Efficiency of food conversion and body composition of the preruminant lamb and the young pig

Dietary supplementation with monosodium glutamate enhances milk production by lactating sows and the growth of suckling piglets

This study was conducted to test the hypothesis that increasing dietary content of glutamate through addition of monosodium glutamate (MSG) enhances milk production by lactating sows and the growth of their offspring. Thirty multiparous sows (Landrace × Large White) were assigned randomly into one of three dietary groups: control (a corn- and soybean meal-based diet), the basal diet + 1% MSG, and the basal diet + 2% MSG. Diets were made isonitrogenous by the addition of appropriate amounts of L-alanine. Lactating sows had free access to drinking water and were fed twice daily their respective diets. The number of live-born piglets was standardized to 9 per sow at day 0 of lactation (the day of farrowing). On days 3, 15, and 29 of lactation, body weight and milk consumption of piglets were measured, and blood samples obtained from sows and piglets at 2 h and 1 h after feeding, respectively. Feed intake of sows did not differ (P > 0.05) among the three groups of sows. Concentrations of aspartate, glutamine, citrulline, arginine, tryptophan, proline, branched-chain amino acids, and glutamate were greater (P < 0.05) in the plasma of MSG-supplemented sows and their piglets than for controls. When compared with the control, dietary supplementation with 1-2% MSG increased (P < 0.05): concentrations of many free amino acids (including glutamate plus glutamine) and all protein-bound amino acids in milk; the milk intake of piglets by 14-25%; and daily weight gains of piglets by 23-44%. These results indicate that dietary supplementation with 1-2% MSG to lactating sows enhances milk production to support the growth of sow-reared piglets.

Metoclopramide induces preparturient, low-level hyperprolactinemia to increase milk production in primiparous sows

Inadequate milk production by sows often limits the growth of piglets. A successful lactation requires prolactin (PRL)-induced differentiation of the alveolar epithelium within the mammary glands of sows between days 90-110 of gestation. We hypothesized that induction of late gestational hyperprolactinemia in primiparous sows by oral administration of the dopamine antagonist metoclopramide (MET) would enhance mammary epithelial differentiation, milk yield, and piglet growth rate and that these effects would carry over into a subsequent lactation. Twenty-six gilts were assigned to receive either MET (n = 13, 0.8 mg/kg) or vehicle (CON, n = 13) twice daily from days 90-110 of gestation. The same sows were followed into their second lactation without additional treatment. On day 90 of gestation, circulating PRL concentrations peaked 45 min after feeding MET (P < 0.001) and then returned to baseline 3 h later. This response occurred daily out to day 104 of gestation (P < 0.05). Compared with CON, MET-treated gilts had enlarged alveoli on gestation day 110 (P < 0.05). Treatment with MET did not affect feed intake, body weight, or body fatness during pregnancy or lactation. Piglets born to MET-treated sows had both increased body weights and average daily gain on lactation days 14 and 21 (P < 0.05). Milk intake by piglets was estimated from deuterium oxide dilution. Although milk intake by piglets nursing MET sows was not statistically different from those nursing CON sows on day 21 of lactation (P = 0.18), there was a greater increase in milk consumption by piglets born to MET-treated sows between days 9 and 21 of lactation than for those in CON litters (P < 0.001). In one group of second parity sows (n = 11) that were treated with MET during their first gestation, milk yield increased by 21% during their second lactation (P < 0.05) in association with a 14% decline in body fatness across lactation compared with a 7% decline in CON sows (P < 0.05). These findings demonstrate that MET-induced hyperprolactinemia in primiparous sows during late pregnancy can increase milk yield and piglet growth rate, setting the stage for further large-scale studies.

Extended nursing and/or increased starter diet allowances for low weaning weight pigs

Objective

To evaluate the use of nurse sows and post-weaning nutrition strategies for low wean weight (WW) pigs on lifetime growth and efficiency.

Methods

Animals (n = 270) were assigned to one of five treatments at 28 d. Low WW pigs (<6 kg) were either weaned and offered a special dietary regime recommended for low WW pigs (WEAN) or placed on a nurse sow (NURSE) and weaned at 49 d. Normal WW pigs (9 kg) (NORM) were also weaned at 28 d. After weaning, NORM and NURSE pigs were offered either a ‘high’ (4 kg/pig of starter 1 diet followed by 8 kg/pig of starter 2 diet) or ‘low’ (8 kg/pig of starter 2 diet) starter diet allowance in a 2×2 factorial arrangement. A typical grower diet was then offered, followed by a typical finisher diet until 147 d of age.

