The Nutritional Strategies On Depressing Boar Taint And Aggressive Behaviors Of Male Pigs

Castration has been widely used in the pork production of male pigs for the main purpose to control the boar taint,to reduce the aggressive behavior,and to increase the proportion of fat in carcasses moderately.However,Entire male pigs have higher feed conversion ratio,higher carcass lean ratio,and higher polyunsaturated fatty acids level in the muscles and adipose tissues than castrates(Barrow),and with the increased concern for animal welfare the advantages of castration are disputable.Thus,there is an urgent need to conduct in-depth research to reduce the boar taint and unwanted behaviors to provide a theoretical reference for the production of male pigs,and to improve the male pigs’welfare.In current study,consumers’ acceptance of pork with different levels of boar taint was surveyed;How host gender affects the bacterial community in pig feces and its correlation to skatole production was investigated;The effects of raw potato starch on microbial community in feces,and skatole levels in feces and backfat of male pigs were evaluated in this study;Interrelationships among sex behavior,androstenone,skatole levels and sexual maturity was also investigated;Finally,we determine the effects of housing system,slaughter weight and supplemental tryptophan on sexual maturity,boar taint levels and aggressive behavior of entire male pigs.1 Survey on Chinese consumers acceptability of entire male porkThe aim of this work was to study consumers’ acceptance of pork with different levels of boar taint according to their androstenone and skatole sensitivity in China.The 120 consumers involved in experiment were classified as sensitive to the odor of pure androstenone and skatole or sensitive perceiving them as like or dislike,then consumers scored the odor and the flavor of the samples.Pork samples were classified as ’barrows’,’LL group’(low levels of androstenone and skatole)and ’LH group’(high levels of androstenone or skatole).60.9%of consumers were high sensitive to skatole and 18.2%of consumers were high sensitive to androstenone.As sensitivity to androstenone increased,consumers acceptance of pure androstenone odor significantly reduced(χ2 = 22.41,P<0.001).47.8%of consumers like/neural pure skatole odor,25.0%of consumers dislike pure androstenone odor.Consumers’ acceptability of the odor(χ2=3.75,P<0.05)and taste of LH group meat was higher than LL groups.Consumers who high sensitive to androstenone and like/neural it odor scored the flavor of the meat from LL and LH groups higher than barrow.However,There were no significant differences in consumer’s evaluation of meat from barrow,LL group,and LH group.2 How host gender affects the bacterial community in pig feces and its correlation to skatole productionTo clarify the role of intestinal microbiota on skatole production and the influences of host gender on,individual fecal samples were collected from female,castrated and entire male pigs at the ages of 20,85,and 185 days.Concentrations of skatole in feces were determined by high performance liquid chromatography(HPLC),and the bacterial community in the pig feces was analyzed using 454-pyrosequencing based on 16S rRNA genes.Results showed that,compared to the gilts,the phyla Firmicutes was lower in boars and barrows,and the abundance of Proteobacteria was higher in barrows.The host gender significantly affected the proportion of 10 and 11 genera in total community at the ages of 85 and 185 days,respectively.Skatole concentrations in entire male pigs were higher than in gilts at 20 days.No significant differences in the feces of different-gendered pigs remained at 85 and 185 days.The fecal skatole concentrations significantly related to the presence of some genera of Bacteroidetes and Firmicutes in the feces,including Clostridium and Oscillibacter.This is the first study using a barcoded DNA pyrosequencing method to survey pigs’ fecal microbiota composition by gender.This gender-related microbiota correlated with the fecal concentration of indolic compounds.These results provide a new vision for pig welfare,as well as the possibility of controlling boar taints by modulating the gut microbiota instead of castration.3 Effect of raw potato starch addition and castration on fecal microbiota and skatole levels in backfat and feces of entire male pigs16 entire and 16 castrated male pigs