Experiments were carried out with Clun Forest ewes to determine the effect on the onset of oestrus of applying the same abrupt decrease in daylength at two different times of the year. An abrupt decrease in daylength of 3·75 hr was applied to the ewes on 1 July 1968 and on 24 April 1969. The mean number of days from the commencement of the light treatment to the onset of oestrous activity was 59·5 and 87·0 days, respectively. It is concluded that the time of year at which the light treatments were applied, or the previous light treatment of the Clun Forest ewes, or both, significantly (P<0·001) affected the date of onset of oestrus.

1. An experiment was conducted in which the effects on growth rate, food conversion efficiency, digestibility and rate of passage through the gut of diets containing 85% of differently processed barley, fed to growing pigs, were studied. Five different processing treatments were compared with the inclusion of the grain in the whole (unground) form (diet W). The processing treatments were: grinding through (1·56 mm), (4·68 mm) and (9·36 mm) screens (diets O, T and S respectively); cold rolling (diet R) and coarse crimping (diet C).

2. Differences in growth rate and food conversion efficiency between diets O, T, S and R were small and not significant with a slight overall superiority evidenced for diet R over the other three. Compared with these results those of diets C and W were inferior, significantly so for both diets in growth rate but for diet W only in food conversion efficiency. Diet C was superior to diet W in both of these parameters (significantly so for growth rate).

3. The overall digestibility of diet W was significantly poorer and the rate of passage through the gut faster than for any of the other diets. Diet O was retained in the gut significantly longer than any of the other diets and gave the highest coefficient of apparent digestibility for both the ether extract and crude fibre fractions of the diet.

The effects of giving starch and sulphur, and of the frequency of administration of urea, were measured in N balance experiments with two Rahmany rams. Urea N utilization was greatly improved by dividing a single daily dose into three equal parts. Starch and sulphur also improved the utilization of urea N.

The relation between the weight of the alimentary tract contents and the weights of body fat and the uterus was examined in 23 Blackface ewes. Six ewes were not pregnant, five had single foetuses and 12 had twins. The pregnant ewes were slaughtered three or four days before their expected lambing date. There was a negative relation between uterine weight or body fat weight and the weight of alimentary tract contents. The effect of uterine weight was small and not significant when only the pregnant animals were considered. It was unlikely that physical restriction of the alimentary tract by the uterus played more than a minor role in limiting voluntary food intake under the conditions of this experiment.

On a hill farm, 376 Scottish Blackface ewes with all permanent incisor teeth present (whole mouth) at 53 months of age were compared with 118 ewes having one or more of these teeth missing (broken mouth). By 46 months, ewes becoming or already broken-mouthed were significantly lighter in weight and although at their third lambing they gave birth to the same number and weights of lambs as whole-mouthed ewes, their twin lambs were significantly lighter in weight from about three weeks of age onward. At their fourth lambing, broken-mouthed ewes produced and reared significantly fewer lambs and of lighter weight than their whole-mouthed contemporaries. Grazing of turnips increased the incidence of ewes with broken mouths.

The litter size and lambing rate of 1531 ewes of British hill breeds which had been mated to Finnish Landrace or Border Leicester rams was found to be independent of breed of ram. It was concluded that Finnish Landrace rams do not have a particular effect on the reproductive performance of ewes to which they are mated.

The daily voluntary food consumption (VFC), water intake and urinary excretion of water, sodium and potassium of eight sheep were studied before and after shearing. The extracellular volume of each sheep was measured twice before and three times after shearing. VFC was significantly higher for the first 3 weeks after shearing than for the 3 weeks immediately before shearing. There was a decreased excretion of Na in the urine and a smaller Na/K ratio for the first 2 weeks after shearing, although the extracellular volume was not significantly increased until 4 weeks after shearing. Within, but not between, the 3-week periods before and after shearing, there was a close linear relationship between VFC and water intake, the latter being significantly less for the same VFC after shearing. During weeks 4 and 5 after shearing, there was an increased loss of Na in the urine and a higher Na/K ratio, and the linear relationship between VFC and water intake was intermediate between that shown before and after shearing. The VFC of the sheep before shearing and in week 5 after shearing were similar.

