Live weights of 8764 calves born in seven herds in Cuba during the years 1966–8 were measured at birth and at approximately 3 months of age. Over 2600 were pure bred: Zebu (2002), Santa Gertrudis (435) and Charolais (212); the remainder were crossbred Holstein x Zebu (4955) and Brown Swiss x Zebu (1160).

Year, season of birth, herd and sex were associated with variation in mean birth weight in all breeds and crosses except Charolais in which no seasonal effect was apparent and in Brown Swiss x Zebu cross-breeds in which herd and sex effects were absent.

At 90 days there was a general tendency for calves born in late spring and summer to be heavier than those bom at other times. By this age, herd variation had subsided among Brown Swiss x Zebu cross-breds, and variation due to sex had ceased to be important among Charolais calves.

Estimates of heritability of birth weight ranged from 0·09 in Holstein crosses to 0·62 in Brown Swiss crosses, and of weight at 90 days from 0·05 in Brown Swiss crosses to 0·44 in the Charolais breed. Phenotypic correlations between birth and 90 days weights were of the order of + 0·25 while genetic correlations were positive for pure breeds and negative for cross-breeds.

Four hundred and fifteen oocytes cultured in growth medium for 24·5–28·5 h were transferred to the oviducts of 23 oestrous ewes. Twenty ewes were bred prior to transfer; three remained unbred as a control. After intervals of 24–73 h oocytes were recovered. In 179 oocytes from 19 bred recipients, 19 pronucleateand 26 cleaved eggs were recovered; one apparent 4-cell egg was found in 37 oocytes recovered from unbred ewes.

The authors regret the following errors: Page 102, Appendix Table 1, lines 13, 15, 17, 20 and 22 of the Table should be amended as follows:

Réunion Island, situated in the Indian Ocean, presents a unique case study for modelling regional bio-economic parameters of the dairy industry. It is a good example of a closed system for several parameters of the model such as movement of animals, labour, consumption and available land. The existence of several agro-ecological zones from tropical to temperate, and various different types of terrain and vegetation presents another unique opportunity to study the impact of these features on the dairy industry. The present study models the dairy sector at a regional (island) level to study the impact of new or adapted agricultural policies in relation to changes in subsidy levels, price fluctuations and environmental policies (mainly nitrogen management). The model can be used to generate a number of scenarios to explore the effects of various policy measures, such as fixing the stocking rate according to EU norms, increasing or decreasing the milk subsidy, intensification (such as an increase in milk production to the allotted quota of 40 million litres/yr) and varying labour/price constraints (such as a reduction in labour hours or an increase or decrease in the milk price). The model is being utilized by the local dairy cooperative as a discussion support tool to study the implications at the regional scale of expanding the sector and assessing its economic, environmental and social impact.

1. The daily retention of calcium, carbonate, phosphorus and chloride was studied using four birds and changing the calcium carbonate content of the ration every 5 days for 15 days.

2. It was shown that high calcium diets result in a much lower retention of calcium and thin-shelled eggs are produced.

3. Retention of calcium was higher in the laying than in the non-laying bird when calcium carbonate was fed.

4. High calcium diets depressed the retention of phosphorus, and in one case the retention was negative, even when no eggs were laid. Laying birds gave negative values for retention because of the heavy phosphorus excretion associated with egg laying.

5. High calcium diets also depressed the retention of chloride, and on occasion led to negative retention values.

This material which is also known as distillery dregs, dried dreg or slummage is a by-product of the production of alcohol. In this process a mixture of coarsely ground cereals is used and, after fermentation, the liquid extract is drawn off leaving behind the distillers’ grains or draff.

The reproductive performance of 253 female Romney sheep of different ages has been studied from 1958 to 1960. Comparisons of the reproductive performance were made between ewes grazed on red clover pastures and ewes grazed on perennial rye-grass and white clover swards. The red clovers were oestrogenic during all periods of utilization.

