Performance and phosphorus balance of pigs fed diets formulated on the basis of values for standardized total tract digestibility of phosphorus

Posted in: Environment, Production by admin on July 26, 2011 | No Comments

Three experiments were conducted to test the hypotheses that pigs fed diets that are equal in digestible phosphorus (P) will perform equally regardless of the concentration of total P in the diets, and that the addition of microbial phytase, distillers dried grains with solubles (DDGS), or a combination of phytase and DDGS will result in a reduction in P excretion. In Exp. 1, a P-free diet and 6 diets containing corn, soybean meal (SBM), or DDGS without or with microbial phytase (500 phytase units per kg) were formulated. Diets were fed for 12 d to 42 pigs (initial BW = 13.5kg) housed in metabolism cages that allowed for total collections of feces. Basal endogenous P losses were determined to be 199 mg/kg of DMI for pigs fed the P-free diet. Addition of phytase increased the standardized total tract digestibility (STTD) of P in corn (64.4 vs. 26.4%) and SBM (74.9 vs. 48.3%), but there was no effect of the addition of phytase on the STTD of P in DDGS (75.5 vs. 72.9%). In Exp. 2, a total of 160 pigs (initial BW = 11.25kg; 4 pigs/pen) were allotted to 4 corn- and SBM-based diets with 2 amounts of phytase (0 or 500 phytase units per kg) and 2 amounts of DDGS (0 or 20%) in a 2 × 2 factorial arrangement of treatments. All diets were formulated to contain 0.32% STTD of P according to the STTD values determined in Exp. 1. Diets were fed for 21 d and results indicated that inclusion of phytase in the diet containing no DDGS tended to decrease G:F, but inclusion of 20% DDGS in the diets tended to increase ADG, ADFI, and final BW. In Exp. 3, the diets used in Exp. 2 were fed to 24 pigs (initial BW = 14.6kg) that were placed in metabolism cages individually. Feces and urine were collected for 5 d. Phytase and DDGS increased the apparent total tract digestibility of P in the diets. Absorption of P was greater in pigs fed corn-SBM-DDGS diets than pigs fed corn-SBM diets, and phytase, DDGS, or the combination of phytase and DDGS reduced P excretion. In conclusion, the addition of phytase increased the STTD of P in corn and SBM, but had no effect on the STTD of P in DDGS. Diets may be formulated based on STTD values without compromising pig performance, and dietary phytase, DDGS, or the combination of phytase and DDGS will reduce P excretion by growing pigs. 

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Ileal digestibility of amino acids in conventional, fermented, and enzyme-treated soybean meal and in soy protein isolate, fish meal, and casein fed to weanling pigs

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An experiment was conducted to determine the apparent (AID) and standardized (SID) ileal digestibility of CP and AA in weanling pigs of 4 soybean products, fish meal, and casein. The 4 soybean products were conventional dehulled soybean meal (SBM), soy protein isolate (SPI), fermented soybean meal (FSBM), and enzyme-treated soybean meal (ESBM). Seven weanling barrows (initial BW: 10.9kg) were individually fitted with a T-cannula in the distal ileum. The barrows were allotted to a 7 × 7 Latin square design with 7 diets and seven 7-d periods. Six cornstarch-based diets were prepared using each of the protein sources as the sole source of CP and AA. An Nfree diet was used to measure basal endogenous losses of CP and AA. Results showed that except for Lys, the AID and SID of AA in FSBM was not different from SBM, and with a few exceptions, the AID and SID of most AA in SBM, FSBM, and ESBM were not different from each other and from the AID and SID of AA in fish meal. Likewise, the AID and SID of AA in ESBM and SPI were not different, but the AID and SID of most AA in SPI were greater than in SBM and FSBM. The AID and SID of most AA in SPI were not different from the AID and SID of AA in casein. In conclusion, FSBM and ESBM had similar SID of most AA as SBM, but SPI has the greatest SID of AA among the 4 soybean products. Casein had the greatest SID of AA among the protein sources studied. 

