In order to determine the relative digestibilities of nitrogen and amino acids in foodstuffs for pigs and poultry, and the effects of manufacturing methods, equal quantities of soya-bean meal, sunflower meals [hulled (sunflower meal 1) and dehulled (sunflower meal 2)], meat meals [made with (meat meal 1), and without (meat meal 2), blood added at 250 g/kg meat tissue (wet weights)] and rapeseed meals [seeds heated at 80°C (rapeseed meal 1) or 100°C (rapeseed meal 2)] were mixed with protein-free ingredients. The diets were given to five growing pigs with ileo-rectal anastomoses, and, by crop-intubation, to 12 caecectomized and 12 intact cocks. Excreta were collected over 48-h periods. Endogenous excretion was estimated by giving protein-free diets.In the order, soya-bean meal, sunflower meals 1, and 2, meat meals 1, and 2, rapeseed meals 1, and 2, true digestibilities were: with pigs, of nitrogen, 0·81, 0·80, 0·79, 0·64, 0·79, 0·73, 0·70 (s.e.d. 0·030), of lysine, 0·84, 0·83, 0·84, 0·65, 0·84, 0·76, 0·72 (s.e.d. 0·032); with caecectomized birds, of nitrogen, 0·92, 0·91, 0·91, 0·66, 0·78, 0·74, 0·75 (s.e.d. 0·018), of lysine 0·92, 0·91, 0·93, 0·62, 0·79, 0·70, 0·70 (s.e.d. 0·020); with intact birds, values were similar to those with caecectomized birds for soya-bean, and the sunflower meals, but lesser for meat meals 1 and 2; the solubilities of nitrogen in pepsin were 0·96, 0·92, 0·93, 0·80, 0·89, 0·87, 0·87.Two hundred and eighty pigs (initial live weights 10 kg) were used to compare growth response to free lysine with that to lysine in soya-bean meal and sunflower meal 2. Lysine availabilities, assessed by analyses of regressions of live-weight gain against lysine intake were 0·82 (s.e. 0·12) for soya-bean meal, and 0·82 (s.e. 0·18) for sunflower meal 2.Amino acid digestibilities of the sunflower meals were similar to those of soya-bean meal, and were not influenced by dehulling; values for the rapeseed meals were lower, and unaffected by differences in heating severity; values for the meat meal were reduced by blood addition. Values differed between pigs and poultry, but there was consistency in the extent to which each species discriminated between some foodstuffs. The pepsin test was insensitive. The large standard errors associated with availability values prevented meaningful comparisons with digestibility values.

Vitamins are microelements which do not play a critical role in animal feed formulation, mainly because of their commercial availability in the synthetic form at relatively low prices (the cost of vitamin A in a feed supplemented to 10,000 IU/kg is about 30 centimes per 100 kg). Some cereal by-products, like bran, exhibit a high phytase activity, which may enhance phytic P digestibility. This was studied in growing pigs given phytate-rich diets containing either wheat-(WB) or rye (RB)-bran. Two trials involving 12 animals each (6 treated, 6 controls) were carried out, one (WB trial) with a 15 p. 100 fine WB diet and the other (RB trial), a 20 p. 100 fine RB diet and their respective controls (WC and RC). The four diets (WB, RB, WC and RC) contained the same amounts of energy, protein, Ca (0.7 p. 100) and P (0.4 p. 100) and no organic P was added. Pigs were fed these diets for 3 (WB trial) or 8 weeks (RB trial) during which 10-day balance studies were performed. Then animals were slaughtered and bone samples collected.WB, WC and RC, in contrast to RB-fed pigs developed a P-deficiency as indicated by hypophosphatemia, hypophosphaturia, hyperhydroxyprolynuria and hypercalcemia. P from RB diet was better adsorbed (55 p. 100) and retained than that of the control diet (36 p. 100), but this « bran effect » was absent with the WB diet (37 p. 100 for both WB and control diets). Ca adsorption was the same for all diets, but Ca was better retained in rye bran-fed than in corresponding controls. Pigs fed both, rye or wheat, bran diets showed a higher bone bending moment (BM) and density than controls, the greatest effect occurring with rye bran (tibial BM

containing 3.6 g lysine/1 000 kcal DE were compared. The control diet was based on wheat, soybean meal and mineral and vitamin mixture. Diets 2, 3 and 4 contained wheat (about 80 %), only 14.8 % soybean meal and were supplemented with 0.53 % lysine HCI, 0.07 % methionine and 0, 0.10 and 0.20 % threonine. The four diets contained 23.8, 18.3, 18.2, 17.7 In trial D, a control diet (T) containing 0.16 % methionine and 0.15 % cystine was compared to a diet TM (T + 0.08 % DL-methionine) and a diet TC (T + 0.08 % L-cystine). The trial was made in piglets weighing initially 10 kg fed ad libitum for 21 days. Methionine supplementation significantly improved performance. Cystine supplementation neither improved weight gain nor feed conversion ratio and decreased feed intake. It was concluded that methionine should represent at least 55 % of sulphur amino acid supply. Dietary calcium excess may decrease phytic P digestibility in hamsters and rats and bone breaking strength in pigs. An experiment was made to compare Ca and P balances, mineral content, density and bending moment of bones in pigs fed either a high (1.4 %) or a normal (0.6 %) Ca diet for 2 months. No inorganic P was added and the total P (0.5 %), of which 70 % was phytic, and vitamin D 3 (1 000 IU kg) contents were the same in both diets.

The responses of entire male, castrated male and female growing pigs to dietary lysine concentration was investigated in an experiment involving 144 animals.

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