The Hennessy and Chong Fat Depth Indicator and the Ulster Probe automatic recording instruments developed for measuring fat thickness were tested against the optical probe for use in pig carcass classification and grading.

Fat thickness measurements were taken using each probe 60 mm from the dorsal mid-line over the m. longissimus at the positions of the 3rd/4th lumbar vertebrae, 3rd/4th last ribs and last rib on a total of 110 hot carcasses covering the range of market weights in Great Britain. The standard deviation of carcass lean proportion at equal carcass weight was 35·4 g/kg.

The instruments differed little in the precision of carcass lean proportion prediction: residual standard deviation (g/kg) for the multiple regression with carcass weight and the best individual fat measurement for each probe were: last rib optical probe, 22·1; last rib Ulster Probe, 22·7; and 3rd/4th last rib Fat Depth Indicator, 21/6. Residual standard deviation (g/kg) for carcass lean proportion prediction from carcass weight and all three fat measurements in multiple regression were 21·3 optical probe, 21·3 Ulster Probe and 201 Fat Depth Indicator.

Similar mean fat measurements were obtained from the optical probe and Fat Depth Indicator, and for these instruments, but to a lesser extent for the Ulster Probe, the regression relationships with each other and with fat thickness measurements taken on the cut surface of the cold carcass were also similar.

The differences recorded in precision are unlikely to be sufficiently important to influence the choice of one probe rather than another.

Twenty sows and their litters were observed at regular intervals over the 1st week post partum to determine piglet-teat relationships. At 7 days of age, three piglets were exchanged between five pairs of litters, the other 10 litters remaining intact as controls. Observations of sucking were continued for another week. All piglets were weighed at 3, 7 and 14 days of age. Cross-fostering disrupted the teat sucking relationships of the whole litter compared with those of control litters, but the probability of sucking at the same teat in the 2nd week as in the 1st was less in fostered piglets than in their non-fostered littermates. The weight gain of fostered piglets during the 2nd week was reduced to 79% of that in their non-fostered littermates. Both disruption of sucking and reduction in weight gain were greater in those piglets that had to compete, on their foster mother, for the teat they preferred during the 1st week than for those whose teat was free.

The behaviour of eight litters of Large White × Landrace piglets aged 3 weeks was scored in flat-deck cages every 2min for 12 h during the day, noting the frequences of 11 behaviour patterns. Similar observations were made at 6 weeks of age, and five main activities at the two ages were compared. There was a significant decrease in the frequency of aggressive encounters between the two ages, while the other activities remained at the same frequencies. The proportion of scores devoted to the main activities is given.

Groups of pigs were observed from weaning to marketing for the incidence of tail and/or ear biting and persistent inguinal nose thrusting. The 16 groups included single and mixed litters, single or mixed-sex ratios, and comprised up to 12 pigs; 14 of the groups showed biting behaviour and 12 groups showed persistent inguinal nose thrusting behaviour. The onset of biting appeared from 0 to 44 days after weaning, and persistent inguinal nose thrusting was first observed 4 to 22 days after weaning.

There was a significant relationship between the number of pigs biting and being bitten in a group. The high ranks tend to bite middle and low ranks more than expected, the middle ranks bite other middle ranks more than expected, and low ranks bite the least. Within any rank there was no difference between male and females biting or being bitten. The most common situation was to have, in a group, some pigs which only tail bit, others that only ear bit, and others which both tail and ear bit. It is suggested that biting is a learned response spread by visual communication, so that visual barriers around affected groups may help to limit the spread of an outbreak.

In persistent inguinal nose thrusting behaviour, rank was important, as the top ranking pigs were the most most likely to show persistent inguinal nose thrusting. Persistent inguinal nose thrusting may have its origin in udder seeking, exploratory or rooting behaviour, but becomes used mainly by dominant pigs. The behaviour is halted by the pig which received the nose thrusts moving away.

Pigs weaned at 2 days of age were given a milk substitute until 28 days of age containing either 10 or 52 fig biotin per kg dry matter. During the last week of the experiment a slight deterioration in the ratio of feed: gain (0·1 > P > 0·05), but not in weight gain, was found in pigs given the low-biotin diet. No signs of biotin deficiency were observed, but pigs given the low-biotin diet had lower concentrations of biotin in the liver and carcass. Most of the biotin was in the liver. These results suggest that 10 fig biotin per kg dry matter may be adequate for pigs until at least 28 days of age.

Forty-eight castrate male and female Suffolk cross Mule lambs were used in a 2 × 2 factorial experiment to investigate the effect of autumn shearing and sex on growth performance over 46 days before slaughter. Lambs were penned individually outdoors and given pelleted lucerne ad libitum.

Shearing increased average food intake by 0·072 (P<0·05), live-weight gain by 0·149 (P<0·01) and carcass weight by 0·058 (P<0·05). It is concluded that shearing is financially worthwhile in climatic conditions such as the present experiment.

ANIMAL PRODUCTION, Volume 33, Part 1, pp. 81-86

COPPER SUPPLEMENTATION OF ISONITROGENOUS DIETS FOR GROWING PIGS CONTAINING WHITE-FISH MEAL OR SOYA BEAN MEAL AS THE PROTEIN SUPPLEMENT