Studies On The Interaction Between Genetic Background And Nutrition In China Red Cattle And Its Crossed Herds

A series of experiments were conducted to study the influences of genetic background and nutrition on feed efficiency, performance, blood index, gene expression as well as the interaction effect of genetic background and nutrition. Forty heads of china red cattle and its crossed herds were introduced, and multi-factor design was employed. Results of the study identified the basic regulation of nutritional metabolism in animals. Genetic markers could be used for marker assisted selection (MAS) and blood index related to beef traits and feed efficiency were found. Mechanisms of molecular biology for the differences of nutrient metabolism were discussed. Models of interaction between genetics and nutrition were established. Basic regulars of interaction between genetics and nutrition, genotype and nutrition, as well as the interaction effect on certain traits were revealed primarily. Concept of comparative animal nutrition (CAN) was deepened and flourished. Gaps of relevant studies in red cattle were filled.From the results of this study, performance and feed efficiency were influenced by genetic and nutritional factors at the same time. Daily gain (DG) and feed efficiency decreased with the increase of nutritional level of diets in red cattle while crossed herds were on the contrary. Energy retention and the efficiency in red cattle were higher than that in crossed herds under higher nutrition level (P＜0.01), while it was on the contrary under lower nutrition level (P＜0.05). Energy retention in red cattle under higher level of nutrition was higher than that of lower nutrition (P＜0.01). Protein retention in crossed herds was higher than red cattle (P＜0.05), and increased with nutrition level. Higher nutrition level contributed to eye muscle area, marbling score and lower shear force.Blood index varied among genetic and nutritional treatments. Urine nitrogen in crossed herds were higher than red cattle under two nutrition groups (P＜0.05). It was higher in higher level groups than that of lower level groups within genetic herds. Interaction existed between genetics and nutrition on nitrogen transfer enzyme (P＜0.01). There were differences of IGF-I among genetic herds (P＜0.01). It was higher in crossed herds than that of red cattle. There were significant differences among groups of nutrition (P＜0.05) and it increased with nutrition level. Correlation existed among GH, IGF-Ⅰ, and enzyme to slaughter traits and beef quality traits. There were correlations among GPT, GOT, LDH, AKP, Amy and IGF-Ⅰto marbling, eye muscle area and ratio of meat and bone in different degrees.Genetic variance and beef quality performance in red cattle and crossed herds were analyzed with microsatellite makers. All the 8 microsatellite loci were highly polymorphic in two herds and IDVGA44 was the best selection marker. Correlation analysis indicated that C allele of BM2113 locus has positive effect on lean meat weight and lean meat percentage. C allele of IDVGA46 locus has negative effect on carcass weight, slaughter rate, lean meat weight and lean meat percentage. E allele of TGLA44 locus has positive effect on some slaughter traits such as body weight, carcass weight and lean meat weight. Results of sequence analysis on SNP site of MSTN exon-1 showed that a single nucleotide transition (C/A) occurred at site 282 in crossed herds which caused a change of amino acid change from Phe to Leu and there was no mutation in red cattle. The effect of genotype for MSTN gene was analyzed with least-square method and the result showed that all the 9 beef traits but kidney fat was significantly related to genotypes of SNP site in crossed herds. The effect of different genotype analysis indicated that B allele has positive relation with daily gain significantly, and has no relation with other traits.There was a G/A transition at site 142 of H-FABP gene's 5' flanking region identified by sequence analysis. Variance analysis indicated that nutrition level, genetic background and H-FABP gene had influences on traits of digestive metabolism, slaughter and beef quality, of which nutrition played dominant effect on digestive metabolism and genetic background mainly on slaughter traits. But it was much more complex for beef quality traits, muscle fiber diameter was mainly influenced by genetic background, marbling score by nutrition level, and shear force mainly by H-FABP gene as well. Under higher nutrition level, the nutrient elements had a greater effect on performances, but the genotype effect would be more dominant for decision of digestive metabolism and beef quality. Different genotypes had greater effect on shear force under higher nutrition level, and on marbling and