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Pigs immunized against gonadotropin-releasing factor (GnRF) have increased carcass fatness compared to entire males; however, the timing of this increase in fatness after the second immunization against GnRF has not been determined. An experiment was conducted to identify and compare the growth performance, body composition, and physiological changes in immunocastrated males (IC males) at different BW and feeding levels. A total of 64 pigs were used in a 2 × 2 × 2 factorial experiment with the treatments being 1) sex (entire males or IC males), 2) initial BW (45.9 kg [light] or 78.3 kg [heavy]), and 3) feeding regime (2.5 times maintenance [restricted] or ad libitum). The pigs were individually housed, and the diets were fed for 4 wk after the second immunization against GnRF until slaughter at either 68.4 kg BW (light) or 105.8 kg BW (heavy). Immunocastrated males on a restricted feed intake had a lower ADG compared to entire males from d 15 to 28 and d 0 to 28 ( 0.011 and 0.011, respectively). Fat deposition was not affected by sex from d 0 to 14, but from d 15 to 28 IC males deposited 45 g/d more fat than entire males ( = 0.025). Immunocastrated male pigs fed ad libitum deposited 87 g/d more fat from d 15 to 28 than entire males fed ad libitum ( = 0.036). However, there was no difference in fat deposition between IC males and entire males when feed intake was restricted from d 15 to 28. Plasma urea nitrogen levels were greater in IC males compared to entire males from d 7 after the second immunization against GnRF ( 0.05 for d 7, 10, 14, 21, and 28). Plasma concentrations of IGF-1 were lower for IC males compared to entire males on d 3, 7, 10, and 28 ( 0.05 for all days). The following conclusions were made: 1) when pigs are immunized at a light BW (50 kg) and/or are on a restricted feed intake, they have a reduced propensity to deposit fat; however, the restriction in feed intake adversely affects growth rate. 2) The majority of fat deposition for males immunized at heavy BW (80 kg) occurs from d 15 to 28 after the second immunization against GnRF.

An experiment was conducted to determine the standardized ileal digestible (SID) Lys requirement of entire male and male pigs immunized against gonadotrophin releasing factor (GnRF; immunocastrates). A total of 420 entire male and immunocastrated (IC) male pigs weighing 60.1 kg BW (SEM 0.49) were used in a 2 × 5 factorial experiment with the main effects being gender (entire males or IC males) and 5 concentrations of SID Lys:DE ratio (0.32, 0.43, 0.54, 0.64, or 0.75 g SID Lys/MJ DE). The diets were fed for 6 wk until slaughter at 107.5 kg BW (SEM 5.72). Over the entire period, IC males had a greater ADG ( < 0.001), greater ADFI ( < 0.001), and lower G:F ( < 0.001) compared with entire males. Immunocastrated males had increased plasma urea nitrogen (PUN) concentrations compared with entire males from d 10 to 42 ( < 0.001 for all days). Plasma urea nitrogen concentration also increased as Lys concentrations increased from d 3 to 42 ( < 0.001 for all days). Using the linear-plateau model, the optimal ADG for entire males was achieved at SID Lys concentrations of 0.68, 0.62, 0.54, and 0.58 g/MJ DE whereas optimal G:F was achieved at SID Lys concentrations of 0.72, 0.60, 0.54, and 0.51 g/MJ DE for the time periods d 0 to 14, d 15 to 28, d 29 to 42, and d 0 to 42, respectively. For IC males, optimal ADG was achieved at SID Lys concentrations of 0.64, 0.43, 0.38, and 0.40 g/MJ DE whereas optimal G:F was achieved at SID Lys concentrations of 0.64, 0.43, 0.36, and 0.42 g/MJ DE for the same respective time periods. Using the quadratic polynomial model, maximum ADG for entire males was achieved at SID Lys concentrations of 0.62 and 0.58 g/MJ DE whereas maximum G:F was achieved at SID Lys concentrations of 0.59 and 0.68 g/MJ DE for d 29 to 42 and d 0 to 42, respectively. For IC pigs, maximum ADG was achieved at SID Lys concentrations of 0.69, 0.54, and 0.64 g/MJ DE whereas maximum G:F was achieved at SID Lys concentrations of 0.81, 0.54, and 0.64 g/MJ DE for d 0 to 14, d 29 to 42, and d 0 to 42, respectively. A solution could not be found using the quadratic polynomial model for entire males for d 0 to 14 for both ADG and G:F and for both entire males and IC males for d 15 to 28 within the range of Lys values tested. When both the growth performance and PUN values are considered, the results suggest that IC males show a response to dietary SID Lys similar to that of entire males for 2 wk after the second immunization against GnRF. After this, IC males have a lower requirement for SID Lys than entire males.

