R. G. Campbell

Effects of sex and energy intake between 48 and 90 kg live weight on protein deposition in growing pigs

Twenty 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 Average daily gain increased quadratically ( P 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 0·75 per day) and 12·4 MJ/day (0·51 MJ/kg M 0·75 per day) for entire males and females, respectively.

Effect of feeding level and dietary protein content on the growth, body composition and rate of protein deposition in pigs growing from 45 to 90 kg

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 P P 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 P 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 P

The influence of feeding level on the protein requirement of pigs between 20 and 45 kg live weight

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.

The effects of sex and live weight on the growing pig's response to dietary protein

Thirty-two entire male and 32 female pigs were used to investigate responses to eight concentrations of dietary protein, with constant amino acid composition ranging from 90 to 248 g/kg over different live-weight stages between 20 and 90 kg. With increasing live weight there was a continuous decline in the concentrations of dietary protein required to support maximum growth and an increasing difference between the sexes in their response to dietary protein. Between 20 and 40 kg live weight sex had no significant effect on growth performance or on the dietary protein concentration for maximum growth ( P > 0·05). Over all heavier live-weight stages entire males grew faster and more efficiently than females, and between 20 and 70, 20 and 80, 20 and 90 and between 50 and 90 kg live weight they responded to higher concentrations of dietary protein than females. During the latter stages of growth, the performance of females was also depressed on the two highest-protein diets. This was associated with a significant increase in carcass fat thickness at 90 kg.

Effects of feeding level from 20 to 45 kg on the performance and carcass composition of pigs grown to 90 kg live weight

Twenty-seven female pigs were used to study the effects of three levels of feeding (low, moderate and ad libitum) from 20 to 45 kg on growth performance and carcass composition to 90 kg live weight. During the live weight phase 20 to 45 kg, raising the level of feeding increased growth rate (P < 0.05), body fat and carcass fat measurements (P < 0.05), but reduced body water (P < 0.05). Subsequent to 45 kg, pigs previously fed at the lowest level grew more rapidly (P < 0.05) and had lower (P < 0.05) feed conversion ratio (FCR) than pigs from either of the other feeding treatments to 45 kg and at 90 kg were leaner (P < 0.05) than pigs offered feeding ad libitum between 20 and 45 kg. For total test (20–90 kg), pigs fed at the lowest level to 45 kg grew at a slower rate (P < 0.05), but had a lower FCR (P < 0.05) than pigs from the other two feeding treatments before 45 kg. Pigs subjected to the moderate feed restriction between 20 and 45 kg grew at a similar rate from 20 to 90 kg, but had a lower FCR (P < 0.05) than those offered feeding ad libitum before 45 kg.

Relationships between energy intake and protein and energy metabolism, growth and body composition of pigs kept at 14 or 32°C from 9 to 20 kg

Thirty-eight pigs weaned at 28 days of age were used to investigate the effects of 4 levels of energy intake (EI, from 6.0 MJ dietary energy (DE) day−1 to ad libitum) and 2 environmental temperatures (14 and 32°C) on protein and energy metabolism, growth performance and body composition between 9.0 and 20.0 kg liveweight. The rates of protein and fat deposition increased linearly with increase in EI at both temperatures. However, the regression coefficients were higher at 14 than at 32°C, such that at low levels of EI, protein and fat deposition were reduced at 14°C compared with 32°C, but the differences diminished as EI increased. When feed was offered ad libitum pigs kept at 14°C consumed 20% more energy, and deposited protein and fat faster, than those kept at 32°C. Growth rate and body-fat content also increased with increase in EI at both temperatures, and were lower at 14°C when EI was restricted. The magnitude of the differences, however, diminished as EI increased; on the ad libitum treatment pigs kept at 14°C grew faster and were fatter than those at 32°C. Feed: gain averaged 1.6 at 32°C, and was unaffected by EI. At 14°C feed: gain was 3.42 at the lowest level of feeding, and improved with each increase in EI to 1.63 when feed was offered ad libitum. The partial efficiency of energy utilization for maintenance and growth was higher at 14 than at 32°C (0.572 vs. 0.458), and the estimated maintenance-energy requirements of pigs kept at 14 and 32°C were 4.56 and 2.18 MJ DE day−1 respectively.

The response of early weaned pigs to sub-optimal protein diets supplemented with synthetic lysine

Thirty male piglets weaned at 20 days of age were fed on either a control diet with 20% crude protein containing 1·1 % lysine or one of two diets with 14·6 or 16·6% crude protein. Synthetic lysine was added to the latter two diets at the rate of 0·00, 0·18, 0·36 and 0·54% to provide four diets with 14·6% crude protein and 0·54, 0·72, 0·90 or 1·08% lysine and four diets with 16·6% crude protein and 0·72, 0·90, 1·08 or 1·26% lysine. All diets were offered ad libitum to piglets between 5·5 and 20·0 kg live weight. Over the live-weight periods 5·5 to 20·0 and 12·0 to 20 kg, live-weight gains and food conversion improved with increasing total lysine to 1·08 % and 0·90 % respectively when pig performance was equal to that achieved on the control diet. The improvement in performance with an increasing level of total lysine during these two periods did not depend on the total protein content of the diet. During the live-weight period 5·5 to 12·0 kg, optimal performance was obtained when pigs were fed on the highest lysine level in the diets with 14·6 and 16·6% crude protein. However, only the diet of 16·6% crude protein promoted pig performance equal to that achieved on the control diet. Carcass quality did not respond to lysine supplementation independently of protein level. With thedietof 14·6% crude protein, optimal carcass quality was obtained with 0·90 % lysine but was significantly poorer than that for the control. With the diet of 16·6% crude protein, carcass quality improved over the entire range of lysine supplementation and with 1·26% lysine was superior to that for the control.