From the published data summarised in Table 1, it was calculated that, at an average degree of feed restriction of 15·8 %, daily weight gain decreased by 12·50% (or 0·78% for each 1% restriction), feed conversion efficiency improved by 3·96% (or 0·31% for each 1% restriction) and backfat thickness diminished by 7·63% (or 0·53% for each 1% restriction).Equations were calculated to show the degree to which daily weight gain, feed conversion efficiency and backfat thickness change with increasing feed restriction (Figures 1, 2 and 3).As the degree of feed restriction increases, the decrease in daily weight gain becomes relatively greater and the decrease in backfat thickness relatively smaller. Efficiency of feed utilisation, however, improves at first, but eventually decreases as restriction becomes more severe.It is thought that the equations found can be used, within certain limits, to calculate the average effects of feed restriction for different breeds of pigs, which when fed ad libitum consume 2·7 kg. meal ration (of normal composition) per day and have a growth rate of about 750 g. daily from 30 to 90 kg., and backfat thickness of about 37 mm. when kept under average environmental conditions.

A study, based on data from the literature, was carried out to establish the quantitative effect of increasing levels of various fats on food intake, weight gain and efficiency of food conversion of growing chicks.The fats concerned were soyabean oil, soyabean soapstock, maize oil, lard, grease and tallow. Their effect was studied by using regression analyses.It was found that the addition of fat, both animal fats and vegetable oils, diminishes food intake. The food intake decreases significantly with rising percentages of fat according to a linear function. No differences in effect between various fats could be demonstrated.The incorporation of various fats improves the weight gain, although the increase was not related to the amount of fat added. The improvement in weight gain differs from one fat to an other.The addition of fats improves efficiency of food conversion, but varies according to the kind of fat. Here the improvement is correlated with the level of fat added.The difference in improvement of food conversion can be only partially explained by differences in absorbability and metabolisable energy of the fats.It is concluded that certain fats ameliorate the efficiency of food conversion and, in some cases, weight gain to a higher degree as may be expected from their metabolisable energy content. It might be possible that some fats possess one or more factors which improve the efficiency of metabolisable energy or exert a protein anabolic action.

The relation between milk ejection and antidiuretic response was studied on lactating cows using different stimuli.The stimuli, utilized to induce milk ejection, could be classified according to increasing effectiveness as follows: (1) showing the calf to the mother (visual stimulation); (2) washing the udder with water at 40\ s=deg\ C in trained animals; (3) washing combined with visual stimulation; (4) suckling. Experimental conditions (hydration, bladder catheter) exerted a marked inhibiting effect in most animals on the milk-ejecting reflex induced by stimuli 1, 2 and 3. The reactions of domesticated cows under these circumstances are analogous to those of primitive breeds under normal conditions. Generally, the antidiuretic response seemed to be quantitatively correlated with the release of oxytocin. However, exceptions to this rule were observed.An antidiuretic response was obtained in cows after milk ejection unaccompanied by withdrawal of milk.The effect of known amounts of oxytocin on milk ejection was studied, and the dose-response curve was nearly a straight line when log dose was plotted against the volume of milk ejected. The slope of the curves, however, varied in different cows.A pituitary type of antidiuretic effect in connexion with milk ejection has been observed in several species: not occur in all cases of milk ejection and quantitatively high variability is observed. Since this phenomenon relates to the mechanism of release of the posterior pituitary hormones, we have studied the effect of various stimuli and the quantitative relation between milk ejection and antidiuresis on the lactating cow. Cross [1951] studied suckling antidiuresis in the lactating rabbit. He obtained evidence suggesting that removal of milk from the mammary glands may be necessary for the appearance of an antidiuretic response to suckling. It is possible, therefore, that, while stimulation of the teats alone is sufficient to evoke release of milk-ejection hormone, passage of milk out of the glands is required to excite the additional release of antidiuretic hormone (ADH). As cows can be trained to 'let down ' in response to massage of the teats with a warm udder cloth before actual milking is commenced, Cross [1951] suggested that it would be interesting to see if such a procedure resulted in antidiuresis.

SUMMARYFour litters each containing six female pigs were used to compare the influence of the level of feeding of suckled pigs on subsequent weight gain and efficiency of feed conversion, and on carcass quality and ham composition.The high level pigs always remained on their dam until weaning at 56 days of age and had free access to a starter ration from the beginning of the 4th week of age. From 7 days of age until weaning the low plane pigs were removed from their dam for 12 hours per day and had no access to starter ration during this time. After weaning the pigs were fed ad libitum on dry feed.It was found that live-weight gain and feed conversion efficiency during fattening were increased by lowering the feed intake of pigs in the first weeks of life. There were no statistically significant differences between the different butcher's joints of the two groups. Although the differences were statistically non-significant, the ham of the low level pigs had a higher protein content (P = 0·06), a higher water content (P = 0·10), a lower fat content (P = 0·07) and a lower energy content (P = 0·12).

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