A 4 × 3 factorial experiment (n=8 pigs per treatment combination) was conducted with 96 female Landrace × Large White pigs to examine the required level of dietary vitamin E and optimum feeding duration before slaughter to maximise muscle vitamin E content in the Longissimus thoracis et lumborum (LTL) muscle. The respective factors were four dietary levels of vitamin E (supplemented as dl-α-tocopheryl acetate; 35, 300, 500, and 700 IU/kg) and three feeding durations (14, 28 and 42 days before slaughter). Vitamin E concentration in the LTL was maximised at 6 mg/kg, which was achieved by feeding a 700 IU vitamin E diet for 28 days before slaughter (P<0.001). There was no further increase in the vitamin E content of the LTL by feeding the high vitamin E diet more than 28 days before slaughter., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study tested the hypothesis that vitamin E (Vit E) and omega-3 fatty acids will additively attenuate the production of proinflammatory cytokines and PGE2 in immune system–stimulated growing–finishing pigs. A total of 80 mixed sex pigs weighing 50.7 ± 0.76 kg (mean ± SE) were blocked and stratified based on sex and BW to a 2 × 2 factorial design with the respective factors being 1) without and with 300 IU Vit E and 2) without and with 25% replacement of tallow to linseed oil as a source of n-3 fatty acids. Each treatment consisted of 4 replicate pens with 5 pigs (3 barrows and 2 gilts) per pen. All pigs were challenged with an intramuscular injection of Escherichia coli lipopolysaccharide (LPS; O111:B4) twice weekly over the 6-wk experiment. After LPS challenge, pigs fed a diet supplemented with n-3 fatty acids had fewer (P < 0.05) white blood cells and tended to show both a reduced (P < 0.10) proportion of lymphocytes and IgG concentration compared with pigs fed a diet without any supplements. Supplementation of n-3 fatty acids reduced (P < 0.01 and P < 0.05) serum concentrations of cortisol and tumor necrosis factor α (TNF-α), respectively. The serum concentration of PGE2 was decreased (P < 0.05) with supplementation of both Vit E and n-3 fatty acids; however, the extent of the reduction was greater (P < 0.001) in pigs fed an n-3 fatty acid–supplemented diet. However, there were no additive effects of the combined supplementation of Vit E and n-3 fatty acids on serum concentrations of proinflammatory cytokines and PGE2. The results suggest that n-3 fatty acids independently attenuate production of TNF-α and PGE2 in immune system–stimulated growing–finishing pigs.

A split plot experiment with 72 male pigs weighing 52.9 ± 0.39 kg (mean ± SEM) was conducted to examine AA partitioning and body protein deposition (PD) in response to increasing dietary sulfur amino acids (SAA) with or without immune system (IS) activation. The main plot was with and without IS activation, and 4 diets containing different amounts of standardized ileal digestible (SID) SAA (SAA to Lys ratios of 0.45, 0.55, 0.65 and 0.75) were the subplots. Activation of IS was achieved by intramuscular injection of Escherichia coli lipopolysaccharides (LPS; serotype 055:B5, Sigma; 30 μg/kg BW) every Monday and Thursday, with control pigs injected with sterile saline. Maximum body PD, measured by dual-energy X-ray absorptiometry (DXA), and minimum plasma urea content were achieved at SID SAA:Lys ratio of 0.55 in saline-injected pigs but were achieved at a SID SAA:Lys ratio of 0.75 in IS-activated pigs. Immune system activation increased rectal temperature (P < 0.05), plasma haptoglobin (1.1 vs. 2.0 mg/mL; P < 0.001), and the proportion of neutrophils (0.39 vs. 0.42; P < 0.05) and decreased serum albumin content (38.4 vs. 36.8 g/L; P < 0.01). Increasing dietary SAA had no effects on these variables. Immune system-activated pigs had lower levels of homocysteine (Hcy; P < 0.001) and a lower Ser content (P < 0.05). Results showed that increasing dietary SAA as DL-methionine in growing and/or finishing pigs altered plasma AA contents, and that use efficiency of the AA was improved when greater levels of SAA were supplemented in IS-activated pigs.