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Energy value of wheat distillers grains with solubles for growing pigs and adult sows

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Two experiments were conducted to determine the total tract digestibility of energy and the DE and ME values of 10 European wheat dried distillers grains with solubles (DDGS) fed to growing pigs and adult sows. The wheat DDGS were obtained from European ethanol plants and selected to get a large variability. One control diet, based on wheat (87.2%), soybean meal (10.0%), and minerals and vitamins, and 10 experimental diets prepared from the control diet and 25% each of the 10 sources of DDGS, were fed to 66 crossbred barrows (6 per diet) according to a factorial arrangement or 6 adult sows according to a pseudo Latin square design. Animals were placed in metabolism cages that allowed for the total, but separate, collection of feces and urine for 8 to 10 d after a 7- to 11-d adaptation period. By subtracting the contribution from the control diet in the DDGS-containing diets (i.e., difference method), N and GE digestibilities and DE and ME values for each source of DDGS were calculated. The energy digestibility in wheat DDGS averaged 66.5% (56.3 to 76.0%) and 71.2% (59.7 to 78.2%) in growing pigs and adult sows, respectively. Consequently, average (range) DE values of DDGS were 14.0 (11.8 to 16.2) and 14.9 (12.5 to 16.4) MJ/kg of DM for growing pigs and adult sows, respectively. Our data show that DE content of wheat DDGS can be predicted from their ADF content or from the lightness score (L). By excluding the dark and overheated samples (L <50) with the least energy digestibility and DE values, the average energy digestibility values were 69.5 and 74.4% in growing pigs and adult sows, respectively, with corresponding DE values of 14.6 and 15.6 MJ/kg DM, which are more representative of a well-controlled process for DDGS preparation. The negative effect of L on energy value and energy digestibility indicates that the occurrence of Maillard reactions should be reduced to maximize the energy value of wheat DDGS for pigs. 

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Effects of feeding diets naturally contaminated with Fusarium mycotoxins on protein metabolism in late gestation and lactation of first-parity sows

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A study was conducted to assess the effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins to sows on the capacity for protein synthesis in skeletal muscle, the protein content per cellular unit, and the efficacy of a polymeric glucomannan adsorbent (GMA) to prevent these effects in late gestation and in lactation. Thirty-two Yorkshire sows were assigned to 4 treatment groups (8 per treatment) from 91d of gestation up to weaning on d 21 after farrowing. Diets included control, contaminated grains, and contaminated grains + 0.2% GMA. A fourth treatment of feeding sows the control diet at a restricted feed allowance was also included. The variables measured include ADFI, average daily BW change, serum total protein, urea, and ammonia, and skeletal muscle DNA, RNA, and protein. To assess the capacity for protein synthesis, ratios of RNA:DNA, and RNA:protein were compared among dietary treatments. To assess the degree of muscle protein mobilization in gestation and lactation, ratios of protein:DNA were compared among dietary treatments. Muscle samples were obtained from the triceps brachii. Blood and muscle samples were obtained 3 times: the first was obtained 1 d before the sows began to receive the experimental diets (90d of gestation), a second sample was obtained 14 d later (104d of gestation), and the third sample was obtained 10 d after farrowing. Serum ammonia concentrations were similar in sows fed the contaminated feed and sows fed the restricted feed compared with controls, but serum ammonia concentrations were greater in sows fed contaminated feed and restricted-fed sows compared with sows fed the contaminated grains plus GMA on 104d of gestation. There were no reductions in the capacity for protein synthesis caused by mycotoxins or restricted feeding compared with controls. A reduction in ADFI was observed in sows fed the 2 contaminated diets in lactation. Muscle protein mobilization was not affected by diet, but a reduction in the content of protein per cellular unit was observed in lactation compared with gestation. Reduction in protein:DNA could be caused by the catabolic state in lactation, which was augmented by a low ADFI. The rate of muscle mobilization could be the result of the indirect effect of the reduction in ADFI in lactation rather than a direct effect of Fusarium mycotoxins in the capacity for protein synthesis. 

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Epistatic analysis of carcass characteristics in pigs reveals genomic interactions between quantitative trait loci attributable to additive and dominance genetic effects