1. In vivo gastric pH changes were studied, in 6 pigs fitted with permanent gastric cannulae, under ‘basal conditions’ (i.e. when no food was given) and when diets containing 85% of differently processed barley were given either twice daily or at frequent intervals of time in an attempt to simulate ad libitum feeding systems. Before inclusion in the diet the 85% of barley had either received no processing (i.e. was given as the whole grain) or had been processed in one of the five following ways: (a) ground through a (1·56 mm) screen (b) ground through a (4·68 mm) screen (c) ground through a (9·36 mm) screen (d) coarsely crimped (e) cold rolled.

2. Relative to the ‘basal’ determinations the systems of feeding which gave food at frequent intervals of time induced higher overall mean pH values than did those which gave food twice daily, while between the six differently processed diets those containing the smaller particles of barley tended to give higher overall mean pH values than did those containing the coarser particles.

3. The validity of the results is discussed in the context of the techniques used and some possible implications in terms of animal health are briefly discussed.

Mating trials were conducted to test the fertility of rams having a range of scrotal wool cover. These revealed that rams with heavier scrotal wool cover had reduced fertility in comparison with those having lighter scrotal wool cover.

Animal Production: Volume 12, part 1, pp. 55–62: A number of arithmetical errors have been found in the paper entitled: The incidence, Repeatability and effect on dam performance of twinning in british friesian cattle

An estimate of the frequency of twin calvings was obtained from the analysis of over 38 000 calvings of Friesian cows in M.M.B, milkrecorded herds. The incidence of twinning increased from 0·54% in the first parity to 3·37 % in the fifth parity. A significant excess of cows above expected produced either more than one set of twins or no twins at all. Repeatability ranged from 0·028 for cows with three calvings to 0·063 for cows with five calvings.

Data on lactation yield and duration, butterfat percentage and calving interval showed some significant effects of twinning. Consistent trends were noted showing that dams which calve twins have longer subsequent lactations, higher whole lactation yields and lower fat percentages than contemporary dams with single calves. The possible causes for these trends are discussed and are considered to be the lower breeding efficiency and longer calving intervals of dams of twins.

Identical group-feeding experiments (each of 90 days duration) were conducted in the summer and in the winter of 1968. The purpose was to study the feed-lot performance of the Grey Shirazi breed on high- and low-concentrate diets with or without diethylstilboestrol (DES) in two different seasons of the year. Lambs on the high-concentrate diet gained more than those on the low-concentrate diet both in summer and in winter. On both diets lambs performed better under cold than under warm conditions. There was no difference when DES was given orally with the above two rations.

Studies of the social behaviour of a hill flock of sheep confirmed the existence of home range groups with each group having a definable territory. The groupings were not broken by a period of individual penning of the sheep.

Fertility of rams was studied following their exposure to heat for 1 or 3 days in a hot room. Eight to 16 days later exposed rams showed significantly lower fertility as judged by lambing rate of ewes compared with unheated control rams. From 25 to 36 days after exposure treated rams were not significantly less fertile than controls. There were no significant differences in fertility between rams exposed 1 day or 3 days to heat.

The nutritional value of dried poultry excreta was investigated by determining the apparent digestibility of dry matter, organic matter, nitrogen, energy and copper in five diets containing 0 to 100% of this feed. Dried poultry excreta supplied 20·21% apparently digestible crude protein and approximately 1·57 or 1·74 Mcal of metabolizable energy per kg dry matter.

The copper in dried poultry excreta was found to be less digestible than the copper in barley. It is concluded that, as far as copper levels are concerned, dried poultry excreta are safe for ruminants, and are a source ofcheap protein. More detailed work is needed to determine the metabolizable energy of the material accurately.

In two trials 20 female pigs were given diets containing up to 50 p.p.m. ‘Bitrex’ during their growth from 100 to 200 lb live weight. Voluntary feed intake, daily live-weight gain and carcass quality were not influenced significantly.

Groups of Clun Forest ewes, in which oestrus had been synchronized following the removal of progestogen-impregnated pessaries, were introduced into a small enclosure containing tethered Hampshire, Suffolk and Clun rams. The ewes exhibited a clear preference for the ram of their own breed. The Suffolk ram appeared to be a very poor second choice. When the Clun ram was replaced by a Kerry more ewes went to the Suffolk than to either the Hampshire or the Kerry. When Clun ewes were introduced to 3 tethered Clun rams there was no obvious preference for an individual ram.