Forty-two individually housed entire male pigs weighing 37.5 ± 0.15 kg (mean ± SEM) were used in a randomized block design having 7 dietary treatments (n = 6). The dietary treatments were 5 semisynthetic diets containing 350 g/kg of soybean (Glycine max) meal (SBM) with variable heat treatments (0, 7, 14, 21, and 28 min autoclaved at 135°C), a protein free (N-free) diet, and an enzymatically hydrolyzed casein (EHC) diet. Heat treatment linearly decreased (P < 0.001) total Lys content from 27.5 to 19.2 g/kg and reactive Lys content from 23.4 to 11.7 g/kg. Apparent, standardized, and true ileal digestible total and reactive Lys contents linearly decreased (P < 0.001) with increasing severity of heat treatment and were accurately predictable (P < 0.001) from total and reactive Lys content in heat-damaged SBM. These data indicate that excessive heat processing of SBM reduced both the content (P < 0.001) and digestibility (P < 0.001) of total and reactive Lys in SBM.

The objective of this study was to evaluate whether altering the timing of the secondary anti-gonadotropin-releasing factor (GnRF) immunization closer to slaughter in male finishing pigs would reduce the increase in P2 fat depth (6.5 cm from the midline over the last rib), while still limiting the incidence of boar taint. Entire male pigs are immunized against GnRF to reduce the concentration of testicular steroids that in turn limits the incidence of boar taint. Additionally, testicle measurements and color measurements were taken to examine whether they could be used to differentiate nonimmunized entire males from immunized male pigs. A total of 175 Large White × Landrace entire male pigs aged 16 wk (59 kg of BW) were used in a completely randomized design with 5 treatment groups based on the time that pigs received the secondary immunization before slaughter. Pigs were housed in groups of 7 and randomly allocated to 1 of 5 treatments with 5 replicates per treatment. The treatment groups were as follows: no secondary immunization before slaughter, and the secondary immunization given at 2, 3, 4, or 6 wk before slaughter. The P2 fat depth levels were reduced (P = 0.054) with the secondary immunization closer to slaughter (11.7, 11.3, 12.8, 12.6, and 13.7 mm for no secondary immunization, secondary immunization at 2, 3, 4, and 6 wk before slaughter, respectively). Androstenone concentration did not exceed the generally accepted industry sensory threshold of 1.0 µg/g of fat, and both androstenone concentration in the adipose tissue and testosterone concentrations in the blood were suppressed (P < 0.001) in all immunized pigs regardless of timing of the secondary immunization compared with pigs that did not receive the secondary immunization. Skatole concentration of all pigs in the experiment did not exceed the generally accepted industry sensory threshold of 0.2 µg/g. Testes weight was reduced (P < 0.001) with increased time between slaughter and the secondary immunization. Immunized pigs, regardless of time before slaughter, had greater L* (lightness) and b* (yellowness) color of the testicle surface (P < 0.001 and P = 0.020, respectively), and less a* (redness) color compared with entire males (P < 0.001). The study provides further evidence of the efficacy of the anti-GnRF immunization and indicates that the secondary immunization can be moved closer to slaughter, while still limiting the incidence of boar taint. Testicle measurements and color measurements together could provide a method of discrimination between carcasses from immunized entire males clear of boar taint and tainted carcasses.