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The present study focused on the identification of epistatic QTL pairs for body composition traits (carcass cut, lean tissue, and fat tissue weights) measured at slaughter weight (140 kg of BW) in a 3-generation full-sib population developed by crossing Pietrain sires with a crossbred dam line. Depending on the trait, phenotypic observations were available for 306 to 315 F2 animals. For the QTL analysis, 386 animals were genotyped for 88 molecular markers covering chromosomes SSC1, SSC2, SSC4, SSC6, SSC7, SSC8, SSC9, SSC10, SSC13, and SSC14. In total, 23 significant epistatic QTL pairs were identified, with the additive × additive genetic interaction being the most prevalent. Epistatic QTL were identified across all chromosomes except for SSC13, and epistatic QTL pairs accounted for between 5.8 and 10.2% of the phenotypic variance. Seven epistatic QTL pairs were between QTL that resided on the same chromosome, and 16 were between QTL that resided on different chromosomes. Sus scrofa chromosome 1, SSC2, SSC4, SSC6, SSC8, and SSC9 harbored the greatest number of epistatic QTL. The epistatic QTL pair with the greatest effect was for the entire loin weight between 2 locations on SSC7, explaining 10.2% of the phenotypic variance. Epistatic associations were identified between regions of the genome that contain the IGF-2 or melanocortin-4 receptor genes, with QTL residing in other genomic locations. Quantitative trait loci in the region of the melanocortin-4 receptor gene and on SSC7 showed significant positive dominance effects for entire belly weight, which were offset by negative dominance × dominance interactions between these QTL. In contrast, the QTL in the region of the IGF-2 gene showed significant negative dominance effects for entire ham weight, which were largely overcompensated for by positive additive × dominance genetic effects with a QTL on SSC9. The study shows that epistasis is of great importance for the genomic regulation of body composition in pigs and contributes substantially to the variation in complex traits. 

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Effect of dietary protein and lysine fluctuations in the absence and presence of ractopamine on performance and carcass quality of late-finishing pigs

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Two experiments with finishing pigs were conducted to evaluate the effects of fluctuating dietary CP levels and ractopamine on performance and carcass traits. In Exp. 1, a total of 408 finishing pigs (mixed sex) were assigned to 1 of 4 protein regimens. Average initial and final BW were 89 and 123 kg, respectively. Pigs on treatments 1 to 4 were fed 16, 11, 16, and 13% CP from wk 0 to 2, respectively. From wk 2 to 5, the pigs on regimens 1 to 4 were then fed 15, 18.33, 18, and 20% CP, respectively, with regimens 3 and 4 also containing supplemental ractopamine (9.9 mg/kg) from wk 2 to 5. Overall (wk 0 to 5), BW gain, G:F, loin depth, percentage of lean, and dressing percentage were improved in pigs on regimens 3 and 4 compared with those on regimens 1 and 2. No statistically significant overall (wk 0 to 5) protein sequence regimen differences occurred between the standard regimens (1 and 3) and the low-high CP regimens (2 and 4). Experiment 2 involved 172 finishing pigs (mixed sex) in 2 protein regimens. Average initial and final BW were 91 and 136 kg, respectively. The diets consisted of a control (16% CP from d 0 to 14, 18% CP + 4.95 mg of ractopamine/kg from d 14 to 24, and 18% CP + 9.9 mg of ractopamine/kg from d 24 to 35); and a low-high CP regimen (12.5% CP from d 0 to 14, 20.33% CP + 4.95 mg of ractopamine/kg from d 14 to 24, and 20.33% CP + 9.9 mg of ractopamine/kg from d 24 to 35). From d 0 to 14, pigs fed the low CP diet (12.5% CP) had reduced BW gain and G:F compared with those fed the control diet (16% CP). In contrast, from d 14 to 35, pigs on the low-high regimen had improved BW gain and G:F compared with pigs on the control regimen. Despite the wide dietary CP fluctuations for pigs in Exp. 2, performance and carcass traits were similar for both regimens over the 35-d test period. These data indicate that pigs fed deficient levels of CP and Lys for 14 d, followed by increased levels of CP and Lys during a subsequent 21-d period can recover and achieve growth performance and carcass merit equal to that achieved with a conventional protein feeding regimen. 

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Dietary supplementation with different forms of flax in late gestation and lactation: Effects on sow and litter performances, endocrinology, and immune response