Results

NORM pigs where heavier throughout their life compared to NURSE pigs (91.4 kg vs 76.2 kg at 147 d; p<0.001). WEAN pigs were heavier at 70 d compared to NURSE pigs (23.9 kg vs 21.0 kg; p<0.001), but there was no significant difference at 147 d between NURSE and WEAN treatments. NURSE pigs had reduced feed intake throughout the finishing period (1.6 kg/d; p<0.001) compared to WEAN (2.0 kg/d) and NORM (1.9 kg/d) pigs. Feed conversion ratio (FCR) of NURSE (2.20) was lower than NORM and WEAN during the finishing period (2.40 and 2.79, respectively).

Conclusion

Extended (up to 49 d) nursing for low WW pigs resulted in improved FCR during the finishing period, but no overall improvement in growth rate compared to low WW pigs weaned at 28 d and offered a specialised starter regime. Normal WW pigs where significantly heavier than low WW pigs throughout the study.

Genetic components of potential and actual growth

1. It is shown how the growth of an animal in non-limiting conditions can be predicted from the values of a small set of animal variables. The functions used are derived from a small set of simple, and reasonable, assumptions.

2. Growth may be limited by intakes of nutrients and energy which are less than those needed. The prediction of growth where such limitation occurs calls for the prediction of the intakes. There may be genetic variation in the abilities of animals to deal with the relevant constraints which are, commonly, feed bulk or hot environments.

3. Breeders need to pay more attention to giving sufficient descriptions of their stocks.

Body chemical composition and efficiency of energy and nutrient utilization by growing pre-ruminant Saanen goat kids

An experiment involving a feeding trial and a comparative slaughter was conducted to assess the body chemical composition and patterns of nutrient utilization in pre-ruminant Saanen goat kids. Thirty male kids weighing about 6 kg were divided into five equal groups, one of which was slaughtered as the reference group (G0). The remainder were randomly assigned to four feeding levels of 250, 290, 330 and 370 g goats’ milk per kg M0·75 per day and named as groups GI, GII, GIII and GIV, respectively up to about 15 kg live weight, after which they were slaughtered. Mean milk consumption per unit live-weight gain (LWG) (kg/kg), and daily LWG (g/day), for GI, GII, GIII, GIV respectively were: 13·5 and 110; 10·5 and 160; 10·2 and 180; and 10·3 and 200. Empty body weight (EBW) as a proportion of final live weight was 0·95 in the reference animals, and ranged from 0·80 to 0·88 in the treatment groups. The dry matter (DM) concentration in the empty body of kids increased as their age advanced, from 277 g/kg EBW (G0) to between 308 and 326 g/kg EBW (GI to GIV). The protein and fat concentration of LWGs increased with the level of feeding from GI (142 g crude protein (CP) and 75·5 g fat per kg LWG) to GIV (155 g CP and 109 g fat per kg LWG). Regression of energy retention (ER) on metabolizable energy (ME) intake resulted in an efficiency of ME utilization for body retention (k) of 0·72(± 006). ME requirement for maintenance was estimated as 458 kJ/kg M0·75 per day. Efficiency of nitrogen (N) utilization for growth and N requirement for maintenance were estimated as 0·66(±011) and 0·47 g/kg M0·75 per day, respectively.

Lysine requirement of 1.5–5.5 kg pigs fed liquid diets

An experiment was conducted to define the lysine requirement of neonatal pigs fed a liquid diet up to 5.5 kg bodyweight (BW). Neonatal pigs, 1–2 days old, with an initial bodyweight of 1.63 ± 0.04 kg, were randomly allotted to 10 isocaloric diets varying in lysine concentration from 0.76 to 1.62 g lysine/MJ gross energy (GE). Diets were formulated using whey protein concentrate and casein as protein sources and contained similar balance of indispensable amino acids. On day 1 of the experiment, pigs were fed 350 g liquid diet/kg metabolic bodyweight (BW0.75) according to the average BW of all pigs. On day 2, feeding rate was increased to 400 g/kg BW0.75. Increments were 100 g/kg BW0.75 per day for the subsequent 3 days until pigs reached 700 g/kg BW0.75 on day 5. Thereafter, feed was offered to pigs at a common feeding level of 700 g/kg BW0.75 each day until they reached 5.5 kg BW. Feed intake and BW were measured daily. Concentration of fat in the carcass decreased (P < 0.05) and the ratio of crude protein (CP) to fat in the carcass increased (P < 0.05) linearly as lysine inclusion increased. Both average daily gain and CP accretion increased (quadratic, P < 0.05), whereas fat accretion decreased (quadratic, P < 0.05) as lysine inclusion increased. Using the maximum point of the quadratic function, the estimated dietary lysine required for maximal growth (271 g/day) and CP accretion (45.2 g/day) was 1.41 and 1.32 g lysine/MJ GE, respectively. The dietary lysine required, estimating the requirement at the lower limit of the 95% confidence interval for CP accretion of 42.9 g/day, was 1.12 g lysine/MJ GE. Gross efficiency of CP deposition (CP deposition/CP intake) achieved a maximum of 0.85 at 1.01 g lysine/MJ GE.