This study evaluated the effect of feeding low protein (LP) diets for 7 or 14 d after weaning or a high protein (HP) diet for 14 d after weaning on postweaning diarrhea (PWD), indices of protein fermentation, and production in pigs infected or not infected per os with an enterotoxigenic strain of Escherichia coli. A total of 72 female pigs weaned at aged 21 d with initial BW of 5.9 +/- 0.12 kg were used in a 3 x 2 factorial arrangement of treatments. The factors were 3 feeding regimens associated with different combinations of feeding duration and diet CP level: (i) HP diet (256 g of CP/kg) fed for 14 d after weaning, (ii) LP diet (175 g of CP/kg) fed for 7 d after weaning, and (iii) LP diet fed for 14 d after weaning; and infection or noninfection with an enterotoxigenic strain of E. coli (10(7) cfu/mL, serotype O149:K91:K88) at 72, 96, and 120 h after weaning. The LP diets were fortified with crystalline Ile and Val to achieve an ideal AA pattern. A second-stage diet (213 g of CP/kg) was fed to pigs at the conclusion of each feeding regimen, and the study finished 4 wk after weaning. None of the diets contained antimicrobials. Feeding the LP diets decreased (P < 0.001) plasma urea nitrogen, fecal ammonia nitrogen concentrations, and the incidence of PWD, but increased (P = 0.001) fecal DM content compared with pigs fed HP in the 2-wk period after weaning. Infection increased shedding of beta-hemolytic E. coli (P < 0.001), the incidence of PWD (P < 0.001), and fecal ammonia nitrogen concentrations (P < 0.01), but did not interact with feeding regimen, after weaning. Pigs challenged with E. coli grew more slowly (P < 0.001) and had decreased G:F (P < 0.01) compared with nonchallenged pigs in the 4-wk period after weaning. Feeding an LP diet for 7 or 14 d after weaning markedly reduced the incidence of PWD after infection with beta-hemolytic E. coli. Infection was associated with decreased indices of protein fermentation in the distal gastrointestinal tract but did not compromise the growth of weaner pigs in the 4-wk period after weaning.

Sixty-three male pigs (Landrace x Large White) weighing 49.5 +/- 0.40 kg were used to (1) examine the variation in DE content of Lupinus angustifolius L. in relation to variety and geographical growing region and (2) establish prediction equations for DE content from physical and chemical composition. The pigs were randomly allocated to a 4 x 2 factorial treatment design with respective factors being 4 varieties (cv. Belara, Coromup, Mandelup, and Tanjil) and 2 growing locations (northern and southern agricultural areas of Western Australia). In addition, a wheat control diet was fed as a reference for calculation of lupin DE content. The lupins were ground through a hammer mill fitted with a 4-mm screen to a mean particle size of 888 mum. Pigs were fed their respective experimental diets at 3 times maintenance energy level [3 x (0.458 x BW(0.75))/diet DE] in the study. The DE content of lupins ranged from 13.3 to 15.7 MJ/kg with a mean value of 14.2 MJ/kg. Variety of lupins affected (P < 0.01) the DE content, and lupins grown in the northern agricultural region had a greater DE content than the same lupins grown in the southern agricultural area (P < 0.01). Although the variation in DE content of lupins was mostly caused by significantly greater DE content of cv. Coromup grown in the northern agricultural region, the results suggest that genetic and environmental conditions during the growth of lupins have a significant impact on the utilization of energy in grower pigs. Simple regression analysis showed that prediction of DE content was possible from the proportion of hulls [R(2) = 0.88, residual SD (RSD) = 1.116, P < 0.001], 1,000-seed weight (R(2) = 0.77, RSD = 1.092, P < 0.01), and soluble arabinoxylan content (R(2) = 0.64, RSD = 1.072, P < 0.05). Multiple regression analysis showed that adding total nonstarch polysaccharide (R(2) = 0.96, RSD = 1.187, P < 0.01) and soluble nonstarch polysaccharide (R(2) = 0.95, RSD = 1.200, P < 0.01) to the equation along with the proportion of hull and 1,000-seed weight significantly improved the accuracy of prediction. Results indicate that the DE content of lupins varies by up to 2.4 MJ/kg and that the DE content can be predicted with a good degree of accuracy using physical and chemical characteristics.