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The impact of feeding flax as seed, meal, or oil to late-pregnant and lactating sows on hormone concentrations, immune responses, and sow and litter performances was studied. Sixty sows were fed 1 of 4 diets from 68 d of gestation until 21 d of lactation. Diets were standard (CTL; n = 15); 10% flaxseed supplementation (FS; n = 16); 6.5% flaxseed meal supplementation (FSM; n = 14); and 3.5% flaxseed oil supplementation (FSO, n = 15). On d 88 and 101 of gestation, sows were immunized against ovalbumin (OVA). Jugular blood samples were obtained on d 62, 88, and 110 of gestation and on d 2 and 21 of lactation to measure concentrations of estradiol, prolactin, and progesterone as well as antibody (Ab) against OVA (anti-OVA), lymphocyte proliferation, and lymphocyte production of interferon-γ (IFN-γ). Milk samples were obtained on d 3 and 20 of lactation. One piglet per litter was slaughtered on d 1 for compositional analyses, and a jugular blood sample was obtained for anti-OVA analyses. Remaining piglets were weighed on d 2, 7, 14, 21 (weaning), 28, and 56. Circulating hormone concentrations in sows were not affected by treatment overall. On d 20 of lactation, milk from FS, FSM, and FSO sows had more protein than that from CTL sows. The FSM piglets weighed more on d 56 than FS and FSO piglets. Carcasses of 1-d-old FSM piglets also had greater glycogen and DM contents than FS and FSO piglets, but organ weights and circulating concentrations of glucose and IGF-I did not differ. In CTL sows, IFN-γ production decreased between d 101 of gestation and d 2 of lactation, whereas, in FS sows, IFN-γ production increased. Anti-OVA for the whole experimental period was greater in FS than in FSO sows. Concentrations of anti-OVA in milk on d 3 of lactation and lymphocyte proliferative responses were not affected by treatments. Serum concentrations of anti-OVA in 2-d-old piglets that gained BW during the first 24 h after birth were greater in FS, FSM, and FSO litters than in CTL litters and percent mortality on d 2 and 21 postpartum was less for FS, FSM, and FSO litters compared with CTL. Therefore, feeding flax to sows may have beneficial effects on immune resistance of piglets and feeding FSM improved postweaning growth of piglets. 

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Effect of phytase and xylanase supplementation or particle size on nutrient digestibility of diets containing distillers dried grains with solubles cofermented from wheat and corn in ileal-cannulated grower pigs

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Nutrient digestibility in distillers dried grains with solubles (DDGS) is limited by physical constraints such as particle size and by biochemical limitations such as phytate and fiber or nonstarch polysaccharides (NSP). To determine the separate effects of these limitations on nutrient digestibility, ground DDGS (383 μm) supplemented with phytase (0 or 250 units/kg of feed) and xylanase (0 or 4,000 units/kg of feed) was evaluated in a 2 × 2 factorial arrangement of treatments together with unground DDGS (517 μm) and an N-free diet in a 6 × 6 Latin square. Cofermented wheat and corn DDGS contained 8.6% moisture, 31.0% CP, 1.04% Lys, 8.0% ether extract, 2.0% starch, 40% NDF, and 0.85% P (as-is basis). Diets contained 43.7% DDGS as the sole source of AA; the digesta from pigs fed the N-free diet served to subtract basal endogenous AA losses and as control for energy digestibility. Six ileal-cannulated barrows (37.1kg of BW) were fed 6 diets at 2.8 × maintenance for DE in six 9-d periods. Feces and ileal digesta were collected for 2 d each. The apparent ileal digestibility (AID) of GE and apparent total tract digestibility (ATTD) of GE and NDF were 2.3, 0.5, and 5.1%-units greater for the ground than unground DDGS diet, respectively. Consequently, the ATTD of GE was 1.3%-units greater and the DE content was 0.06 Mcal/kg greater for ground than unground DDGS, respectively. Grinding of DDGS did not affect the ATTD of crude fiber, ADF, P, and Ca in diets. Grinding of DDGS increased the AID of most AA in diets including Lys, Met, and Thr by 6.9, 1.1, and 1.7%-units, respectively. Grinding of DDGS increased the SID of Lys by 6.2%-units and SID content of Lys and Thr by 0.06 and 0.02%-units, respectively. Phytase and xylanase did not interact to affect nutrient digestibility. Phytase increased the ATTD of P by 10.5%-units, but did not affect AA digestibility. Xylanase did not affect nutrient digestibility. In conclusion, particle size is an important physical characteristic affecting digestibility of energy and AA, but not P in DDGS. Phytate in DDGS limits digestibility of P, but not energy and AA. The substrate for xylanase in DDGS did not hinder energy and AA digestibility.

