Growth performance and nutrient digestibilities in nursery pigs receiving varying doses of xylanase and ß-glucanase blend in pelleted wheat- and barley-based diets.

In 2 experiments, dose response efficacy of a xylanase and ß-glucanase blend (XB) on growth performance and ileal nutrient digestibility was investigated in nursery pigs fed pelleted wheat (Triticum aestivum)- and barley (Hordeum vulgare)-based diets. A basal diet (meeting NRC [1998] specifications for 6 to 30 kg BW, except for 5% lower DE) was supplemented with XB to give 4 diets (0, 50, 100, and 200 g/t). The xylanase and ß-glucanase blend was formulated to contain guaranteed activity of 12,200 and 1520 units/g, respectively. In Exp.1, 192 nursery pigs (initial BW of 6.5 kg) were randomly assigned to 4 diets to give 12 pens (4 pigs/pen) per diet to study growth performance for 42 d. In Exp. 2, apparent ileal digestibility (AID) of energy and AA was evaluated in 4 individually housed ileal-cannulated barrows (21 kg BW) according to a 4 × 4 Latin square design. In Exp. 1, XB linearly and quadratically increased (P < 0.05) G:F compared with control. Adding 200 g/t increased overall G:F by 20% compared with control. In Exp. 2, XB linearly increased (P < 0.05) AID of DM, CP, energy, and AA. In conclusion, supplemental xylanase and ß-glucanase in nursery pelleted wheat- and barley-based diets deficient in DE increased energy and nutrient use, resulting in better G:F. In conclusion, an enzyme product containing a combination of xylanase and ß-glucanase allowed young pigs to derive more nutrients and energy in a wheat- and barley-based diet deficient in energy.

Degradation and fermentation characteristics of wheat coproducts from flour milling in the pig intestine studied in vitro.

Use of wheat (Triticum aestivum) flour milling coproducts (WFM) in pig diets may ameliorate high feed cost. However, digestibility of WFM is lower than feed grains, and limited information exists about their fermentation characteristics. In vitro degradation and fermentation characteristics of 6 WFM samples (2 Shorts, 2 Millrun, middlings, and bran) with varying fiber and protein contents were studied. After a pepsin-pancreatin hydrolysis, WFM were incubated in a buffer solution with minerals and fresh pig feces as inoculum. Accumulated gas production was measured for 72 h and modeled. The VFA concentration was measured in the fermented solutions. The DM degradability during fermentation ranged from 31 to 52% and correlated negatively with ADF (r = -0.65; P < 0.01) and positively with CP (r = 0.50; P < 0.01) content of WFM. Total gas production ranged from 101 to 148 mL/g DM incubated and was negatively correlated with ADF and crude fiber (r = -0.70 and -0.59, respectively; P < 0.01). The VFA production ranged from 2.0 to 3.0 mmol/g and the fractional rate of degradation ranged from 0.08 to 0.11/h. In conclusion, fiber components were associated with degradability and fermentability of WFM. Therefore, treatments targeted to reduce the impact of fiber and protein may increase the digestibility and fermentability of wheat coproducts from flour milling.

Effects of individual or combined xylanase and phytase supplementation on energy, amino acid, and phosphorus digestibility and growth performance of grower pigs fed wheat-based diets containing wheat millrun.

The objective of these studies was to determine if dietary enzymes increase the digestibility of nutrients bound by nonstarch polysaccharides, such as arabinoxylans, or phytate in wheat millrun. Effects of millrun inclusion rates (20 or 40%), xylanase (0 or 4,375 units/kg of feed), and phytase (0 or 500 phytase units/kg of feed) on nutrient digestibility and growth performance were investigated in a 2 x 2 x 2 factorial arrangement with a wheat control diet (0% millrun). Diets were formulated to contain 3.34 Mcal of DE/kg and 3.0 g of true ileal digestible Lys/Mcal of DE and contained 0.4% chromic oxide. Each of 18 cannulated pigs (36.2 +/- 1.9 kg of BW) was fed 3 diets at 3x maintenance in successive 10-d periods for 6 observations per diet. Feces and ileal digesta were collected for 2 d. Ileal energy digestibility was reduced (P < 0.01) linearly by millrun and increased by xylanase (P < 0.01) and phytase (P < 0.05). Total tract energy digestibility was reduced linearly by millrun (P < 0.01) and increased by xylanase (P < 0.01). For 20% millrun, xylanase plus phytase improved DE content from 3.53 to 3.69 Mcal/kg of DM, a similar content to that of the wheat control diet (3.72 Mcal/kg of DM). Millrun linearly reduced (P < 0.01) ileal digestibility of Lys, Thr, Met, Ile, and Val. Xylanase improved (P < 0.05) ileal digestibility of Ile. Phytase improved ileal digestibility of Lys, Thr, Ile, and Val (P < 0.05). Millrun linearly reduced (P < 0.05) total tract P and Ca digestibility and retention. Phytase (P < 0.01) and xylanase (P < 0.05) improved total tract P digestibility, and phytase and xylanase tended to improve (P < 0.10) P retention. Phytase improved Ca digestibility (P < 0.05) and retention (P < 0.01). The 9 diets were also fed for 35 d to 8 individually housed pigs (36.2 +/- 3.4 kg of BW) per diet. Millrun reduced (P < 0.05) ADFI, ADG, and final BW. Xylanase increased (P < 0.05) G:F; phytase reduced (P < 0.05) ADFI; and xylanase tended to reduce (P = 0.07) ADFI. In summary, millrun reduced energy, AA, P, and Ca digestibility and growth performance compared with the wheat control diet. Xylanase and phytase improved energy, AA, and P digestibility, indicating that nonstarch polysaccharides and phytate limit nutrient digestibility in wheat byproducts. The improvement by xylanase of energy digestibility coincided with improved G:F but did not translate into improved ADG.