Two experiments were conducted to examine the effects of lupin particle size on amino acid (AA) and energy digestibility and fermentation characteristics in pigs. Expt 1 examined the effects of lupin variety (cv. Tanjil and Mandelup) and lupin particle size (746, 888, 1099 and 1136 mum) on the total-tract apparent digestibility of dietary components in 63.5 (sd 7.28) kg pigs. While variety had no effect on total-tract apparent digestibility, decreasing particle size of lupins linearly increased total-tract apparent digestibility of crude protein of diets containing 350 g lupins per kg (P < 0.01). Expt 2 examined the effect of lupin particle size (567, 995, 1198, 1250 and 1304 mum) on digestion and fermentation characteristics in 29.8 (sd 2.9) kg pigs. Pigs were fed the respective diets ad libitum for the first 2 weeks and fed at three times maintenance energy level in the third week. Pigs were euthanised under sedation at 46.7 (sd 4.21) kg to collect digesta samples along the intestinal tract. Decreasing particle size increased apparent ileal and total-tract digestible N (P < 0.01) and the apparent and standardised ileal digestible AA content (P < 0.05- < 0.001) of lupins. Decreasing particle size of lupins linearly decreased the molar proportion of straight-chain volatile fatty acids (sum of acetic, propionic and butyric acids; VFAAPB), while branched-chain fatty acids (sum of valeric, caproic, isobutyric and isovaleric acids) were linearly increased (P < 0.001). The results demonstrated that particle size of lupins is a critical factor influencing nutrient, especially AA, utilisation efficiency and fermentation characteristics in the gastrointestinal tract of pigs.

An experiment was conducted to examine the effect of continual fluctuations in feed intake on grower-finisher pig growth performance and carcass fat-to-lean ratio (F:L). Sixty individually housed female pigs (Landrace x Large White) with initial BW of 29.8 +/- 0.4 kg were randomly allocated to 1 of 4 feeding regimens (n = 15): 1) ad libitum throughout (AL); 2) 85% of the mean intake of the AL group during the previous week (R); 3) 70% of the mean intake on 1 d, and on the following day, 100% of the amount consumed by the AL group during the preceding week, with this pattern repeated every 2 d throughout (D); and 4) 70% of the mean intake for 3 consecutive days, and 100% of the amount consumed by the AL group for the next 3 d, with this pattern repeated throughout the experiment (3-D). Pigs receiving each treatment were fed the same diets during the weaner (10 to 20 kg), grower (20 to 50 kg), finisher 1 (50 to 70 kg), and finisher 2 (70 kg to slaughter at approximately 104 kg) growth phases. Pigs receiving fluctuated feed intake either by the D or 3-D feeding regimen showed a pattern of growth similar to that of pigs on the R feeding regimen. Pigs on the R and 3-D regimens were lighter at 28 d (P < 0.05) and pigs on the R, D, and 3-D regimens were lighter at 63 d (P < 0.05) than pigs on the AL regimen. Pigs on the R, D, or 3-D feeding regimens had a greater G:F between 15 to 42 d of the experiment than pigs fed AL throughout (P < 0.05). The R, D, and 3-D feeding regimens seemed to have some effect on carcass weight and dressing percentage, and pigs had a decreased P2 (located 65 mm from the midline of the carcass at the last thoracic rib) backfat depth (P < 0.05) compared with pigs fed AL. Pigs on the AL and 3-D feeding regimens had thicker subcutaneous fat at the last lumbar vertebrae on the dorsal edge of the loin than pigs on the R feeding regimen (P < 0.05). Carcass and visceral fat content and the F:L in the carcass and primal cuts, as measured by dual energy x-ray absorptiometry, were not different among treatments. However, pigs on the AL and 3-D feeding regimens had decreased estimated bone content in the carcass compared with pigs on the R and D feeding regimens (P < 0.05). The results indicated that continual fluctuation in feed intake either every other day or every 3 d had minimal effects on growth and carcass F:L compared with pigs fed the same restricted amount throughout the experiment.

