D. Lewis

The interaction between dietary lipids and fibre in the sheep 2. Digestibility studies

Digestibility studies were carried out to establish the inter-relationship between crude fibre and total lipid digestibility in the presence of added calcium or non-ionic detergents. Three levels of calcium, corresponding to daily intakes of 2·3, 4·8 and 22·9 g per sheep, were used in a predominantly ground barley diet (65 to 73%) to which was added 8% beef tallow or maize oil. Two non-ionic detergents were used at 0·1% of the diet: nonyl phenol ethylene oxide and fatty alcohol combined with 3 molecules of ethylene oxide. With a daily intake of 2·3 or 4·8 g calcium per sheep, supplementation with fat resulted in a reduced fibre digestibility. When the intake was increased to 22·9 g, there was a significant improvement (P A possible mechanism by which the physical wetting of dietary lipids causes decreased digestibility of the fibre component is discussed.

Amino acid requirements of growing pigs. 7. The response of pigs from 25 to 55 kg live weight to dietary ideal protein

One hundred and twenty pigs were used in a 3 × 8 factorial design. The factors were sex, 40 trios of littermate boars, castrated males and gilts, and dietary lysine, eight concentrations from 7×5 to 14×5 g/kg diet with 1 g/kg diet intervals of lysine with corresponding crude protein (CP) concentrations from 114 to 226 g/kg diet. Increases in dietary lysine were associated with concomitant increases in the other essential amino acids so as to provide an ideal protein. All diets had similar digestible energy values (13·65 MJ/kg). Pigs were fed once daily on a restricted scale from 25 to 55 kg live weight. For growth and carcass characteristics there was a range of linear response followed by a plateau. The inflexion points of dietary lysine for growth characteristics were at 11·1, 10·2 and 10·9 g/kg diet (171, 157 and 168 g CP per kg diet) together with daily intakes of 18·0, 16·7 and 17·6 g (daily intake of 277, 257 and 271 g CP) for boars, castrated males and gilts respectively. The equivalent points for carcass characteristics were 10·4, 9·7 and 10·1 g/kg (160, 149 and 156 g CP per kg diet) with daily intakes of 16·9, 15·9 and 16·4 g lysine (daily intakes of 260, 245 and 252 g CP). Blood urea data gave good support for these observations.

Influence of energy and protein concentration in the diet on the performance of growing pigs 1. Response to protein intake on a high-energy diet

Sixty gilts by Landrace sires out of Large White × Landrace females were allocated on the basis of litter relationship and initial weight to six treatments involving the individual feeding of six dietary protein levels, 15·5%, 17·4%, 20·2%, 22·3%, 25·3% and 27·3% crude protein (CP), at a common energy level of approximately 3500 kcal/kg DE, from 23 to 59 kg live weight. Amino acid balance was maintained relatively constant with synthetic lysine, methionine and tryptophan. There were significant increases in growth rate and efficiency of feed conversion from the 15·5% to the 17·4% CP diets and significant reductions in both from the 25·3 % to the 27·3 % CP diets. Carcass lean by dissection increased linearly ( r = 0·976) and fat decreased linearly ( r = −0·992) with dietary protein increment over the full range studied. As best growth performance and maximum lean content were attained at different dietary CP levels, a combined measure of daily lean deposition was calculated; this indicated that maximum rate of lean growth and efficiency of feed conversion to lean were reached on the 22·3% CP level. In terms of efficiency of utilization of nutrients, maximum retentions of both DE and DCP in the edible part of the carcass appeared to be attained on the two lowest dietary protein levels.

Influence of energy and protein concentration in the diet on the performance of growing pigs 3. Response to differences in levels of both energy and protein

One hundred and twenty eight gilts by Landrace sires out of Large White × Landrace females were allocated on the basis of litter relation-ship and initial weight to 16 treatments involving the individual feeding of four dietary protein levels (approximately 15%, 18%, 21% and 24% CP) at each of four energy levels (2830, 3100, 3375 and 3585 kcal DE/kg air-dry feed). Amino acid balance (as% of total CP) was maintained relatively constant, using synthetic lysine and methionine where necessary. Growth performance was measured over a live-weight range of 23 kg to 59 kg, at which latter weight the pigs were slaughtered for carcass evaluation by dissection of the middle ‘joint’ from a half carcass. Linear carcass measure-ments were also taken. There was a significant energy × protein interaction only for killing-out percentage; for all other measures the main effects could be assessed independently. Increase in dietary energy value gave linear increase in growth rate (GR) and improve-ment in efficiency of feed conversion (EFC), accompanied by linear decrease in lean percentage and increase in fat percentage. Increase in dietary protein level gave an increase in GR and improvement in EFC with the first increment (from 15% to 18% CP), but depressions in both these characteristics with the final increment (from 21% to 24% CP). Lean percentage increased and fat percentage decreased with the first protein increment, with no further significant changes. Calculation of daily rates of tissue deposition indicated that maximum rate and efficiency of fat-free carcass gain could be attained with the second lowest energy and protein levels tested (i.e. 3106 kcal DE/kg and 18·2% CP).

Amino acid requirements of growing pigs 5. The interaction between isoleucine and leucine

Thirty-two female growing pigs (25 to 55 kg live weight) were subjected to four dietary treatments combining two levels of isoleucine and two levels of leucine to investigate the effects of leucine supply on the requirement for isoleucine. Results for daily live-weight gain, food conversion efficiency and carcass quality judged by ham dissection indicated that 3·8 g isoleucine per kg diet was marginally adequate for the growing pig in diets containing 13·4 g leucine per kg. An interaction between dietary leucine and isoleucine was demonstrated. Increasing the dietary leucine concentration to 20·4 g/kg clearly resulted in a deficiency of isoleucine in the basal diet, as daily gain, food conversion efficiency and carcass quality were significantly improved by increasing the isoleucine concentration from 3·8 g to 4·5 g/kg diet. Dietary leucine concentration did not influence performance at the higher level of isoleucine supply. Changes in plasma urea and amino acid concentrations confirmed the findings from the growth experiment of the interaction between isoleucine, leucine and valine.