Sites of nutrient digestion in growing pigs: effect of dietary fiber.

The impact of dietary fiber on fecal digestion is well-known and provides a comprehensive approach toward nutrient digestibility and availability. Little quantitative information is available on digestion of fiber in the different segments of the gastrointestinal tract (GIT). The objectives of this study were to obtain a method allowing the quantification of the digestive process in different segments of the GIT and to study the impact of dietary fiber on nutrient digestibility. Six barrows (average initial BW of 30 kg and fitted with a simple T-cannula at the proximal duodenum and caudal ileum) were used in a replicated 3 x 3 Latin square design. In each period, pigs were offered 1 of 3 diets differing in fiber content (low, medium, and high). Differences in fiber content were created by replacing wheat and barley with wheat bran. Titanium dioxide was included in the diet as an indigestible marker to determine the apparent digestibility coefficients in different segments of the GIT. The apparent digestibility of ash, CP, DM, and OM increased in the different segments of the GIT. Duodenal digestibility coefficients were negative for ash (e.g., -39.9% for the medium- and high-fiber diets), indicating important endogenous mineral secretions by the stomach and digestive glands. The duodenal digestibility of other nutrients and OM were positive but close to zero and numerically lower in the diets with the greater fiber contents. The fiber content in the diet did not affect the apparent ileal digestibility of nutrients. Increasing the fiber content in the diet affected the fecal digestibility of CP, ether extract, and energy (P < 0.01). The method used for studying sites of digestion in the digestive tract provides promising results, but it is limited due to the high variability that is likely caused by sampling limitations and variation between animals.

Effects of guar gum and cellulose on digesta passage rate, ileal microbial populations, energy and protein digestibility, and performance of grower pigs.

Dietary guar gum and cellulose were studied as purified soluble and insoluble nonstarch polysaccharide (NSP) sources, respectively. A control diet containing 14% cornstarch was formulated. A 7% guar gum, a 7% cellulose, and a 7% guar gum + 7% cellulose diet were formulated by adding the NSP to the control diet at the expense of cornstarch (wt/wt), forming a 2 x 2 factorial arrangement. The objectives were to determine whether guar gum and cellulose altered 1) the passage rate of digesta through the small intestine and total tract; 2) the digestibility of energy and CP, characteristics of the digesta, and microbial populations in the ileum; 3) plasma glucose and ghrelin concentrations; and 4) short-term voluntary feed intake and growth performance of grower pigs. In Exp. 1, 12 pigs (27.0 +/- 1.5 kg of BW) were fitted with an ileal T-cannula and were used in a 2-period change-over design, providing 6 observations per diet. Each period included 18 d: a 12-d acclimation period followed by 2-d feces, 3-d digesta, and 1-d venous blood collection periods. In Exp. 1, guar gum and cellulose slowed the passage rate of digesta through the small intestine by 26 and 18%, respectively (P < 0.05). Guar gum increased total tract retention time of the digesta by 14% (P < 0.05). Guar gum and cellulose increased the viscosity of ileal digesta by 72 and 76%, respectively (P < 0.05). Cellulose reduced ileal energy and CP digestibility (P < 0.05), but guar gum only tended to decrease ileal energy digestibility (P < 0.10). Guar gum and cellulose reduced total tract energy and CP digestibility (P < 0.05). At 60 min after feeding, guar gum decreased plasma glucose by 10% (P < 0.10). Guar gum interacted with cellulose to reduce plasma ghrelin before and after feeding (P < 0.05). Guar gum and cellulose interacted to increase ileal bifidobacteria and enterobacteria (P < 0.05); however, guar gum, but not cellulose, increased ileal clostridia (P < 0.05). In Exp. 2, 20 individually housed grower pigs (5 pigs per diet) had free access to the 4 diets used in Exp. 1 for 14 d. Guar gum and cellulose decreased ADG and reduced ADFI on d 0 to 14 (P < 0.05). In summary, increasing purified NSP in the diet reduced the passage rate of digesta, energy and protein digestibility, and feed intake, but increased ileal bifidobacteria and enterobacteria populations. The effects of cellulose were similar to those of guar gum. In conclusion, monitoring of dietary NSP is a critical factor to achieve predictable digestible nutrient intake and intestinal bacterial populations.

