Response to an Escherichia coli K88 oral challenge and productivity of weanling pigs receiving a dietary nucleotides supplement

Background： Dietary nucleotides, considered as antibiotics alternative, were shown to have positive effects on intestinal hyperaemia, systemic immunity, small-intestinal growth, and hepatic composition in pigs. However, there is no previous research on nucleotide supplementation in weanling pigs under an oral challenged E. coil K88. Therefore, 2 experiments were conducted to investigate the effects of dietary nucleotides on weanling pig growth performance, nutrient digestibility, fecal score, and blood profile after being orally challenged with E. coli K88. Methods： In Exp. 1, a total of 140 weanling pigs [8.33 ± 0.33 kg of body weight （BW）, 28-d old] were used in this 42-d feeding trial. Pigs were distributed into 1 of 4 treatments, 5 pigs/pen （3 barrows and 2 gilts） and 7 pens/treatment. Treatments were a control basal diet （CON） or the CON supplemented with 150 （R150）, 220 （R220）, or 275 （R275） mg/kg to give the three treatment diets. In Exp. 2, 28 weanling pigs （BW = 8.40 ± 0.22 kg, 28-d old） were distributed into 1 of 4 treatments to give 1 pig/pen and 7 pens/treatment in a 42-d feeding and challenge trial. Dietary treatments were the same as in Exp. 1. 0n d 14, all those pigs （BW= 13.3±0.15 kg, 42-d old） were orally dosed with 1.5 mL suspension containing 10 cfu/mL of E. coli K88. Twenty four hours after challenge, blood and excreta samples were collected from each pigs for analysis. Fecal scores were measured on d 7, 14, 21, and 28 of the study. Results： In Exp. 1, overall BW, average daily gain （ADG）, gain/feed （G/F） ratio, and nutrient digestibilities were lower （P 〈 0.05） in CON group compared with the nucleotides fed pigs. In Exp. 2, after challenge, IgA, IgM, and IGF-I were higher （P〈 0.05） in the nucleotide groups compared with CON. However, the nucleotide groups had lower （P 〈 0.05） cortisol and TNF-o compared with CON. Fecal E. coil counts and fecal score for the nucleotide groups were lower （P 〈 0.05） than for CON. Conclusions： In conclusion, dietary nucleotides supplementation could improve growth performance, nutrient digestibility, immune status, microbial balance, reduce diarrhea, and provide protection against enterotoxigenic E. coli K88 infection in weanling pigs.

Glutamic acid supplementation recovers the reduced performance of weanling pigs fed reduced crude protein diets

This study was conducted to evaluate the supplementation of glutamic acid(Glu)to reduced protein diets on the performance of weanling pigs.One hundred and eighty crossbred weanling pigs([YorkshireLandrace]Duroc,21 d old)having similar body weight(BW)of 6.45 kg were randomly allotted to 1 of 6 dietary treatments(5 pigs per pen[2 barrows and 3 gilts];6 pens per treatment)based on BW and sex during a 6-week trial.Dietary treatments consisted of positive control(PC)diet formulated to have 226.9,205.6,and 188.8 g crude protein(CP)during phases 1,2,and 3,respectively,and negative control(NC)diets with 20 g CP reduction from PC diets and addition of Glu with increasing levels,resulting in the calculated Lys-to-Glu ratios of 1:2.25,1:2.30.1:2.35,1:2.40,and 1:2.45,designated as NC,NC1,NC2,NC3,and NC4,respectively.The BW of pigs receiving PC diet was higher(P<0.05)than those receiving NC diet at d 7,21 and 42.A higher(P<0.05)average daily gain(ADG)from d 1 to 7,8 to 21,22 to 42 and during the overall experiment period was observed in pigs fed PC than NC diet.Pigs fed NC diets including the graded level of Glu linearly increased(P<0.05)BW at d 42,ADG and gain-to-feed ratio(G:F)during the overall experimental period.In addition,trends in linear increase in BW(P=0.056)at d 7 and ADG from d 1 to 7 and d 22 to 42(linear effect,P=0.081,P=0.058 respectively)were observed.A tendency in the linear increment of NH3(P=0.082)at d 21 and linear reduction in methyl mercaptans(P=0.054)emission at d 42 was observed in pigs fed NC diets supplemented with graded level of Glu.In conclusion,supplementing the reduced protein diet with Glu enhanced the growth performance in weanling pigs suggesting that supplementation of Glu can compensate the reduction of 2%CP in the basal diets.

The role of lactose in weanling pig nutrition:a literature and meta-analysis review

Lactose plays a crucial role in the growth performance of pigs at weaning because it is a palatable and easily digestible energy source that eases the transition from milk to solid feed.However,the digestibility of lactose declines after weaning due to a reduction in endogenous lactase activity in piglets.As a result,some lactose may be fermented in the gastrointestinal tract of pigs.Fermentation of lactose by intestinal microbiota yields lactic acid and volatile fatty acids,which may positively regulate the intestinal environment and microbiome,resulting in improved gastrointestinal health of weanling pigs.We hypothesize that the prebiotic effect of lactose may play a larger role in weanling pig nutrition as the global feed industry strives to reduce antibiotic usage and pharmacological levels of zinc oxide and supra-nutritional levels of copper.Evidence presented in this review indicates that high dietary lactose improves growth performance of piglets,as well as the growth of beneficial bacteria,particularly Lactobacillus,with the positive effects being more pronounced in the first 2 weeks after weaning.However,the risk of post-weaning diarrhea may increase as pigs get older due to reduced lactase activity,high dietary lactose concentrations,and larger feed intakes,all of which may lead to excessive lactose fermentation in the intestine of the pig.Therefore,dietary lactose levels exert different effects on growth performance and gastrointestinal physiological functions in different feeding phases of weanling pigs.However,no formal recommendation of lactose for weanling pigs has been reported.A meta-analysis approach was used to determine that diets fed to swine should include 20%,15%,and 0 lactose from d 0-7,d 7-14,and d 14-35 post-weaning,respectively.However,sustainable swine production demands that economics must also be taken into account as lactose and lactose containing ingredients are expensive.Therefore,alternatives to lactose,so called“lactose equivalents”have also been studied in an effort to decrease feed cost while maintaining piglet performance with lower dietary lactose inclusions.In summary,the present review investigated dose-response effects of dietary lactose supplementation to exert positive responses and begin to elucidate its mechanisms of action in postweaning pig diets.The results may help to replace some or all lactose in the diet of weanling pigs,while improving production economics given the high cost of lactose and availability in some swine production markets.