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

Sixty-four growing pigs, with equal numbers of females and castrated males, were fed diets containing from 10 to 17·6% crude protein but in which lysine was maintained at 0·95%. Over the 25 kg to 55 kg live-weight range studied, growth performance was unaffected by a reduction in crude protein level from 17·6 to 14·5%. Below 14·5% crude protein, daily live-weight gain and feed conversion ratio deteriorated linearly. Percentages of lean meat and fat in the middle joint showed similar trends. Significant sex effects were confined to carcass characteristics which indicated that the females produced leaner carcasses. It was concluded that below 14·5% crude protein a deficiency of the next limiting amino acid to lysine, or possibly non-essential nitrogen, depressed growth performance.

Amino acid requirements of growing pigs. 6. Isoleucine

The response of the growing female pig (25 to 55 kg live weight) to increasing dietary isoleucine supplies at two levels of dietary leucine was assessed by measurement of growth rate, food utilization, tissue deposition as indicated by ham dissection and changes in plasma urea concentration. A range of isoleucine concentrations from 3·7 g/kg to 5T g/kg of the diet was derived from a basal diet and seven increments of L-isoleucine. Synthetic L-leucine was added to the basal diet to increase the concentration from 12 g/kg to 15 g/kg to achieve the two levels. The basal diet was formulated using barley, maize, blood meal, yeast protein, fat and tapioca with synthetic amino acids included to maintain at least 9·5 g/kg lysine and adequate concentrations of other essential amino acids and non-essential nitrogen. The 16 diets were replicated four times and fed to 64 female growing pigs once daily according to a restricted feeding scale. Blood samples were taken from each pig at 40 kg live weight for the determination of plasma urea nitrogen. The addition of synthetic leucine to the basal diet had no consistent effect on growth performance or carcass quality, although it did result in elevated levels of plasma urea nitrogen. The response of growth performance and the composition of the ham joint to increasing dietary isoleucine concentration was interpreted by broken line functions which indicated an isoleucine requirement of 4·4 to 4·5 g/kg of the diet.

Amino acid requirements of growing pigs 2. Identification of the limiting amino acid(s) in a low-protein diet supplemented with lysine

A basal diet containing 120 g crude protein per kg and 9g lysine per kg, and previously shown to be limiting in one or more essential amino acids and/or non-essential nitrogen, was examined. It was fed either alone to growing female pigs from 25 kg to 55 kg live weight or in combination with four supplements of synthetic amino acids each containing three out of isoleucine, methionine, threonine and tryptophan. A control diet containing 140 g crude protein per kg and 9g lysine per kg was also included. Blood samples were collected at 40 kg live weight in order to examine the influence of dietary treatments on blood metabolites. Results for growth performance, carcass composition and blood urea indicated that threonine was the first limiting amino acid in the basal diet. Plasma free amino acids gave no clear trend. Growth performance and carcass composition were unaffected by supplementation of the diet with glycine indicating that the dietary supply of non-essential nitrogen was adequate.

Influence of energy and protein concentration in the diet on the performance of growing pigs 4. Effects of sex on response to dietary protein level

Two barrows and two gilts from each of 16 litters, by Landrace sires out of Large White × Landrace females, were fed individually one of 4 dietary protein levels (approximately 14%, 17%, 20% and 23% CP) at a common energy level (approximately 3165 kcal/kg DE), from an initial weight of 23 kg to slaughter at 59 kg. The 17% CP diet gave 19% faster growth and 17% better feed conversion than the 14% CP diet (P There were no significant differences between sexes in growth rate, efficiency of feed conversion or carcass composition. Only depth of backfat on the shoulder and at ‘K’ and carcass length showed significant (P

Tenderness and the calpain system of three different types of muscles of Kejobong does under two different energy levels.

Abstract. The purpose of research was to investigate whether there was influence of the addition of concentrates in basal feed on meat tenderness and calpastatin and calpain activities of three muscles of Kejobong does. A total of 20 heads of Kejobong does (2.0-2.5 years) with initial live weight range between 23.8-24.2 kg was studied and randomly set in two kinds of feed treatment, ie basal feed (p 0 ) and basal feed plus concentrates (p 1 ). Two kinds of feed were given to Kejobong doe for 12 weeks.xa0xa0 The observed variables were (1) tenderness of meat, (2) calpain activity (m-calpain activity and the activity of m-calpain), and (3) calpastatin activity. Data were processed using the General Linear Model Univariate procedure and Pearson Bivariate Correlation of the SPSS program.xa0 Results showed that feeding (basal feed and basal feed plus concentrates) significantly affected meat tenderness of Kejobong doe. The types of muscles had highly significant effect on tenderness. Feeds affected m-calpain activity, m-calpain activity, and calpastatin activity in the muscles. Types of muscles exhibited variation in the activity of m-calpain, the activity of m-calpain, and calpastatin activity. xa0In conclusion, the addition of concentrates in the basal feed increased meat tenderness, and affected the activity of m-calpain, m-calpain, and calpastatin. Key w ords :xa0 activity of m-calpain and m-calpain, calpastatin activity, Kejobong doe Animal Production 14(1):47-55, January 2012