Biochemical and physiological bases for utilization of dietary amino acids by young Pigs

Protein is quantitatively the most expensive nutrient in swine diets. Hence it is imperative to understand the physiological roles played by amino acids in growth, development, lactation, reproduction, and health of pigs to improve their protein nutrition and reduce the costs of pork production. Due to incomplete knowledge of amino acid biochemistry and nutrition, it was traditionally assumed that neonatal, post-weaning, growing-finishing, and gestating pigs could synthesize sufficient amounts of all "nutritionally nonessential amino acids" (NEAA) to support maximum production performance. Therefore, over the past 50 years, much emphasis has been placed on dietary requirements of nutritionally essential amino acids as building blocks for tissue proteins. However, a large body of literature shows that NEAA, particularly glutamine, glutamate, arginine and proline regulate physiological functions via cell signaling pathways, such as mammalian target of rapamycin, AMP-activated protein kinase, extracellular signal-related kinase, Jun kinase, mitogen-activated protein kinase, and NEAA-derived gaseous molecules (e.g., nitric oxide, carbon monoxide, and hydrogen sulfide). Available evidence shows that under current feeding programs, only 70% and 55% of dietary amino acids are deposited as tissue proteins in 14-day-old sow-reared piglets and in 30-day-old pigs weaned at 21 days of age, respectively. Therefore, there is an urgent need to understand the roles and dietary requirements of NEAA in swine nutrition. This review highlights the basic biochemistry and physiology of absorption and utilization of amino acids in young pigs to enhance the efficacy of utilization of dietary protein and to minimize excretion of nitrogenous wastes from the body.

Lysine requirements of pigs from 2 to 7 kg live weight

Thirty-two male pigs were used to investigate the effects of nine levels of dietary lysine ranging from 0·41 to 1·30 g lysine per MJ gross energy (GE) on the performance of pigs weaned at 1 to 2 days of age and growing between 2 and 7 kg live weight. The nine dietary lysine treatments, which contained similar levels of GE and balance of essential amino acids, were offered to the pigs at a common feeding level of 2·0 MJ GE per kg metabolic live weight (M075) per day. Growth performance and protein deposition rates increased linearly with increasing dietary lysine content up to about 0·97 g lysine per MJ GE and remained relatively constant thereafter. The response of protein deposition (PD, g/day) in the whole body of pigs to dietary lysine (L, g lysine per MJ GE) was described by three models. The respective regression equation for the quadratic function was PD = -14·23 + 87·66 L – 36·00 L2 and maximum protein deposition occurred at 1·22 g lysine per MJ GE. The rectilinear model, which had an ascending linear phase (PD = 1·49 + 40·10 L, R2 = 0·98, P < 0·001) and a horizontal component representing a mean protein deposition rate of 39·7g/day revealed that maximum protein deposition occurred at 0·95g lysine per MJ GE. Finally, application of the asymptotic model also revealed a highly significant equation: PD = 43·40 — 79·99 × 0·07111, R2 = 0·94, P < 0·001; which indicates a dietary requirement of 1·07 g lysine per MJ GE assuming that the dietary requirement was estimated at 0·90 of the asymptote maximal value. The results indicate that the dietary lysine requirement for pigs during the first 3 weeks of life appears to have changed little over the past 20 years despite substantial changes in genotype.

The effect of dietary concentrations of digestible energy on the performance and carcass characteristics of early-weaned pigs

Fifty-four pigs weaned at 3 weeks of age were allocated at an average weight of 5·4 kg to two experiments to examine the effects of diets having digestible energy (DE) concentrations ranging from 2910 to 3940 kcal/kg.

In the first experiment pig growth performance and the dry-matter digestibility of the experimental diets were measured between 3 and 8 weeks of age. The composition of the carcass at 8 weeks of age was correlated with the composition of various carcass joints.

