D. J. A. Cole

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.

Prediction of the apparent digestible energy value of fats given to pigs

Data from experimental programmes designed to investigate the effect of chemical structure of fats upon their apparent digestible energy (DE) value for pigs were subjected to regression analysis. For growing pigs, over the approximate live-weight range 30 to 90 kg, 25 data points were available, with fats evaluated having a range in the ratio of unsaturated to saturated fatty acids (U/S) from 0·66 to 15·67 and in free fatty acid (FFA) content from 8 to 818 g/kg. Sixteen data points were available for young pigs of approximately 12 kg live weight with a range in U/S from 0·62 to 5·71 and in FFA content from 54 to 756 g/kg. The wide range of values for U/S and FFA content had been obtained by blending different fats and, therefore, represented both the range and extremes likely to be found in the formulation of pig diets. Derivation of prediction equations for DE were based upon a series of non-linear regression analyses employing, in sequence, U/S, U/S + FFA content and U/S × FFA content. The DE offats could be predicted from U/S and FFA content with equations accounting for 0·802 and 0·768 of the variation in DE values for growing and young pigs respectively. The most appropriate equation for pigs of all live weights employed U/S and FFA content additively (U/S + FFA content). The equation for growing pigs was DE (MJ/kg) = 36·898 – (0·0046FFA (g/kg)) — 7·33e(–0·906U/S) and for young pigs was DE (MJ/kg) = 37·890 — (0·0051FFA (g/kg)) –8·20e(–0·515U/S). Comparisons revealed that differences between the two age groups, with lower values achieved with younger pigs, -were more pronounced the lower U/S and the higher FFA content of the fat.

The dietary energy values of soya-bean oil, tallow and their blends for growing/finishing pigs.

Two fats, soya-bean oil and tallow, were blended in the ratios 70: 30, 50: 50 and 30: 70. The ratios of unsaturated to saturated fatty acids (U/S) of the blends were 3·18, 2·08 and 1·49 respectively; values for soya-bean oil and tallow were 6·69 and 0·93. These five fat sources were each included into a basal diet at levels of 40, 80 and 120 g/kg. The digestible (DE) and metabolizable (ME) energy together with the apparent fat digestibility (AFD) of the experimental diets were measured in a metabolism trial based upon four 4 × 4 Latin squares using 16 gilts of 30 kg initial live weight. Linear equations relating dietary DE and ME values to level of inclusion of fat were extrapolated to 1000 g/kg to obtain values for the fats. DE values for soya-bean oil and tallow were 38·06 and 34·16 MJ/kg respectively. Corresponding data for ME were 35·63 and 32·53 respectively. These figures were used to calculate values of the mixtures. Data thus derived did not differ significantly from those determined directly, indicating that there was no synergism between the two fats. DE values of fats determined as the product of AFD of fats and their gross energy followed similar trends. The majority of the increase in values of fats was associated with a change in the U/S ratio from 0·93 to 2·08.

The effect of lysine/digestible energy ratio on growth performance and nitrogen deposition of hybrid boars, gilts and castrated male pigs

An experiment was conducted to examine the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) on growth performance and body composition of boars, gilts and castrated males from 25 to 90 kg live weight. Twelve pigs (four of each sex) were assigned to each dietary treatment consisting of lysine/DE ratios from 0·4 to 1·4, in 0·2 g/MJ increments. Food was provided at proportionately 0·90 ad libitum and at 90 kg all pigs were slaughtered and the body composition of two pigs per sex per treatment was determined. Responses to lysine/DE ratios were similar for all sexes up to the optimum level after which daily live-weight gain (DLWG) and nitrogen deposition rate (NDR) deteriorated in gilts and castrated males. This deterioration may have been due to energy used for deamination of excess protein not being availablefor growth processes. Lipid deposition rate (LDR) remained constant from the 0·4 to 0·8 g/MJ lysine/DE ratios and then decreased sharply to a lower plateau from the 1·0 to 1·4 g/MJ lysine/DE ratios suggesting that DE levels were adequate to meet NDR requirements up to the 1·0 g/MJ lysine/DE ratio when it became limiting. The optimum lysine/DE ratio for the genotype tested from 25 to 90 kg live weight was of the order of 0·95 to 1·0 g/MJ. The maximum NDR of the genotype tested appears to be of the order of 28 to 30 g/day (175 to 187 g/day protein deposition rate).

Effect of chemical structure of fats upon their apparent digestible energy value when given to young pigs

The effect of degree of saturation (ratio of unsaturated to saturated fatty acids, U/S) and free fatty acid (FFA) content of fats upon their digestible energy (DE) values was investigated in post-weaning pigs. The two fats evaluated were soya-bean oil (SO) and tallow (T) (representing extremes of saturation) together with their acid oils (SAO and TAO respectively) providing high FFA levels). Blends of the four fats provided treatments with varying FFA content and U/S ratios. The experimental fats were evaluated by substitution, at 40, 80 and 120 g/kg into a basal diet, in a randomized-block design, with 98 gilts and 98 boars of approximately 12 kg live weight. Pigs had been weaned at 28 days of age and experimental diets were given 7 days after weaning. When pigs obtained a weight of 10 kg the inert marker titanium dioxide was added to the diets as a reference substance. A 5-day adjustment period was allowed followed by a 5-day collection period of faeces by grab sampling. Fat content of food and faeces, with methodology based on acid hydrolysis, allowed calculation of apparent digestible fat (AFD) of experimental diets. Analysis of variance demonstrated effects of fats, rates of inclusion, and fats × rates ( P

