Protein, lysine and feed intake level effects on pig growth: I. Main effects

Abstract

SUMMARYA total of 512 pigs were given from 50 lb live weight one of 16 diets, i.e. with 4 lysine levels at each of 12, 14, 16 and 18% protein, at one of 4 levels of intake. They were killed at 100, 150, 200 or 250 lb live weight.Live-weight gain was not improved significantly by increasing the protein level above 16, 14, 12and 12%, respectively, for the 50–100, 100–150, 150–200and200–2501bstages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the protein to 18%. Gain in lean meat and in the efficiency of conversion of feed to lean meat were improved by increasing the above protein levels slightly.Live-weight gain was not improved significantly by increasing the lysine level above 1·04, 0·74, 0·70 and 0·59%, respectively, for the 50–100, 100–150, 150–200 and 200–250 lb stages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the lysine level to 1·22%. Raising the lysine level at each level of protein had no significant effect on the rate and efficiency of lean meat gain.Live-weight gain was significantly improved by increasing the level of feed intake almost to ad libitum levels for the 50–100, 100–150 and 150–200 lb stages. There was a suggestion of a similar effect in the 200–250 lb pigs although it was not statistically significant. Conversion of feed to live-weight gain was improved in the 50–100 lb pigs only by increasing the level of feed intake: in the older pigs increasing the level of feed intake caused a worsening in feed conversion ratio. Increasing the level of feed intake gave a significant improvement in rate of lean meat gain but a significant worsening in the efficiency of conversion of feed to lean meat during all stages up to 200 lb.Interaction effects of these factors and sex, on growth performance, are described.

Protein levels in diets for European pigs in the tropics. 2. The effect of lysine and methionine supplementation on the protein requirement of growing pigs

“…In an earlier experiment (Fetuga et al, 1975) optimal performance had been obtained in the presence of adequate methionine plus cystine, at a total dietary lysine level between 0-96 and 1 -07 % which is close to the values reported by Cooke et al (1972) and Blair et al (1969a and b). It is possible, therefore, that the higher values observed in the present study, may have been a result of differences in the availability of amino acids in the various protein concentrates used, thus pointing to some of the problems that might be encountered in meeting the animals' requirements from different batches of the same feedstuffs, which may differ in the level of the available amino acids.…”

Amino acid requirements of growing pigs. 1. Effects of reducing protein level in diets containing high levels of lysine

“…327 (Blair, Dent, English and Raeburn, 1969a and b;Henry, Rerat and Tomassone, 1971) and previous experiments at the University of Nottingham (Crehan, Lewis and Lodge, 1966), appeared to be the optimum dietary concentration for pigs of the live weight studied. the dietary level at which optimum performance is achieved.…”

“…Similarly, Blair et al (1969a and b) found that the carcasses of females contained a higher proportion of lean meat than castrates at 68 kg live weight. Similarly, Blair et al (1969a and b) found that the carcasses of females contained a higher proportion of lean meat than castrates at 68 kg live weight.…”

The energy and nitrogen metabolism and performance of pigs infected with Oesophagostomum dentatum

“…Animals may also change to some extent their protein requi rement in cases of low and high protein supplies (Mollgaard , 1931 ;Paquay , 1968) , due to a change in excretion of urea with the urine (Allison ,56 19 59 The changes in performance that accompany changes in the plane of nutrition us ing a fixed diet can equally well be regarde d as consequences of raised protein allowance as of energy intake , the two situations differing in that wh en protein percentage is increased th ere are only small changes in energy supply , when da ily feed allowance is raised there is a proportional increase in daily energy (Chamberlain, 1972) . Blair et al (1969aBlair et al ( , 1969b and Davies (1970) both agree th at the rate of gain of lean meat responds to daily feed intake in pigs 25 kg liveweight fed � 1 kg meal/day up to pigs 100 kg liveweight fed �3 kg wh ich can be interpreted as a respons e to increased daily energy or protein allowance or both . The efficiency of utilization of protein for lean meat production de clined as intake increased (Chamberlain , 1972) .…”

“…Even where intake is contro lled (Woodman et al, 19 36;Lucas and Calder, 1956 ;Blair et al , 1969a ;1969b) gilts have been leaner than barrows .…”