In the second experiment pig growth performance was measured over the live-weight range 5-4 to 20 kg.

The findings were:

1. Growth rate was linearly related to DE intake.

2. The optimum DE level for maximum growth was 3640 kcal/kg.

3. The efficiency of utilization of DE for growth did not vary in the first experiment but was poorest at a DE concentration of 3245 kcal/kg in the second.

4. The DE content of the diet had no significant effect on carcass characteristics at 8 weeks of age in the first experiment or at 20 kg live weight in the second.

5. The proportion of fat and lean in the 8-week carcass was significantly (P < 0·01) correlated with that of the shoulder joint.

The influence of litter size on milk production of sows

Thirty sows were allocated at their first farrowing to five litter size treatments. Litter sizes of six, eight, 10,12 and 14 were established by cross-fostering within 48 h post partum. Milk yield (Y, kg/day) of sows was linearly related to litter size (L) and was described by the equations; Y = 5·98 (s.e. 0·48) + 0·689 (s.e. 0·046)L, R2 = 0·99; residual s.d. = 0·29; P < 0·001 and Y = 8·20 (s.e. 0·46) + 0·324 (s.e. 0·044)1, R2 = 0·95; residual s.d. = 0·28; P < 0·002 for early (day 10 to day 14) and late (day 24 to day 28) lactation, respectively. The composition of milk from sows suckling various litter sizes remained relatively stable but suckling frequency in early lactation increased linearly in response to increased litter size. Litter size significantly affected the average growth rate of individual piglets; piglet growth rate from birth to weaning at 28 days of age decreased from 283 g/day to 202 giday in response to increasing litter size from six to 14. The relationships between milk yield, average piglet growth rate and litter size indicate that the number of functional glands is the major factor influencing milk yield of sows. Increasing the number of functional glands by increasing litter size more than compensates for any decrease in milk output from individual glands.

The tissue and dietary protein and amino acid requirements of pigs from 8.0 to 20.0 kg live weight

Forty-three entire males were used to determine the pig's tissue requirements for protein and amino acids from 8·0 to 20·0 kg, and provide information on the capacity of diets formulated with conventional ingredients to contain the same levels and balances of amino acids as ideal protein to supply these nutrients. Seven diets with similar digestible energy (15·9 MJ digestible energy (DE) per kg) and crude protein concentrations from 119 to 232 g/kg (8·7 to 17·3 g lysine per kg) were offered ad libitum between 8·0 and 200 kg live weight. The rate of protein deposition was determined by comparative slaughter. The composition of the protein deposited in the whole empty body was determined from amino acid analyses of pigs killed at 8·0 kg and from the two extreme dietary treatments at 20·0 kg. Growth performance and the rates at which protein and lysine were deposited in the empty body increased linearly with increasing dietary protein concentration up to 187 g/kg and remained relatively constant thereafter. The corresponding dietary protein and lysine intakes required to support maximal protein accretion were 178 g/day (11·7 g/MJ DE) and 13·0 g/day (0·84 g/MJ DE) respectively. Based on the maximal deposition rates for protein (91·8 g/day), and lysine (5·96 g/day) and endogenous protein loss (77middot;6 g/day) estimated from the linear component of the relationship determined between protein deposition and apparent digestible protein intake, the pig's tissue requirements for protein and lysine were only 99·4 g/day (6·5 g/MJ DE) and 6·46 g/day (0·43 g/MJ DE) respectively. This disparity between the pig's tissue protein and amino acid requirements and the dietary levels needed to support these was associated with the fact that the apparent digestibility and biological value of the dietary protein were 0·92 and 0·602 respectively. Apart from small differences in the lysine content of body protein and the methionine: lysine ratio, the average amino acid composition of pigs killed at 8·0 kg, and from the diet of highest protein concentration at 20 kg, was similar to that of ideal protein, indicating that the low utilizability of dietary protein for tissue growth and maintenance was probably associated with low amino acid digestibility and/or availability. The implications of the results with respect to expression of the growing pig's requirements for protein and amino acids are discussed.

