus in the soil profile 8 years after fertilizer application was fractionated by the method of Chang & Jackson. Concentrated superphosphate treatment increased the Al-P and to a lesser degree Fe-P and Ca-P. Rock phosphate treatment increased the Ca-P and to a lesser extent Fe-P and Al-P. Phosphorus concentration in the 14th leaf was significantly correlated with Al-P, Fe-P and NaHCO3-P but not with Ca-P and organic P.

The significance of the findings to phosphorus fertilizer application to coconut is discussed.

The response of three cassava cultivars to potassium fertilizer was studied in field experiments during 1972–3, 1973–4 and 1975–6. They included the local cultivar 53101 and the improved cultivars 60506 and 60447 which were F1 hybrids involving the local strain (53101) and cultivar 42074. In locations known to be low in potassium, the cassava cultivars showed only low response to K fertilizer with optimum performance at about 60 kg K2O/ha, but the local cultivar 53101 had apparently not reached its maximum tuber production even at 120 kg K2O/ha. This cultivar gave higher tuber yield increases (10–18 kg dried tuber) per unit weight of potash than the 60506 cultivar (6–10 kg dried tuber/kg K2O) while cultivar 60447 produced about 18 kg/kg K2O. Unfertilized 60506 produced average yields equivalent to those obtained from the heavily fertilized 53101 cultivar. Cultivar 60506 gave the highest dry-matter content. The improved cultivars retained more leaves than the local strain. K fertilizer enhanced the utilization index (storage root/top ratio) of the cassava cultivars.

Free amino -N estimations were used to monitor the movement of amino acids in the vascular system of sheep. The net uptake of free amino-N by portal drained viscera was measured in whole blood and compared with the net gain in the plasma flow.

In normally fed sheep eating dried grass, lucerne or silage the net gain of free amino -N in the plasma of portal blood contributed less than 80% to the total uptake in whole blood. When the protein component of the diet was added into the abomasum (casein supplement to a low nitrogen basal ration) the plasma contribution to the net gain in portal blood averaged 95%.

The results suggest that the cells as well as the plasma are involved in the transport of amino acids in blood and that in ruminants all amino acids have to be measured in blood for a quantitative calculation of the absorption from portal drained viscera.

Studies of the day-time activity of night-enclosed eland, oryx, buffalo and cattle in a hot, semi-arid area in Kenya showed that, on average, eland spent 70% of the day feeding, oryx 60% and buffalo and cattle 52%.

The distribution of activity throughout the day of all species was similar and the mobile activities of feeding and walking tended to be concentrated in the early morning and late evening.

Correlation and multiple regression analyses were used to investigate changes in the activity of the animals in relation to changes in meterological and vegetative factors. The activity of both eland and buffalo was found to be particularly sensitive to the meterological factors.

The duration of feeding for cattle and buffalo was related to the state of the vegetation, but that of the oryx was not. Similar analyses were not possible for eland.

The activity of each species could be related to mouth size, feeding habits and the effectiveness of the animals' coat in dealing with conditions of high heat load.

It is concluded that a naturally short daily feeding time and an independence of activity from the environmental heat load on the animals are advantageous characteristics for a species under domestication in a hot semi-arid environment.

The effects of the planting density of the seed potato crop, the date on which it was defoliated and the time at which it was lifted, on the weight, shape and number of eyes on progeny tubers in a given size grade, were small and were unlikely to be of practical importance.

Size grade was both closely and linearly related to the number of eyes on a tuber and seemed to be a perfectly adequate practical method of grading seed tubers according to their number of eyes.

Field experiments were made in the rainforest zone of Western Nigeria over three cropping seasons on the effects of potassium fertilizer of one local cassava cultivar 53101 and two improved cultivars 60506 and 60447 which were F1 hybrids of the former. The results showed that K-fertilizer increased the starch yields only slightly. Cultivar 60506 produced significantly higher starch yields (P < 0–01) than the local strain, 53101, while cultivar 60447 gave lower starch recovery than the local cultivar.

A definite influence of K application on the cyanide (HCN) content of the tuber roots could not be established. The peeled tubers of the improved cultivars contained much less cyanide than those of the local 53101 strain (P < 0–01). Potassium had the highest (0·72–1·28% dry weight basis) while phosphorus had the lowest concentration (0·06–0·12%) in the peeled tuber. Owing to its higher yielding capability the unfertilized 60506 removed larger amounts of potash (average 110·9 kg k20/ha) from the soil than unfertilized 53101 (average 82·2 kg k20/ha).