This study evaluated the effects of feeding pigs low protein (LP) diets for different lengths of time after weaning on indices of protein fermentation, the incidence of postweaning diarrhoea (PWD), growth performance, and total-tract apparent digestibility. Sixty weaner pigs weighing 6.1 +/- 0.13 kg (mean +/- SEM) were used in a completely randomised design having five treatments: (i) a high protein diet (HP, 243 g/kg CP) fed for 14 d after weaning (HP14); (ii) a low protein diet (LP, 173 g CP/kg) fed for 5 d after weaning (LP5); (iii) LP diet fed for 7 d after weaning (LP7); (iv) LP diet fed for 10 d after weaning (LP10), and (v) LP diet fed for 14 d after weaning (LP14). All diets were supplemented with lysine, methionine, tryptophan and threonine, with all LP diets additionally fortified with crystalline isoleucine and valine to conform to a proposed ideal amino acid (AA) pattern. A second-stage diet (215 g CP/kg) was fed to pigs at the conclusion of each treatment. None of the diets contained antimicrobial compounds. Feeding a LP diet, regardless of duration of feeding, decreased plasma urea nitrogen (p < 0.001) and faecal ammonia-nitrogen (p < 0.001) contents. Feeding a LP diet, irrespective of feeding duration, decreased the incidence of PWD at day 8 after weaning (p = 0.044), and pigs fed diets LP7, LP010 and LP14 had firmer faeces (p = 0.030, p = 0.047 and p = 0.007, respectively) between days 10 and 12 after weaning. Treatments LP5, LP7, LP10 and LP14 did not reduce (p > 0.05) growth performance up to 106 days after weaning compared to pigs fed the HP diet. Total-tract apparent digestibility of dry matter, energy and crude protein were similar (p > 0.05) between treatments. Our data suggest that feeding a LP diet, supplemented with AA to conform to an ideal AA pattern, for 7-10 days after weaning can reduce PWD in pigs fed antibiotic-free diets without compromising production.

The experimental objectives were to verify whether a qualitative measure of creep feed consumption using a dye was related to performance, and associate this with teat order. Indigo carmine (5 g/kg) was added to a starter diet between days 12 and 31 (weaning) of lactation. On days 19, 23, 27 and 31, faeces from each piglet were assessed for colouration. Each piglet was categorized as a 'good', 'moderate' or 'small/non' eater of feed. There were no differences in pre-weaning growth rate between categories. Piglets classed as 'good' or 'moderate' eaters in lactation grew fastest (p = 0.009) in the first three days after weaning, but between days 4 and 7, the highest growth rate occurred in 'moderate' eaters. 'Small/ non' eaters grew slower (p < 0.01) between weaning and 28 days after weaning. Piglets drinking milk from anterior teats were heavier at weaning (p < 0.001) and for the first 14 days after weaning (p = 0.104) compared to piglets sucking posterior teats. Data from this study demonstrated that creep feed intake of piglets could qualitatively be assessed using indigo carmine, and that this categorization was related to performance in the immediate post-weaning period.

Sources of viscous soluble fibre, such as barley and oats, have often been included in the weaning diet of the pig to accelerate development of the large intestine. Inclusion of a non-fermentable, viscous compound, sodium carboxymethylcellulose (CMC), in a low-fibre weaning diet was tested to assess the influence of digesta viscosity on the gut in the absence of increased fermentation. Two CMC sources, of low and high viscosity, were added to cooked rice-based diet at 40 g/kg total diet. A third control rice diet did not contain any CMC. Diets were fed for 13 d following weaning at 3 weeks of age. Addition of CMC to the diet significantly increased the intestinal viscosity of digesta within the small (P<0.001) and large (P<0.05) intestine. No simple association was found between increases in intestinal viscosity and effects on intestinal morphology and whole-body growth. The average empty-body-weight gain and the small intestinal villus height increased with low-viscosity CMC, but decreased with the high-viscosity CMC group. The full large intestinal weight increased in all pigs fed CMC. Dietary CMC (both low- and high-viscosity) increased the percentage moisture of digesta and faeces, and was associated with increased faecal shedding of enterotoxigenic haemolytic Escherichia coli. Feed ingredients in weaning diets that excessively increase the viscosity of the intestinal digesta may be detrimental to pig health and production.