Maintenance of villous height and crypt depth in piglets by providing continuous nutrition after weaning

Thirty-two piglets weaned at 28 days of age were used to test the hypothesis that maintenance of nutrition after weaning would prevent the normal decline in villous height and increase in crypt depth and hence preserve the structure and function of the small intestine. Piglets were allocated to one of four treatments at weaning: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets offered ewes' fresh milk; and (4) piglets offered ewes' fresh milk plus 20 g t-glutamine per I. Piglets in treatments (3) and (4) were offered ewes' fresh milk every 2 h in a feeding schedule that increased from 1·2 I per piglet on the 1st day after weaning to 2·4 I on days 4 and 5. On the 5th day all piglets were killed and samples of small intestine were taken for histological and biochemical examination. Feeding ewes' milk or ewes' milk plus 20 g L-glutamine per I maintained (P > 0·05) villous height and crypt depth compared with piglets killed at weaning. In contrast, piglets given a dry starter diet had shorter villi (P < 0·001), deeper crypts (P < 0·001), and proportionately 0·21 to 0·28 less protein (P > 0·05) in their intestinal mucosa. Piglets given the starter diet proportionately grew from 0·49 to 0·62 more slowly (P < 0·01), ate the same amount of dry matter (DM; P > 0·05), but consumed proportionately 0·30 less energy (P < 0·001) than their counterparts given the milk diets. No treatment differences in the specific activity of lactase and sucrase were observed (P > 0·05). Significant correlations existed between voluntary food intake and villous height at the proximal jejunum for piglets given the starter diet and ewes' milk (P < 0·05 and P = 0·073, respectively). In turn, villous height was significantly correlated (r = 0·78 to 0·87, P < 0·05) with the rate of body-weight gain after weaning in these two groups. For piglets offered ewes' milk plus glutamine, an increase in DM intake was associated only with increases in crypt depth (P < 0·01). These data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain.

Growth, nutrient utilization, and body composition of dairy calves fed milk replacers containing different amounts of protein

Male Holstein calves < 1 wk of age were allowed a 2-wk adaptation period after purchase, and then were blocked by BW and assigned randomly within block to either a baseline slaughter group or one of four experimental groups (n = 8 to 9 per group). Treatments were isocaloric milk replacers (12.5% solids) fed at 12% of BW that contained 16.1, 18.5, 22.9, or 25.8% CP (DM basis) from whey protein sources. After a 6-wk feeding period, all calves were slaughtered and the weights and chemical composition of the viscera-free carcasses (VFC; including head, hide, feet, and tail) were determined. Gain of BW (0.38, 0.45, 0.56, and 0.62 kg/d) and gain:feed ratio (0.51, 0.59, 0.71, and 0.78) increased linearly (P < 0.001) as dietary CP increased; rate of change in body length, wither height, and heart girth also increased linearly (P < or = 0.05). Balance measurements conducted during wk 3 and 4 of the experimental period showed that both absorbed N (16.9, 20.0, 25.8, and 30.6 g/d) and retained N (7.6, 9.0, 13.2, and 15.6 g/d) increased linearly (P < 0.001) as dietary CP increased. Retained N as a percentage of absorbed N increased linearly (P < 0.01) as dietary CP increased (44.3, 44.7, 50.7, and 50.9%), whereas biological value was unaffected (71.1, 68.7, 69.5, and 67.3%; P = 0.26). Digestible energy and ME represented 94.5 and 89.7% of intake energy, respectively, and were not affected by dietary CP content. Plasma urea N concentration increased linearly (2.9, 3.3, 4.6, and 6.0 mg/dL) as dietary CP increased. Contents of water (68.2, 69.1, 70.2, and 70.5%; P < 0.001) and protein (19.6, 20.0, 20.0, and 20.2%; P < 0.10) in VFC increased linearly, whereas contents of fat (7.2, 6.2, 5.5, and 5.2%; P < 0.001) and ash (5.1, 5.2, 4.8, and 4.7%; P < 0.02) decreased linearly as dietary CP increased. Trends in visceral tissue composition were similar to those for VFC. The content of water in VFC tissue gain increased, whereas contents of fat and energy decreased, as dietary CP increased. Final VFC energy and gain of energy in VFC were not affected by dietary CP. At similar initial ME intakes, increasing dietary CP (i.e., increasing protein: energy) linearly increased ADG, gain:feed, N retention, and deposition of lean tissue in VFC, demonstrating that diet composition can markedly affect components of body growth in preruminant dairy calves.

