Seventy-two crossbred (Large White X Landrace) pigs were used in a 3 X 7 factorial experiment to investigate the response of two strains of boars (strains A and B) and of castrated male pigs (strain B) to seven levels of intake of a single diet (ranging from 5.3 Mcal digestible energy [DE]/d to ad libitum) between 45 and 90 kg live weight. All aspects of growth performance and body composition were affected to different degrees by both strain and sex. At all levels of energy intake strain A boars grew faster, had a lower feed to gain ratio and contained less fat and more water in the empty body than strain B boars, which in turn exhibited faster live weight gain and more efficient and leaner growth than castrated males. The magnitude of the differences in growth performance between strain A and strain B boars and castrates increased with increased energy intake above 7.88 Mcal DE/d, and these differences were associated with concomitant strain differences in their respective capacity for protein growth and in the relationship between energy intake and protein deposition. For strain A boars the rate of protein deposition increased linearly from 92 to 188 g/d with increased energy intake from 5.3 Mcal DE/d to ad libitum. For strain B boars and castrates the rate of protein deposition increased linearly with increased energy intake up to 7.88 Mcal DE/d, but thereafter it remained constant at 128 and 85 g/d, respectively. For castrates protein deposition was depressed (P less than .01) when the diet was offered ad libitum. Strain A boars had a higher energy requirement for maintenance (3.55 Mcal DE/d) than strain B boars (2.77 Mcal DE/d) or castrates (2.60 Mcal DE/d). Strain A boars also contained less protein and more water in the fat free empty body than the other two pig types.

The availability of lysine and the ileal digestibility of amino acids in three cottonseed meals and a soyabean meal for growerlfinisher pigs were determined. The usefulness of the availability estimates for formulating diets was assessed. The availability of lysine, as assessed with a slope-ratio assay, was (proportion of total): cottonseed meal no. 1, 0.27; no. 2, 0.30; no. 3, 0.29; soya-bean meal, 0.90. Ileal digestibility of lysine in the meals (proportion of total) was: cottonseed meal no. 1,0.58; no. 2,068; no. 3,0.72; soya-bean meal, 089. Pigs given diets formulated to the same available lysine concentration grew at similar rates and retained the same amount of lysine in the carcasses. The results indicate that, for meals of high availability (soya-bean meal), reduced ileal digestibility appears to be the main reason for reduced availability. However, in meals of low availability (cottonseed meal), reduced ileal digestibility only accounts for part of the reduced availability. Thus, the ileal digestibility of lysine is not a reliable indicator of lysine availability.Lysine: Ileal digestibility : Availability : Cottonseed meal: Soya-bean meal: Pigs Previous work (Batterham et al. 1979, 1984) indicated that the availability of lysine in cottonseed meal, as assessed by slope-ratio assays, was low for pigs (0.394.43). This was in contrast to soya-bean meal, where lysine availability was high (0.84-0.98). The low lysine availability in cottonseed meal is presumably due to the processing conditions used in the extraction of oil and inactivation of the toxin, gossypol. It is necessary to formulate diets on an available lysine basis to take into account the large difference in availability for growing pigs that occurs between the different protein concentrates.Slope-ratio assays are time-consuming and expensive to conduct and interest has centred on the use of the ileal digestibility assay to estimate amino acid availability. This assay also has the advantage over slope-ratio assays in that the digestibility of all amino acids can be assessed at the same time and only small numbers of pigs are required per assay. The assumption is made that, if an amino acid is not recovered at the terminal ileum, then it has been absorbed in a form suitable for utilization. This assumption is not strictly correct, as amino acids can be absorbed in forms that are not efficiently utilized (e.g. 6-N-propionyl-L-lysine in rats (Bjarnason & Carpenter, 1969)). Thus, ileal digestibility can overestimate availability.Despite the interest in these assays, there have been few studies of the relationship between ileal digestibility and lysine availability. In comparative studies with one sample of lupin (Lupinus aZbus)-seed meal, the ileal digestibility of lysine for finisher pigs (0.86;