The efficacy of an Escherichia coli-derived phytase preparation.

Five experiments were conducted to evaluate the effect of an Escherichia coli-derived phytase on phytate-P use and growth performance by young pigs. The first experiment involved time course, pH dependence, and phytase activity studies to investigate the in vitro release of P from corn, soybean meal, and an inorganic P-unsupplemented corn-soybean meal negative control diet. In Exp. 2, which was designed to determine the efficacy of the E. coli-derived vs. fungal phytase-added diets at 0, 250, 500, 750, 1,000, or 1,250 FTU/kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P/min, at pH 5.5, from an excess of 15 microM sodium phytate at 37 approximately C) and a positive control diet, eight individually penned 10-kg pigs per diet (12 diets, 96 pigs) were used in a 28-d growth study. The third experiment was a 10-d nutrient balance study involving six 13-kg pigs per diet (four diets, 24 pigs) in individual metabolism crates. In Exp. 4, eight pens (four pigs per pen) of 19-kg pigs per treatment were used in a 42-d growth performance study to examine the effect of adding the E. coli-derived phytase to corn-soybean diets at 0, 500, or 1,000 FTU/kg (as-fed basis) and a positive control (four diets, 128 pigs). In Exp. 5, six 19-kg pigs per treatment were used in a 10-d nutrient balance study to investigate the effects of the E. coli-derived phytase added to diets at 0, 250, 500, 750, or 1,000 FTU/kg (as-fed basis) and a positive control diet (six diets, 36 pigs). The in vitro study showed that the E. coli-derived phytase has an optimal activity and pH range of 2 to 4.5. Inorganic phosphate release was greatest for soybean meal, least for corn, and intermediate for the negative control diet. Dietary supplementation with graded amounts of E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain, feed efficiency, and plasma Ca and P concentrations in 10-kg pigs in Exp. 2. Phytase also increased P digestibility and retention in the 13-kg pigs in Exp. 3. In Exp. 4, dietary supplementation with E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain and feed efficiency of 19-kg pigs. Supplementation of the diets of 19-kg pigs with the E. coli-derived phytase also improved Ca and P digestibility and retention in Exp. 5. In the current study, the new E. coli-derived phytase was efficacious in hydrolyzing phytate-P, both in vitro and in vivo, in young pigs.

Dietary betaine supplementation affects energy metabolism of pigs.

The effect of dietary betaine supplementation on energy partitioning in growing pigs under energy-restricted dietary conditions was assessed. The effect of betaine on the adaptation in energy metabolism of pigs over time after a change in diet and housing also was studied. Six groups of 14 group-housed barrows were assigned to one of two experimental diets: control or betaine-supplemented (0 or 1.29 g/kg of feed). Diets were corn- and soybean meal-based and were formulated to be limiting in energy content but sufficient in amino acids. The experiment comprised a 3-wk adaptation and a 3-wk experimental period. At the start of the experimental period, initial BW was 46 kg, each group of pigs was housed in a climate-controlled respiration chamber, and all pigs were subjected to a change in diet. During the experimental period, diets were diluted with 10% oat hulls. Pigs were fed at 2.5 times the energy requirements for maintenance, and during the experimental period, heat production, energy, and nitrogen balances were measured weekly. Metabolizibility of energy did not differ (P > 0.10) between diets. Averaged over the experimental period, betaine reduced heat production (P < 0.05) and energy requirements for maintenance (P < 0.10) and consequently increased energy retention (P < 0.10). Moreover, the difference in heat production between diets increased with time (P < 0.05). Similarly, the effect of betaine on the energy requirements for maintenance changed with time (P < 0.05). Maintenance requirements were similar in wk 1 and were decreased by betaine supplementation by 5.5% during wk 3 (477 vs. 452 kJ/[kg(0.75) x d]). Results of this study show that dietary betaine supplementation affects energy partitioning by growing pigs. However, based on the observed time-related changes in energy partitioning, it was concluded that dietary betaine supplementation did not influence adaptation by pigs to a change in housing and diet.

Reducing environmental pollution using animal feed enzymes.