Meat production from pigs which have farrowed 1. Reproductive performance and food conversion efficiency

The reproductive performance and food conversion efficiency ofyoung female pigs (gilts) destined for slaughter after weaning their first litter were investigated using four treatment groups of 19 Landrace × (Landrace × Large White) gilts. In two treatment groups gilts were mated at pubertal heat and suckled for 5 to 11 and 35 to 42 days respectively. These gilts were slaughtered following weaning. A third group of gilts were conventionally mated at third oestrus and suckled for 35 to 42 days. These animals acted as controls for reproductive performace. The fourth treatment group consisted of unmated gilts, slaughtered at 118 kg live weight, which served as controls for food conversion efficiency, growth rate and carcass measurements. There were no significant differences in either the number or weight of piglets born in any of the treatment groups. The food conversion efficiency and growth rate of the mated gilts was significantly (P

Studies in sow reproduction 4. The effect of level of feeding in lactation and during the interval from weaning to remating on the subsequent reproductive performance of the early-weaned sow

An investigation of the effects of level of nutrition, both in lactation and from weaning to remating, on subsequent litter size and associated reproductive characteristics in the early-weaned sow is reported. Subjects were 75 sows in 5 groups. In 4 of the groups the sows were weaned after a 10-day lactation period. Group 5 was weaned following a 42-day gestation. The control group was fed up to 6.3 kg/day during lactation and 2.7 kg/day from weaning to remating. The 4 early-weaned groups were each fed differently. In lactation and during the inverval from weaning to remating they were fed either 2 or 4 kg/day. The group receiving only 2 kg/day during each period lost more weight than the others (p less than .05). Weight loss in lactation was significantly (p less than .001) affected by feeding. Sows weaned after a 10-day lactation period farrowed 2.7 piglets/litter less in the next parity than sows weaned after a 6-week lactation period. Weight losses during lactation were not related to subsequent litter size. Level of nutrition from weaning to remating in these tests had no influence on subsequent litter size. The early-weaned sow, even with large fluctuations in weight change over the period from parturition to remating, did not alter their ceiling for litter size. It seems unlikely that ovulation rate is the major factor limiting litter size in the early-weaned sow. Results suggest that embryo mortality following ovulation and coitus is increased in the early-weaned sow and that this effect then manifests itself as a ceiling to subsequent litter size.

Reproduction in the gilt 3. The effect of exogenous oestrogen on the attainment of puberty and subsequent reproductive performance

Ten Landrace × (Landrace × Large White) young female pigs were allocated to each of four treatments. The experiment was arranged as a 2 × 2 factorial design, the variables being oestradiol benzoate v. ethyl oleate and boar v. visual testing. The oestradiol benzoate (or ethyl oleate) was administered at 140 days of age, the treatment consisting of six injections, over a 3-day period, of 0·5 ml of either ethyl oleate or a solution of 0·4 mg/ml β-oestradiol-3-benzoate in ethyl oleate. Subsequently the gilts were either inspected visually each day or taken to a vasectomized boar for oestrus detection. All gilts were mated at the second oestrous period, and slaughtered on the 20th day of gestation. Those gilts receiving exogenous oestrogen attained puberty significantly earlier (P

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.

Growth and body composition of highly selected boars and gilts

An experiment was conducted to measure the growth and body composition changes of highly selected boars and gilts from 10 to 150 kg live weight. Thirty boars and 30 gilts were given food ad libitum and two pigs of each sex were slaughtered at 10-kg increments from 10 kg to 150 kg live weight at which time the chemical composition of the body was determined. Boars and gilts exhibited different patterns of growth, nitrogen deposition rate (NDR) and lipid deposition rate (LDR) with boars exhibiting a sharp peak in daily live-weight gain and NDR while gilts exhibited almost a flat response curve over the age and weight range tested. Gilts experienced a peak in LDR at a lighter weight than boars (75·8 v. 100·5 kg) while NDR peaked at the same weight for both sexes (70·8 kg). Maximum NDR for boars and gilts was 37·7 and 28·1 glday (235·5 and 175·5 glday protein deposition rate) respectively. The Gompertz growth equation [Y = A + C × EXP (−EXP (−B ×(X−M)))] was shown to accurately represent the growth trajectory, while the logarithmic derivative of the allometric equation [Y = aX b ] was used to determine live weight and body composition relationships. Combined sex relationships indicated that total body nitrogen and lipid concentrations increased at the same rate. A quadratic equation for the prediction of NDR based on live weight was developed for this genotype (NDR = 24·06 + 0·34 W − 0·002W 2 ). In conclusion, the results provide a basis for comparison of body composition and growth patterns between the highly selected genotype tested and pigs from other genetic backgrounds. Sex effects exist for growth and body composition but combined sex prediction equations can be used to estimate NDR potential.