with an average BW of 60 kg were respectively assigned to two diet treatments,which were basal diet and basal diet with 5%RPS supplementation.The fecal microbiota was analyzed by Real-time PCR and high-throughput 16S rDNA gene sequencing.Skatole levels in feces and backfat were determined by HPLC.Results showed that,dietary RSP significantly reduced skatole levels in both feces and fat of pigs(P<0.05).Both sequencing-based and quantitative PCR-based microbial composition in pigs’ feces revealed no significant differences at the phylum level caused by dietary RPS(P>0.05).However,the remarkable differences due to dietary RPS were observed at the genus level.Sequencing-based composition revealed that dietary RPS decreased the relative abundance of Streptococcus,Eubacterium,Treponema,unclassified Erysipelotrichaceae,unclassified Bacteroidales and unclassified Sphingobacteriales(P<0.05),but increased the relative abundance of Butyricicoccus(P<0.05).Real-time PCR analysis revealed that dietary RPS increased the counts of Lactobacillus,Clostridium IV and XIVa(P<0.05),decreased the E.coli counts(P<0.05).These results indicated that dietary RPS significantly reduced skatole levels in both feces and backfats of entire and castrated male pigs;this might be a result of altering the composition of the intestinal microflora.4 Effect of housing system and slaughter weight on sexual maturity and boar taint levels in entire male pigs80 entire male piglets were reared following either a farrow to finish strategy in which no mixing was allowed(FTF,40 pigs)or following a conventional strategy in which piglets were randomly mixed when entered to the nursing and fattening pens at 32 and 68 days of age(MIX,40 pigs).Sex behavior was observed at 32 and 68 days immediately after mixing.Blood was collected after behavior observation.At a live weight of 90 and 105 kg,pigs were killed to obtain backfat for androstenone and skatole measuring.The results show that At growth phase,the ADG was higher in FTF group when compared with MIX group(P<0.05).Behavioral observations showed entire pigs in FTF group were less sexual behaviors than MC-groups(P<0.05).Plasma testosterone concentrations were decreased significantly in FTF-groups(P<0.05).The levels of androstenone and skatole,backfat thickness and loin depth,as well as lean meat content,were not affected by rearing system and slaughter weight(P>0.05).However,the percentage of pig with high levels of androstenone and skatole in low slaughter weight and FTF groups were lower than the high slaughter weight group and MIX groups.5 Effect of supplemental L-tryptophan and housing system on aggressive behavior of entire male pigsThe aim of this study was to investigate the effect of supplemental L-tryptophan and housing system on aggressive behavior and physiological indicators of male pigs’ welfare.120 male piglets were reared following either a farrow to finish strategy in which no mixing was allowed(FTF-group,40 pigs)or following a conventional strategy in which piglets were randomly mixed when entered to the nursing and fattening pens(MIX-group,80 pigs).After the MIX piglets were moved to the nursing pens,they were assigned randomly to two groups(40 piglets per group).The Control group was fed the basal diet(MC-group),the treatment groups with basal diets plus an additional 0.5%tryptophan(MT-group).Behavior was observed immediately after mixing.Blood was collected after behavior observation.Number of skin lesions and carcass quality were assessed for each animal.On d 170,pigs were killed to obtain hypothalamic and backfat.After mixing and relocation,entire pigs in FTF-group were less aggression than MC-groups(P<0.05).More skin lesions were recorded in the MC-group compared to FTF-group pigs(P<0.05).Plasma norepinephrine and epinephrine concentrations were decreased significantly in FTF-groups(P<0.05).Supplementation of L-tryptophan increased hypothalamic 5-HT.No effect of L-tryptophan Supplementation on plasma norepinephrine and epinephrine concentrations(P>0.05).No significant difference in aggressive behavior was found between MC-group and MT-group(P>0.05).The percentage of pigs with more than five skin lesions decreased significantly in supplemental dietary tryptophan groups(P<0.05).The results indicate that rearing entire males in sibling groups may be an appropriate management strategy for improving animal welfare in entire male pig production.