The global livestock population is estimated to be close to 4 billion animals, and to produce around 500 million tons of manure annually (Baidoo, 2003). This is expected to increase in the future with the projected greater demand for meat for human consumption. The problem of manure disposal is exacerbated by the concentration of animal production in increasingly large units, to obtain economies of scale and keep up with the demand for cheap food. The primary environmentalfactors are manure volume, manure nitrogen and phosphorus contents, methane production and odour (Jongbloed and Lenis, 1998). Legislation in many regions now restricts the amount of manure that can be applied per hectare, to prevent environmental pollution (Centner, 2001; Pellini and Morris, 2001). There are a number of strategies the animal production industry can take to reduce environmental impact. These include taking steps to improve the efficiency of conversion of feed into edible products, reduce feed wastage and formulate diets that more closely satisfy animal requirements for specific nutrients. At present 50-80% of the nitrogen and phosphorus fed to animals are not utilized but are excreted via manure and urine to the environment (Baidoo, 2003). Biotechnology could play a very important role in reducing the environmental impact of animal production. Examples include the development of animals more efficient at converting nutrients into edible products, and of higher quality, more digestible feedstuffs. Biotechnology can also be used to produce a range of feed additives that can improve the efficiency of animal production, including for example recombinant somatrophin, amino acids and enzymes. This paper summarizes a series of four experiments looking at the effects of microbial xylanase or phytase supplementation on excretion in swine and poultry. This summary indicates that the inclusion of these enzymes in animal feeds can reduce manure volume by up to 14%, and nitrogen and phosphorus outputs by up to 13% and 70%, respectively.

Timing and causes of piglet mortality in alternative and conventional farrowing systems.

The causes and timing of piglet mortality were studied in different farrowing systems. In the first experiment 198 litters were recorded in three systems, two of which allowed the sows to move freely, and the third restricted them in conventional crates. More piglets were weaned from the conventional crates than from the open systems and they grew more quickly. More than half the liveborn mortality occurred during the first four days after parturition. In the open systems, 17 per cent and 14 per cent of the piglets born alive were crushed, compared with only 8 per cent in the crates. In the second experiment, 29 sows and litters were studied in detail in a communal pen system during the first seven days of lactation. Three-quarters of the liveborn mortality was due to crushing. The total number of piglets dying per litter, including stillbirths, was significantly associated with the total litter size and the sow's parity. The percentage liveborn mortality was significantly associated with the parity and body length of the sows and with the within-litter variation in the birth weight of the piglets. Individual birth weight was closely associated with percentage survival. Only 28 per cent of piglets weighing less than 1.1 kg at birth survived to seven days.

Supplementary biotin for sows: effect on claw integrity.

Eighty female pigs were fed, from 25 kg liveweight, either basal diets calculated to provide 32 micrograms available biotin/kg (control diet) or basal diets supplemented with 350 micrograms biotin/kg. Their claws were examined and lesions recorded at 170 days of age and when each of their first four litters was weaned. The incidence of horn 'defects' (superficial bruises, abrasions and cuts in the soft heel) remained at a low level throughout the trial. Neither the number of claws affected with lesions nor the number of lesions per sow differed between treatments at 170 days of age. Between 170 days of age and first weaning the incidence of hoof lesions increased greatly. At first weaning and for the remainder of the trial biotin supplemented sows had significantly fewer claw lesions per sow than controls (P less than 0.05 or greater). The predominant injuries to the foot were cracks which occurred mainly in two associated regions, the heel/toe junction and the heel, and the sidewall and adjacent white-line region of the toe. The differences in foot damage did not result in differences in culling rate. It was concluded that supplemention of the diet of breeding sows with biotin from an early stage of development made a significant contribution to the maintenance of their horn integrity.

Supplementary biotin for sows: effect on reproductive characteristics.

Eighty female pigs were fed from 25 kg liveweight either basal diets calculated to provide 32 micrograms available biotin/kg (control diet) or basal diets supplemented with 350 micrograms biotin/kg. Reproductive performance was studied over four parities. Sows receiving supplementary biotin returned to oestrus 2.9 +/- 1.7 and conceived 6.1 +/- 1.4 days sooner than controls (P less than 0.05). Of those sows receiving supplementary biotin, more returned to oestrus and conceived within 10 days of weaning (83.2 per cent v 74.6 per cent and 80.6 per cent v 71.8 per cent respectively) and fewer were treated for anoestrus (7.3 per cent v 17.0 per cent) than those on the control diet. Supplementing diets increased the annual productivity of sows completing four parities by 1.42 +/- 1.02 pigs/sow/year (P less than 0.05) and increased the total weight of weaner produced/sow/year by 17.3 +/- 7.4 kg (P less than 0.05). It was concluded that the majority of commercial dietary formulations would require supplementation with biotin in order that sows may express their full reproductive potential.