muscle fiber diameter under lower nutrition level, but little effects on slaughter traits.There were differences for IGF-Ⅰexpression volume The results of analysis for IGF-Ⅰexpression volume under different nutrition level showed that IGF-Ⅰexpression volume was significantly different in red cattle and was different but not significantly in crossed herds. It was lower for IGF-Ⅰexpression volume in red cattle than in crossed herds under low nutrition level and was significantly higher under high nutrition level. Expression volume of IGF-Ⅰin liver increased with nutrition level in both herds. IGF-Ⅰexpression had great effect on blood index under different nutrition level. Under low nutrition level, IGF-Ⅰexpression volume had low-negative correlation in red cattle and high-negative in crossed herds to urine nitrogen, and low-negative in red cattle and medium-positive in crossed herds with blood sugar, and also negative correlation in red cattle and positive correlation in crossed herds with A/G, G, ChE, AKP and IGF-Ⅰconcentration. Under high nutrition level, IGF-Ⅰexpression volume had negative correlation (-0.32) in red cattle and positive correlation in crossed herds with GH (0.39), and related coefficient with ChE and Amy concentration decreased from 0.45 and 0.82 in red cattle to 0.17 and 0.31 in crossed herds, respectively.IGF-Ⅰexpression has a great effect on traits within the same genetic groups under different nutrition level. In red cattle, its expression volume had high-positive correlation with crude protein and energy deposition under low nutrition level and medium-negative correlation under high nutrition level. For beef quality traits, its correlations were positive with marbling, beef color, dehydration ratio, water loss under low nutrition level and with muscle fiber diameter, marbling under high nutrition level. Its expression volume had low-positive correlation with loin muscle area, daily gain and little correlation with other slaughter traits. In crossed herds, IGF-Ⅰexpression volume had positive correlation under low nutrition level and negative correlation under high nutrition level with all digestive and metabolic traits. Its related coefficient with daily gain and loin muscle area under high nutrition level much more increased than that under low nutrition level. For beef quality traits, its correlations with marbling and dehydration ratio were medium-positive under low nutrition level and negative under high nutrition level, but its related coefficient with shear force was greatly increased under high nutrition level.IGF-Ⅰexpression had also great effect on traits in different population under the same nutrition level. Under low nutrition level, its expression volume had high-positive correlation with crude protein and energy deposition in red cattle, but in crossed herds, its correlations with both traits were lower and much higher with other digestive and metabolic traits as dry material, crude fiber and energy. Its correlation with loin muscle area was reversed in red cattle and crossed herds. For beef quality traits, its correlations were positive with marbling, meat color, dehydration ratio, water loss in red cattle and positive with marbling, dehydration ratio, but negative with water loss, meat color in crossed herds. Under high nutrition level, all the correlations were negative with digestive and metabolic traits in both population except with crude fat which was positive in red cattle, and the coefficient was higher in crossed herds than that in red cattle. Its related coefficients with loin muscle area and daily gain were much higher in crossed herds than that in red cattle. Under high nutrition level, its correlations with most beef traits were reversed in red cattle and crossed herds, such as pH (-0.46: 0.29), marbling (0.29: -0.22), shear force(-0.14: 0.57), water loss (0.13: -0.41), and so on, which showed that genetic background played important role on beef quality under high nutrition level.There were interaction effects of nutrition and H-FABP genotype or nutrition and genetic backgrounds on digestive metabolism, slaughter and meat traits. Interaction between nutrition and genetic backgrounds was significant on digestive and metabolic traits like dry material, crude protein, energy, and interactions between genotype and nutrition on crude fat and dry material was also significant. The marbling and shear force were greatly influenced by the interaction between nutrition and H-FAPB genotype, and the interaction effect on dehydration ratio was greatly influenced by nutrition and genetic backgrounds. There were no significant interactions on slaughter traits. Both kinds of interactions had similar interaction effects on IGF-Ⅰexpression and concentration in serum but had not significant difference.