Hens and cockerels of a White Leghorn strain (‘H & N’) were kept at a constant temperature of 23 °C from 1 year until 2¼ years of age. The mean fasting heat production, which was measured 6 times during this period, varied between 404 and 464 kJ/kg0·75/day for the hens and between 223 and 349 kJ/kg0·75/day for the cockerels. The sex difference in heat production is discussed and an attempt is made to explain the variation in heat production for each sex.

The heat production of hens and cockerels of a White Leghorn strain (‘H & N’) was measured after acclimation to environmental temperatures of 16, 23, 27 and 33 °C. No difference in fasting heat production was found between 16 and 23 °C for well-feathered hens in the first few months after moult though there were substantial reductions at 27 °C and above. Both hens and cockerels showed a trend of increasing net availability of metabolizable energy with increasing environmental temperature though this was non-significant. There were significant reductions between 16 and 27 °C in the metabolizable energy requirements for maintenance for both sexes.

Results are also given for the heat production of laying hens exposed to short daylight periods and high or low environmental temperatures. Although the mean fasting heat production of the high-temperature group was greater, the difference was not statistically significant.

Distribution of red cell potassium in buffaloes and its possible genetic control was investigated. The mean values of red cell K+ varied between 37 and 41 m-equiv/l in LK type animals and between 87 and 91 m-equiv/l in the HK type. Red cell K+ concentration within individual animals of either LK or HK type was fairly stable over successive samplings, whereas the same values among animals within a type varied rather widely. The inheritance of red cell K+ type in buffaloes appeared to be controlled by a single pair of genes. HK animals were homozygous for the recessive allele while LK animals represented the heterozygotes and also the homozygotes for the other allele. In addition, there was indication that the gene responsible for LK phenotypes might not be completely dominant over the recessive allele. The three populations of buffaloes examined were found to be in genetic equilibrium in respect of red cell K+ polymorphism. HK animals predominated in both the breeds, the frequency of the recessive gene (h) being 0·78 and 0·74 for the Murrah and Bhadawari breeds respectively.

The possible adaptive significance of the occurrence of HK and LK red-cell types in Murrah buffaloes was investigated. Judged by haematological indices and thermorespiratory responses under conditions of moderate thermal stress, LK animals appeared to have a greater adaptive potential than HK animals in a hot arid environment. Dry matter percentage, packed cell volume (pcv), haemoglobin concentration (Hb), red blood corpuscles (RBC) and plasma protein values were significantly higher in LK-type animals. In addition, under identical conditions of thermal stress the LK animals exhibited significantly less rise in rectal temperature and respiratory rate than the HK animals.

Two field experiments were conducted in 1971–72 and 1972–73 on two similar sites of calcareous clay soils (vertisol) with paste pH 8·2, 0·024% and 0·22% organic carbon. Wheat (Triticum aestivum L. var. (LR N10) An3) was grown and the fertilizers ammonium sulphate, urea, nitrophoska 15% N, 15% P2O5, 6% K2O), calcium nitrate (Ca NO3)2·4H2O) and ammonium sulphate nitrate were each used at 70 kg N/ha at seeding, tillering, jointing or ear emergence and there was one treatment with no N fertilizer. The treatments were arranged in a randomized block design with four replications. Each plot was 6·0 x 7·0 m of which 4·0 x 5·0 m was harvested. N fertilizers were broadcast by hand and no basal potassium or phosphorus were added since they are known to have no effect on wheat yield on these soils. Seed a rate equivalent to 85 kg/ha was weighed separately for each plot and sown by hand in rows spaced 20 cm apart. Each experiment received 10 irrigations, each equivalent to a head of 10 cm of water, at 10-day intervals.

The gross energy of forages can be classified into three fractions, namely the unavailable fraction, the digestible energy fraction and the potentially digestible energy (PDE) fraction. The PDE fraction can only be made available by appropriate treatment and supplementation (Pigden & Heaney, 1969). In young forages the PDE fraction is relatively insignificant, but as the plant matures, the PDE fraction increases very rapidly. By treating matured forages with delignifying agents, increased nutrient digestibilities have been demonstrated Chandra & Jackson, 1971; Wilson & Pigden, 1964), but no significant improvement on the voluntary intake was achieved unless the treated material was supplemented with a source of nitrogen (Donefer, Adeleye & Jones, 1969). While Zafren (1960) used ammonium hydroxide (NH40H) as the treatment alkali, with the claim that the ammonium acetate resulting from the neutralization of the excess alkali could serve as an extra source of nitrogen in the treated straw, other investigators (Donefer et al. 1969) have adopted the method of supplementing the treated straw with a source of nitrogen. Since the efficiency with which dietary nitrogen is converted to microbial nitrogen in the rumen has a considerable influence on the efficiency the animal as a whole, studies herein reported were carried out to test the effectiveness with which rumen micro-organisms utilize different nitrogen sources in degrading cellulose in vitro.