The ingestion of oestrogenic red clovers caused the ewe lambs to accept the male before the start of the normal breeding season. No corpus luteum was found in the ovary of these lambs thus induced into oestrus. The subsequent reproductive performance of these ewe lambs at 2 years of age was not affected. The oestrus per se or the regularity of oestrus of the young (1½-year-old) or the aged (5½-year-old) ewes was not affected by the diet of oestrogenic red clover.

The ingestion of oestrogenic red clover did not affect the reproductive performance of the young ewes at 2 years of age, but did cause a protracted lambing season and a reduced level of lambing performance in the aged ewes at 6 years of age. No endometrial cyst was found in the aged ewes. It was suggested that the reduced level of reproductive performance of the aged ewes could have resulted from an unfavourable environment within the ewe, for the process of fertilization or implantation of the fertilized ova during the breeding season.

The gas production in batch fermentation of vegetable matter found on farms is shown to lend itself to the application of monomolecular equations providing an active and well-developed starter material is used for initiating the fermentations. The reaction velocity constants as established for a common material found in the tropics, namely elephant grass, would seem to be some two to five times lower than that previously reported for sewage sludge. The higher rate of decomposition of the sewage sludge is attributed to its more favourable physical condition and possibly also to its greater content of more easily fermentable substances.

Cluster analysis has been commonly used in genotype-by-environment (G×E) analyses, but current methods are inadequate when the data matrix is incomplete. This paper proposes a new method, referred to as two-stage clustering, which relies on a partitioning of squared Euclidean distance into two independent components, the G×E interaction and the genotype main effect. These components are used in the first and second stages of clustering respectively. Two-stage clustering forms the basis for imputing missing values in the G×E matrix, so that a more complete data array is available for other G×E analyses. Imputation for a given genotype uses information from genotypes with similar interaction profiles. This imputation method is shown to improve on an existing nearest cluster method that confounds the G×E interaction and the genotype main effect.

Organic manures, despite their low nutrient analysis, play a significant role in meeting fertilizer needs of crops. When manures are applied in conjunction with fertilizers, yields are generally higher than with equivalent fertilizers alone. An increase in the yield optima leads to uncertainties in working out fertilizer economy in quantitative terms. In order to overcome this, a concept of fixed yield is described in this paper.

1. Certain carcass measurements (length, shoulder and mid-back fats, belly thickness and dressing percentage) made on a total of 402 bacon pigs from four antibiotic feeding trials have been analysed.

2. The length of the carcasses showed more variation between pens treated with various doses of penicillin than between control pens or pens treated with aureomycin. This greater variation in length was related to the greater variation in growth rate between the penicillin treatments. No differences in the mean lengths of control, penicillin and aureomycin treatments were found.

3. Back fat measurements and belly thickness showed no differences between aureomycin, penicillin and control treatments in overall tests.

4. Aureomycin consistently gave higher dressing percentages than penicillin. Animal protein also gave higher dressing percentages than vegetable protein, but no effect of vitamin B12 on this quantity was found.

Two experiments were carried out in order to study the effect of the ash content of poultry litter (PL) on its nutritional value. In Expt 1, broiler PL was incorporated in the proportions of 30 and 45% into diets based on wheat straw supplemented with 20% maize grain. The PL was either fresh (containing 19% ash) or had been heated in a stack (giving 26% ash). There were also two additional diets containing 45% fresh PL to which either ground limestone or wood ash had been added to provide the same ash content as the diets containing 45% stored, high ash PL. An in vivo digestibility and nitrogen balance trial was carried out. Storing the PL, which resulted in heating and an increase in ash content, reduced dry matter intake significantly. The largest and most significant effect on the digestibility of dry matter, organic matter and crude protein can be ascribed to the freshness of the PL. Stored, heated PL had a highly negative effect on crude protein digestibility and on nitrogen retention. No negative effect of adding extrinsic ash was recorded. In Expt 2, the nutritional value of layer PL (LPL), compared with that of broiler PL (BPL), was examined using ten beef cows before and after calving. The diet was composed of 45% PL, 35% wheat straw (WS) and 20% maize grain. Daily dry matter intakes were 12·7 and 16·2 g/kg liveweight (LW) before calving and 15·5 and 22·8 g/kg LW after calving, for cows fed LPL and BPL, respectively. Owing to the combined effect of the lower dry matter intake, lower gross energy content and lower digestibility of LPL, the digestible energy intake of BPL diets was almost three-fold, and nitrogen absorption (g/kg LW0·75) on the BPL was 2·4-fold higher than on the LPL diets. Because the ash intake of both diets was similar, it is suggested that the main inhibiting factor of intake after calving was the rumen's ability to mobilize the large amounts of ash-rich complexes of ash and organic matter to the reticular omasal orifice and, consequently, out of the rumen.