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Feed transition between gestation and lactation is exhibited earlier in sows fed a high-fiber diet during gestation

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The underconsumption of feed frequently observed in young sows during lactation can result from an adaptation problem of the sow to the new feeding management in terms of diet composition and feeding amount. Our study aimed to investigate how the sow manages her own feed transition when given the choice between the gestation diet and the lactation diet from moving into the farrowing crate (12 d before farrowing) until the second week postpartum. The effect of adding dietary fiber to the gestation diet on this transition was also evaluated. During gestation, 16 primiparous sows (Large White × Landrace) were fed 2.4 kg/d of a control (CON) diet (3.5% of crude fiber), or 2.9 kg/d of a high-fiber (HF) diet (12.8% of crude fiber). The daily allowance of NE was 24 MJ in both treatments. Twelve days before the expected parturition day (d −12), sows were moved into farrowing crates that were equipped with a computerized feeding device allowing the gestation and lactation diets to be supplied via 2 rewarded push buttons placed above the trough, until d 14 postpartum. The feeding transition was evaluated through the daily ratio of ingestion of the lactation diet. Feeding behavior was measured through daily feed and energy intakes, number of daily meals, meal size, and the nycthemeral distribution of feeding activity. Sows were weighed and backfat thickness was measured at the beginning and end of gestation and lactation. Piglets were weighed every week from birth until weaning. The transition to the lactation diet occurred earlier in HF sows; the 50% threshold of lactation diet ingestion was reached on d −8 and 12 in HF and CON sows, respectively. Dietary treatment did not affect the feeding pattern, and all sows presented a diurnal feeding activity. During lactation, there was an interaction between the hour of the day and the dietary treatment for the distribution of pushes on the rewarded buttons, with pushes being more spread out throughout the day in CON sows compared with HF sows. Variations in sow backfat thickness were not affected by dietary treatment, but HF sows lost more BW during lactation. Growth of piglets was not affected by dietary treatment. In conclusion, sows chose the lactation diet spontaneously on the week preceding parturition when they were fed a fibrous diet during gestation. This highlights the possible impact of such a gestation diet to promote early intake of the lactation diet.

Protein and starch concentrates of air-classified field pea and zero-tannin faba bean for weaned pigs

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Air-classified pulse (non-oilseed legume) protein and starch may replace specialty protein and starch feedstuffs in diets for weaned pigs. In Exp. 1, three specialty protein sources (5% soy protein concentrate, 5% corn gluten meal, and 5% menhaden meal in the control diet) were replaced with 16% zerotannin hulled or dehulled faba bean, or 17.5% field pea protein concentrate. In total, 192 group-housed pigs (2 gilts and 2 barrows per pen; BW = 7.5kg) were fed wheat-based diets (3.60 Mcal/kg of DE and 3.3 g of standardized ileal digestible Lys/Mcal DE) over 28 d for 12 pen observations per each of 4 diets. Overall, protein source did not affect ADFI, ADG, or G:F. Apparent total tract digestibility (ATTD) of DM, GE, and P was greater for dehulled faba bean and field pea protein concentrate diets than the diet with 3 specialty protein sources. In Exp. 2, faba bean and field pea starch concentrates were compared with corn, wheat, tapioca, and potato starch as dietary energy sources. In total, 36 individually housed barrows (BW = 8.0 kg) were fed 1 of 6 diets for 15 d. Feces and urine were collected from d 8 to 14, and jugular blood was sampled after overnight fast and refeeding on d 15. Starch source did not affect N retention as a percentage of N intake. For d 0 to 14, ADFI of pigs fed field pea starch was greater than pigs fed corn, wheat, potato, and faba bean starch. Pigs fed tapioca, field pea, wheat, or corn starch grew faster than those fed faba bean or potato starch. For d 0 to 14, pigs fed corn or wheat starch had a 0.1 greater G:F than pigs fed faba bean, field pea, or potato starch. The ATTD of DM, GE, CP, and starch and the DE value of potato starch were much less than those of other starch diets. Postprandial plasma glucose was 4.9, 6.3, and 9 mmol/L greater for pigs fed tapioca than for pigs fed faba bean, wheat, and potato starch, respectively. However, postprandial plasma insulin tended to be 844 and 577 pmol/L greater for pigs fed faba bean and corn starch, respectively, than for pigs fed potato starch. The high insulin response of pigs fed faba starch could not be explained. In conclusion, air-classified pulse protein concentrates can replace specialty protein feedstuffs in diets for weaned pigs. Feeding air-classified pulse starch concentrates to starter pigs achieved a similar N retention as a percentage of N intake. The factors responsible for the reduced ADFI associated with feeding faba bean starch remain unclear. 

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