Sows that were either fat or lean at farrowing (340 or 280 g of body fat/kg BW, respectively) were offered either a low-protein (LP; 7.9% CP and 15.5 MJ DE/kg as fed) or a high-protein (HP; 19.0% CP and 15.6 MJ DE/kg as fed) diet on an ad libitum basis throughout a 4-wk lactation to test the hypothesis that the amount of milk and its composition are responsive to the supply of endogenous (body reserves) and exogenous (diet) substrates. Pigs were weighed at birth and weekly during lactation, milk yield was estimated using deuterium oxide in early (d 4 to 8) and late lactation (d 24 to 28), and milk samples were collected to determine composition in early (d 4 to 6) and late lactation (d 25 to 27). Throughout lactation, milk yield and composition were mainly associated with differences in litter size. Milk yield was about 15% higher in lean than in fat sows and in sows fed HP rather than LP, but large CV (17 to 32%) prevented these differences from attaining significance (P > .273). The responses in milk yield were reflected in pig growth. Differences in milk composition between treatment groups were not significant; however, during early lactation there was a tendency for fat sows to produce milk with a fat content 21% higher, and a protein content 12% lower, than that of lean sows. Changes in the protein:energy ratio of milk during the course of lactation and small changes in milk yield composition collectively suggested that in early lactation, sow body composition affected milk production but, as lactation progressed, the dietary supply of precursors for milk synthesis became more important.

We used 35 primiparous sows to investigate the link between body fatness at farrowing and voluntary feed intake (VFI) during lactation. Two groups of sows were fed differently throughout gestation (either 2.3 kg/d of a diet containing 5.8% CP and 14.6 MJ DE/kg as fed or 1.7 kg/d of a diet containing 15.6% CP and 14.5 MJ DE/kg as fed) so that they commenced lactation at a similar body weight (158 to 152 kg) but with different body compositions: either 340 (fat) or 280 (lean) g of body fat/kg BW (P < .001). During lactation, sows were offered either a low-protein diet (7.9% CP and 15.5 MJ DE/kg as fed) or a high-protein diet (19.0% CP and 15.6 MJ DE/kg as fed) on an ad libitum basis. During lactation, VFI was measured daily, and sow body weight and backfat were measured weekly. Blood samples were collected from sows on d 110 of gestation and d 14 and 28 of lactation, and plasma was analyzed for NEFA, glycerol, insulin, glucose, and beta-hydroxybutyrate. Fat sows ate 30% less than their lean counterparts during lactation (P < .001), which corresponded to a 70% higher concentration of NEFA in plasma (P = .01) and a 30% higher concentration of glycerol (P = .15). The VFI during the first 2 wk of lactation was affected only by body fatness and not by the protein content of the lactation diet. The dietary supply of protein influenced VFI during wk 3 and 4 of lactation, possibly by affecting milk production and hence the drive to consume feed. Weight loss, particularly lean tissue loss, was minimized by feeding the high-protein diet during lactation (P < .002).

Two experiments were conducted to test the hypothesis that feeding diets which limit the amount of fermentable substrate entering the large intestine would protect pigs against experimental infection with Serpulina hyodysenteriae, the causative agent of swine dysentery. Experiment 1 examined the effect of grain processing (hammer milling vs. steam flaking) and grain type (barley, groats, corn, sorghum and wheat) on indices of fermentation in the large intestine and the incidence of swine dysentery. Experiment 2 examined the role of five diets, steam-flaked corn, steam-flaked sorghum, hammer-milled wheat, extruded wheat and cooked white rice, on these same measures. All diets contained an animal protein supplement and no antibiotics. Pigs fed diets based on steam-flaked corn and steam-flaked sorghum had a lower incidence of disease (11-33%) than pigs fed diets based on other grains (75-100%). Pigs fed the diet based on cooked white rice were fully protected against swine dysentery. Both the soluble non-starch polysaccharide (NSP) concentration and the total NSP concentration of the diets explained a significant proportion of the variation in swine dysentery (R2 = 0.56, P = 0.016, and R2 = 0.71, P = 0.002, respectively), such that pigs eating diets containing <1.0 g/100 g soluble NSP showed reduced disease. However, pigs fed corn, sorghum and steam-flaked sorghum (Experiment 2), which contained only 0.4-0.5 g/100 g soluble NSP, still had a high incidence of disease (>50%). This was attributable to a higher level of resistant starch present in these grains. These data provide evidence that the expression of swine dysentery is associated with an increased concentration of fermentable substrate entering the large intestine.