Composition of Growth of Holstein Calves Fed Milk Replacer from Birth to 105-Kilogram Body Weight

Sixty calves were assigned to a comparative slaughter study to determine the changes in composition of milk replacer-fed Holstein bull calves from birth to 105-kg body weight (BW). Six calves were slaughtered on day of birth and served as a baseline for comparison of compositional changes. Fifty-four calves were assigned to one of three treatments (18 calves per treatment). Calves were fed milk replacer containing 30% crude protein (CP) and 20% fat. Target growth rates for treatments 1, 2, and 3 were 500, 950, and 1400 g/d, respectively. Six calves from each treatment were slaughtered and analyzed for energy, nitrogen, ether extract, and ash when they reached 65, 85 and 105 kg of BW. Actual daily gains from birth to slaughter were 560, 973, and 1100 g, and net deposition of CP and fat were 140 and 44, 204 and 154, and 247 and 161 g/d for treatments 1, 2, and 3, respectively. Results were used to develop equations to predict retained energy [retained energy = (empty BW(0.223)) x (empty BW gain(1.32))], and retained protein, [retained protein = (184 x empty BW gain (kilograms/d)) + (17.2 x (retained energy)/empty BW gain] where retained energy is in Mcal/d, retained protein is in g/d, and empty BW and gain are in kilograms. The composition of gain observed was compared to predictions from the 1989 Dairy NRC and 1996 Beef NRC equations and demonstrated the equations do not represent the composition of gain in calves of this weight.

Body composition of goat kids during sucking. Voluntary feed intake

The body composition of thirty-eight Granadina goat kids was measured. Six animals were slaughtered at birth while the remainder were kept individually at an environmental temperature of 24 +/- 2 degrees and a relative humidity of 60 +/- 5%. They were given goat's milk or a milk-substitute at two planes of nutrition until 15 or 30 d of age and then slaughtered. The goat's milk and milk-substitute contained 260.4 and 222.0 g digestible protein/kg and 23.23 and 20.85 MJ metabolizable energy/kg respectively. Voluntary feed intake as metabolizable energy was a function of metabolic body-weight (kg W0.75), equivalent to 2.42 and 2.44 times the energy requirement for maintenance for goat's milk- and milk-substitute-fed animals respectively. There was a high degree of correlation between the empty-body concentration of dry matter, fat and energy and empty-body-weight (P less than 0.001) or animal age (P less than 0.001), and between body-weight and animal age (P less than 0.001). The relationships between empty-body composition and empty-body-weight were independent of type of milk or plane of nutrition. In contrast relationships between empty-body composition or empty-body-weight and animal age were affected by the type of milk and, over all, by the plane of nutrition. All these results show that in these animals any body-weight will have a similar composition, but it will be reached earlier or later depending on dietary regimen and always with the limitation of voluntary intake.

Estimation of the intake of milk by lambs, from the turnover of deuterium- or tritium-labelled water

1. The total water turnovers of grazing ewes and their lambs were estimated on days 9, 23, 44, 69 and 86 of lactation from the dilution of tritiated water injected into the dam and deuterium oxide injected into the offspring. The contribution of milk to the total water turnover of the lambs was estimated at the same times from the accumulation of tritium in their body water. 2. Mean total water turnover in the ewes was 6.5 titres/d over the entire period. In lambs, total turnover rose from 1459 ml/d at 9 d to 2791 ml/d at 86 d, and was closely related to live weight (r2 0.760, P less than 0.001). The corrections to total water turnover, which were required because of the increasing body water pool size of the lambs during each measurement period, fell from + 10.6% at 9 d to + 3.7% at 86 d. All corrections were significant (P less than 0.001). 3. The intake of water as milk fell throughout the study, from 1501 ml/d at 9 d to 471 ml/d at 86 d. Pool-size corrections were significant (P less than 0.001). Milk intakes calculated from these results were 1816, 1054, 862, 742 and 588 ml/d at 9, 23, 44, 69 and 86 d of lactation. The rapid decline in milk intake reflected undernutrition of the ewes in early lactation. 4. The level of live-weight gain in early lactation was closely related to, and at a level expected from, the estimated milk intakes. From comparisons of estimated milk intakes with published estimates, it is concluded that the combined use of deuterium oxide and tritiated water results in accurate estimates of milk intake by the lamb throughout the ewe's lactation.

Nitrogen balance in relation to energy intake in entire male pigs weighing 75 kg

1. Nitrogen balance (NB) was determined in entire male pigs weighing 75.6 (SE 0.56) kg and given 1.43 MJ metabolizable energy (ME)/kg live weight (LW)0.75 per d of semi-synthetic liquid diets which varied in crude protein (N x 6.38):ME from 2.5 to 14.5 g/MJ. Maximum NB of 20.8 g/d was reached with diets containing at least 6.2 g protein/MJ ME. 2. The relation between energy intake and NB was then examined in pigs of comparable live weight (mean 73.8 (SE 0.39) kg) and receiving a liquid diet not limiting in protein. The diet, containing 10.0 g protein/MJ ME, was given at eight rates from 0.24 MJ ME/kg LW0.75 per d to ad lib. by approximately equal increments. Two animals were allocated to each level and two animals were fasted during the balance period. 3. The animals fed ad lib. achieved a mean intake of 1.84 MJ ME/kg LW0.75 per d. NB increased linearly as ME intake increased up to 27.6 MJ/d (1.096 MJ/kg LW0.75 per d) but thereafter remained constant at 22.8 g N/d.