Field experiments were made under irrigated semi-arid conditions to determine the effects of sowing date and nitrogen application on the growth and yield of wheat and nitrogen-uptake by wheat plants. Early sowing was found to be favourable to high grain production because the post-anthesis period coincided with relatively lower temperatures. Late sowing was unfavourable to grain yields since the period between anthesis and leaf senescence was curtailed by the onset of relatively higher temperature. The benefits from nitrogen were greater with early sowing because of higher nitrogen-uptake during early vegetative growth as a consequence of which, nitrogen was readily available to the plants. This resulted in better leaf expansion, and higher leaf-area indices and leaf-area duration. With late sowing nitrogen-uptake was much lower during early vegetative growth and this resulted in decreased leaf expansion, reduced leaf-area indices and leaf-area duration and therefore diminished response in grain yield to nitrogen application.

Forty-two Awassi lambs, 21 males and 21 females, were used to investigate the effect of early shearing, before the hottest months, on their performance and heat tolerance as indicated by rectal temperature and respiration rate.

Within each sex, half the number of lambs were sheared and the rest were left unshorn. All lambs were fed for 132 days, covering the hottest period of the year, on a concentrate mixture at the daily rate of 2% of their average live weight plus green roughage offered ad libitum. Rectal temperatures and respiration rates were recorded 1 day of each week on three occasions each day.

Shorn lambs of both sexes had significantly (P < 0·01) higher values for body gain and final body weight than the unshorn ones. Average total digestible nutrients intake was slightly higher for shorn lambs. However, average dry-matter intake as a percentage of body weight was almost the same for shorn and unshorn lambs. Shorn lambs of both sexes were more efficient than the unshorn ones in converting food to body gain.

Shorn lambs were more heat-tolerant than the unshorn ones as indicated by their significantly (P < 0·01) lower rectal temperature and respiration rate.

Blood samples were taken each week from 30 individually-reared heifer calves between 1 and 13 weeks of age and analysed for packed cell volume, blood glucose and Hb; and serum albumin, urea-nitrogen, total protein, inorganic phosphate, Ca, Mg, K, Na, Fe and total iron-binding capacity. All calves were weaned by 6 weeks of age, and were fed ad libitum.

There were significant changes (P < 0·001) in blood concentrations with age for most constituents. Concentrations of albumin and Fe increased and of K decreased steadily over the whole of the period. Glucose and total iron-binding capacity concentrations decreased until about the 6th week of life and then increased.

There were significant correlations (P < 0·05) for both the calves' weight gain and their feed intake from 6 to 13 weeks with the mean concentrations of glucose, inorganic phosphate, Na, albumin and total iron-binding capacity over the same period. Weight gain during this period was also correlated with serum Fe concentration. When weight gains were adjusted for the feed intake, the correlations between weight gain and the concentrations of all blood constituents became insignificant.

There was a significant correlation (P < 0·05) between weight gain after 6 weeks of age and Hb concentration before 6 weeks. However, when weight gain was adjusted for birth weight, this correlation became insignificant.

Marked significant differences were found between the crossbreed means in the percentages of palmitoleic, stearic, octadecenoic and the ratio of palmitoleic to stearic acids and in the percentages of subcutaneous, intramuscular and internal fats.

The percentage of carcass fats and age were strongly correlated with the acids palmitoleic, stearic (negative), octadecenoic and the ratio of palmitoleic to stearic. Covariance adjustment for percentage carcass fat and age made little difference to the significant differences of the variates which indicates that significant breed differences exist between these variates.

Mature Romney wethers with rumen cannulae and re-entrant cannulae in the proximal duodenum were fed a basal diet of silage with supplements of formaldehydetreated casein (protein) and starch/sucrose (energy). In addition methionine availability was increased by infusion of L-methionine into the duodenum.

Maximum intake was limited to near-maintenance with the aim of comparing treatment effects at the same level of intake. In practice, intake of the control silage alone decreased markedly after 10 days of feeding. This decline was significantly (P &0·01) reduced on the protein and energy supplemented diets, and intake increased again during the period of methionine infusion.

Protein and energy supplementation increased the flow of total N (P < 0·01) into the duodenum on the control silage and the flow of amino acids into the duodenum was increased from 50 g/day on the basal diet, to 77 g/day on the energy-supplemented diet, and 111 g/day on the protein-supplemented diet.

The percentage of amino acid N in the total N entering the duodenum was also increased by supplementation: from 72% on the control to 81% with energy supplement and 94% with protein supplement.

Comparisons of the amino acid composition of duodenal digesta indicated that a substantial part of the increased duodenal protein flow on protein-supplemented silage was due to the formaldehyde-casein being protected from degradation within the rumen.

The flow of amino acids into the duodenum was found to be closely related to amino acid intake, such that 67% of the variation in duodenal amino acid flow was associated with variation in intake.