1. Eight diets of similar energy content, ranging in crude protein concentration from 95 to 256 g/kg, were given at either 2-5 or 3-2 times the energy level for maintenance to entire male pigs growing from 45 to 90 kg live weight.2. Growth rate improved with increase in feeding level and with increasing dietary crude protein up to 164 g/kg (P < 0-05). The food conversion ratio improved with each increase in dietary CP up to 186 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 0-05). It was also improved with increase in level of feeding of the lower-protein diets but deteriorated with increase in level of intake of the higher-protein diets (P < 005).3. Rate of protein deposition improved with increasing dietary crude protein up to 186 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 005). The results showed that, for pigs given diets deficient in crude protein, rate of protein deposition was linearly related to protein intake (P < 0-001) but independent of energy intake. For pigs given a diet adequate in crude protein, rate of protein deposition was related to energy intake and independent of crude protein intake.4. Body fat content at 90 kg decreased with increasing dietary crude protein up to 210 and 164 g/kg on the lower and higher feeding treatments, respectively (P < 0-05), and was increased by raising the level of intake of the higher-crude protein diets (P < 0-05). However, the influence of feeding level on body fat diminished as dietary crude protein was reduced.

Link to this article: http://journals.cambridge.org/abstract_S0003356100040198How to cite this article: R. G. Campbell, M. R. Taverner and D. M. Curic (1985). Effects of sex and energy intake between 48 and 90 kg live weight on protein deposition in growing pigs. ABSTRACTTwenty four entire male and 24 female pigs growing from 48 to 90 kg live weight were used to investigate the effects of five rates of food intake supplying daily between 23 MJ digestible energy (DE) and 41-8 or 39-2 MJ DE for entire males and females respectively, on rate of protein deposition, and on growth and body composition.Entire males deposited protein faster than females, and for both sexes the rate of protein deposition increased linearly with increase in energy intake up to 33 MJ DE per day (P < 0-001) but was not significantly affected by further increase in energy intake.Average daily gain increased quadratically (P < 0-001) with increase in energy intake and at all levels was higher for entire males than for females. Food:gain ratio (g food per g growth) which was lower for entire males improved with increase in energy intake up to 33 MJ DE per day and deteriorated with further increase in energy intake.At 90 kg live weight entire males contained less fat and more protein and water in the empty body than females. For both sexes, body fat content increased at a decreasing rate with increase in energy intake up to 33 MJ DE per day, and at an increasing rate with further increase in energy intake.Total energy retained was linearly (P < 0-001) related to energy intake and at all rates of energy intake was higher for females than for entire males. The estimates of DE required for maintenance were 15-9 MJ/day (0-664 MJ/kg M 075 per day) and 12-4 MJ/day (0-51 MJ/kg M" 75 per day) for entire males and females, respectively.

One hundred entire male pigs growing between 20 and 45 kg live weight were used to investigate the effects on growth performance and carcass composition of eight concentrations of dietary crude protein (CP), ranging from 93 to 238 g/kg and three levels of food intake (giving mean daily digestible energy 15·6, 18·7 and 22·4 MJ).Growth rate improved with each increase in food intake and with increase in dietary CP up to 175 g/kg (10·5 g lysine per kg) at all food intakes. Food:gain ratio (g food per g growth) improved with increase in dietary CP up to 175 g/kg and with the first increase in food intake.The rate of protein deposition in the carcass (excluding viscera) increased with each increase in level of feeding, and with increases in dietary CP up to 175 g/kg. The results showed that for pigs given diets deficient in protein, the rate of protein deposition was linearly related to protein intake and independent of energy intake. For pigs given diets adequate in protein, the rate of protein deposition was related to energy intake, and independent of protein intake.The carcass fat of pigs killed at 45 kg live weight decreased on all feeding treatments with increase in dietary CP up to 175 g/kg, and was higher in pigs given the two higher levels of feeding than in those fed at the lowest level. The effect of feeding level on carcass fat content declined as the protein adequacy of the diet was reduced.