Use of a nylon-bag technique for pig feed digestibility studies

1. The use of a nylon-bag technique for pig feed digestibility determination was studied. Bags, measuring 25 x 40 mm and containing feed samples, were introduced into the pig gastrointestinal tract through a duodenal cannula, and recovered in the faeces between 23 and 69 h later. The disappearance of organic matter and crude protein (nitrogen x 6.25) from the bags was compared with in vivo apparent digestibility, determined by conventional faecal-collection methods, and neutral-detergent-fibre content for eleven feeds. The residues left in the bags after passage through the intestine from whole-crop-pea (Pisum sativum) and barley-grain samples were analysed for starch, non-starch polysaccharide residues, Klason lignin, crude protein and ash. 2. Dry matter disappearance of barley or whole-crop peas was not influenced by increasing bag pore size from 10 to 36 microns or sample weight from 250 to 1000 mg. Pepsin (EC 3.4.2.1) pretreatment had no effect on the degradation in the bags of the feeds investigated. 3. Organic matter and crude protein disappearance from the bags exceeded in vivo apparent digestibility by up to 0.10 and 0.42 units respectively. In vivo apparent organic matter digestibility could be predicted (P less than 0.001) by the organic matter disappearance from the bags and the neutral-detergent-fibre content of the feed, while in vivo apparent crude protein digestibility was highly correlated (P less than 0.001) to all these indices but poorly to crude protein disappearance from the bags. 4. Klason lignin was the least degraded component measured in the whole-crop-pea and barley residues from the bags, while starch was completely digested.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of total and digestible lysine as a predictor of lysine availability in protein concentrates for young pigs

Forty pigs between 23 and 51 d of age were given, ad lib., diets containing 7.9 g lysine/kg. The diets contained wheat and one of five protein concentrates: milk, peanut (Arachis hypogaea) meal, cotton-seed (Gossypium herbaceum) meal, meat meal or lupins (Lupinus augustifolius). Twenty of the pigs were given an indigestible marker, 103Ru-labelled Tris-(1,10-phenanthroline)-ruthenium(II) chloride, between 51 and 56 d of age and were killed at 56 d of age. A further forty pigs, between 23 and 51 d of age, were given the same diets supplemented with 3 g L-lysine hydrochloride/kg. The weight gains of the pigs given the diets containing 7.9 g lysine/kg (95-153 g/d) were significantly less (P less than 0.05) than those of the pigs given the diets containing 10.9 g lysine/kg (274-340 g/d). Weight gains of pigs given the diets containing meat meal were less than those of pigs given diets containing milk, peanut meal or lupins. Feed conversion ratios decreased and N balances increased with increasing lysine content of the diets. Apparent digestibilities of dry matter (DM) and nitrogen of the diets containing meat meal and cotton-seed meal were less than those of the other three diets, but there was no effect of lysine content of the diets on these indices. The major site of DM and N absorption for the diet containing milk was the duodenum while for the other four protein concentrates the jejunum and ileum were the major absorption sites. Apparent digestibility of lysine from the five diets ranged from 0.54 to 0.75. The retention of the apparently absorbed lysine in weight gain was 0.86-0.94, and there was no significant (P greater than 0.05) difference between diets which suggested that the apparent digestibility of lysine could be an indicator of its availability.