A study is made of 46 years' records of rainfall for each of the months April to September. Following the determination of the distribution of monthly rainfall recommendations are made as to the best method of specifying rainfall and of predicting the rainfall to be expected on the basis of previous observations.

An examination of the population density and morphology of the apocrine glands of four ‘races’ including fourteen breeds of African indigenous cattle has been completed.

Two types of gland were found, the club-shaped and the sac-like, and it is suggested that the former is the more primitive form.

Considerable differences in gland density and volume were found. In the thoracic-humped African Zebu both of these were similar to figures given for B. indicus sui generis.

Gland volume was found to be closely correlated to heat toleration, but it is suggested that secretory rate is probably of high importance in view of the fact that despite differences in gland volume, there were only small differences in heat toleration coefficient.

It is suggested that the heat toleration coefficient as presently defined may not be a reliable indication of the animals tolerance of prolonged high temperatures.

A suggestion is made regarding the mechanism of heat control by sweating in cattle.

1. The effect of different levels of protein on the digestibility of the carbohydrate fraction of two compounded diets which differed widely in their contents of indigestible organic matter has been determined.

2. Digestibility of the available carbohydrate (the sugars, dextrins and starches expressed as starch) apparently increased with increase in the protein content of the diet.

3. Alteration in the cereal portion of the diet involves an adjustment in the amount of protein supplement if the nutritive ratio is to remain unaltered.

An experiment to study the effect of sowing time (21 October, 5 November, 20 November, 5 December and 20 December), seed rate (5, 7·5 and 10 kg/ha) and application of nitrogen fertilizer (0, 20, 40 and 60 kg N/ha) was conducted at the Punjab Agricultural University, Ludhiana, on a loamy sand soil during the winter seasons of 1974–5 and 1975–6. The delay in sowing from 21 October to 20 December produced shorter plants with fewer spikes. The crop sown on 21 October using 7·5 or 10 kg seed/ha and supplied with 20 or 40 kg N/ha gave better yield than those of later sowings.

An examination has been made of the possibility of extending the routine mechanical analysis of soils down to finer particles than the conventional clay. The main conclusions reached are:

(1) Sampling depths of only 2 cm., using standard mechanical analysis apparatus, appear to introduce no new sources of error.

(2) If a constant temperature room is available, sampling times of 7 days seem to be allowable.

(3) Using special pipettes and settling vessels, sampling depths of only 2½ mm. seem to be allowable.

Thirty-seven lines from a population derived from the hull-less barley cultivar, Penthouse, were grown in a replicated trial over three seasons and assessed for grain yield. Following harvest, a rapid test to measure grain dimensions was applied to all samples, to look for novel variation in grain size and shape, as a possible way of detecting mutations. A range of grain and malt quality traits was also measured in two of the seasons, to detect genotype × season interactions and determine relationships between the measured traits. There were significant differences between years for all traits and between genotypes for most. Genotype × season interaction was significant for grain dimensions and some malting traits, but a correlation between malting quality and grain dimensions was only observed in one season. Line 30 showed very high yield potential in a comparatively wet season and gave a higher alcohol yield per unit area than a hulled control variety, while lines 21 and 33 contained putative additional mutations. Line 21, previously observed to have higher enzyme activity, appeared to contain an additional dwarfing gene and was characterized by smaller grain, later ear emergence and lower yield. Line 33, with malting potential, showed considerably altered grain length to width ratio and will be further investigated as a possible globosum type.