The digestion of protein in young pigs and the utilization of dietary methionine

Forty pigs between 23 and 51 d of age were given ad lib. diets containing wheat and one of five protein concentrates: meat meal A, meat meal B, soya-bean meal, milk and lupins (Lupinus augustifolius). Twenty of these pigs were given indigestible markers from 51 to 56 d of age and were killed at 56 d of age. The diets containing meat meals A and B, soya-bean meal and milk contained 2.3 g total methionine/kg and the diet containing lupins contained 2.1 g/kg. A further forty pigs of the same age were given the same diets supplemented with 1 g synthetic methionine/kg. The weight gains and feed conversion ratios of the pigs given the diets containing 2.1-2.3 g methionine and 3.1-3.3 g methionine/kg were not significantly different. The weight gains of the pigs given lupins (2.1 g methionine/kg) were less than those of the pigs given the diets containing 2.3 g methionine/kg. The apparent digestibility of dry matter (DM) and nitrogen was less for the diets containing the meat meals (0.75 and 0.78 respectively) than for those containing the other protein concentrates (0.80 and 0.84). The retention times in the large intestine of the diets containing soya-bean meal and lupins were 965 and 1083 min which were greater than those of the diets containing the other protein concentrates, mean 732 min. The major site of N digestion and absorption for the diet containing milk was the area of the small intestine 25-50% of total length from the pylorus, while for the other protein concentrates the major site was 50-75% of its total length from the pylorus. The digestion and absorption of N in the large intestine was less (3.4%) for the diet containing milk than for those containing the other protein concentrates (7.5-11.3%). The apparent digestibility of the methionine to the ileum for the five diets ranged from 0.74 to 0.86 while the calculated retention of the apparently-absorbed methionine was 1.00. It was suggested that methionine digestibility could be used as an indicator of availability. The calculated retention of apparently absorbed N in the carcass was 0.71 for the pigs given the diet containing milk and 0.51-0.58 for the pigs given the other diets.

Digestion in the pig between 7 and 35 d of age. 6. The digestion of hydrolyzed milk and soya-bean proteins

1. Four pelleted diets were prepared containing milk or isolated soya-bean protein (ISP) as the major protein source. The milk and ISP were given either as intact proteins or partially (0.650 hydrolyzed with papain before feeding. 2. The diets were given ad lib. to thirty-two pigs from 7-28 d of age. The pigs were slaughtered at 28 d of age. 3. Weight gains, food conversion ratios and nitrogen balances of pigs given diets containing milk protein were better than those of diets containing ISP (231 g/d, 0.80 and 11.5 g/d compared to 209 g/d, 0.88 and 9.00 g/d respectively). 4. Partial hydrolysis of proteins before feeding did not affect the performance of the pigs. 5. Apparent digestibilities of N before the ileum and in the whole tract were 0.78 and 0.94 for the pigs given the ISP diets and 0.86 and 0.97 for the pigs given the milk-protein diets. 6. Retention time of ISP diets in the whole digestive tract was 1475 min and that of the milk-protein diets was 1089 min. 7. pH of digesta in the stomach was 5.0-5.3 for all diets and increased to 6.9-7.1 in the ileum. 8. There were no differences in flows of total N and protein N to the ileum and lower digestive tract between the pigs given the intact-and hydrolyzed-protein diets. 9. Apparent absorptions of N in the stomach, duodenum and jejenum were greater in the pigs given diets containing hydrolyzed proteins than in those given diets containing the intact proteins. 10. Flows of total N and protein N to the ileum tract were greater when the pigs were given the ISP diets than when they were given the milk-protein diets. 11. Hydrolysis of proteins before feeding resulted in a reduced trypsin and chymotrypsin activity in the duodenum and pancreas. 12. Retention of dietary N in the carcass was greater in pigs given the milk-protein diets (0.79) than in those given the ISP diets (0.68).

Digestion in the pig between 7 and 35 d of age. 5. The incorporation of amino acids absorbed in the small intestines into the empty-body gain of pigs given milk or soya-bean proteins

1. In two separate experiments, forty-two pigs weaned at 4--5 d of age were given diets containing milk or soya-bean protein and slaughtered at 7, 28 or 35 d of age. 2. The amino acid composition of the empty body of the pigs did not vary with age or sources of protein fed. 3. The nitrogen and amino acid contents of the empty body gain were calculated between 7 and 28, and 7 and 35 d of age. The retention of absorbed N was greater in pigs given a soya-bean meal (SBM) diet than in pigs given milk or isolated soya-bean protein (ISP) diets. 4. The retention of total absorbed N was greater in pigs given a pelleted milk diet (0 .72) than in pigs given a liquid milk diet (0 . 58). 5. Methionine and threonine appeared to be the first two limiting amino acids, as indicated by their high incorporation into the empty body, for pigs given soya-bean proteins in Expt 3, while methionine and lysine were the first two limiting amino acids for pigs given ISP in Expt 4. 6. The addition of methionine to diets in Expt 3 reduced the retention of absorbed methionine in the empty body by 43--76%. Lysine supplementation did not alter the retention of the absorbed lysine. 7. Retention of arginine, proline and glycine in the body was greater than the apparent absorption of each of these amino acids.