Effects Of Vitamin A Supplementation During Young Period On Production Performance,Carcass Quality And Meat Quality In Post-weaning Tan Lambs

Intramuscular fat is a crucial factor in determining the flavor,juiciness,and tenderness of meat,and serves as a key indicator for assessing the quality of meat products.The period from birth to post-weaning is a critical window period for the formation of intramuscular fat in animals,during which precise nutritional regulation can significantly enhance intramuscular fat deposition and improve meat quality.Previous research has demonstrated that supplementing with vitamin A during lactation could effectively increase body weight and gene expression levels related to intramuscular fat deposition in Tan sheep at weaning,while its impact on post-weaning still remains unclear.Therefore,this study aimed to investigate the effects of vitamin A supplementation during the critical window period of intramuscular fat formation on the production performance,carcass quality,and meat quality of post-weaning Tan sheep.The findings of this study will provide a scientific basis for the further application of vitamin A in Tan sheep production.A total of 45 healthy lambs,born around the same time and with similar weights(4.38±0.23 kg),were randomly divided into three groups.Each group had three replicates(pen),with five lambs in each replicate.The ewes and lambs were kept in the same pen.The control group(CON)was given regular milk,while the experimental groups were given regular milk along with oral administration of 30,000 IU of vitamin A(L group)or 60,000 IU of vitamin A(H group)at one day and one month of age,respectively.All lambs were weaned at 70 days and fed fed basic feed for 120 days.Then,the carcass and meat quality were measured.The findings suggest that:1.The inclusion of vitamin A in the diet of Tan sheep during lactation has been found to have a significant impact on their production performance.In comparison to the control group,the body weight of Tan sheep in the low and high vitamin A groups increased by 1.51 and 1.37 kg respectively,on 30th days(P<0.05),respectively.Furthermore,on the 60th day,the body weight significantly increased by 1.61 and 1.76 kg(P<0.05),respectively.However,there was no significant difference in body weight between the low and high vitamin A groups(P>0.05).In addition,there were no significant differences in body weight on the 90th and 120th day,average daily gain,average daily feed intake,feed gain ratio,and body size indicators among the three treatment groups(P>0.05).It is noteworthy that the effect of vitamin A supplementation during lactation on production performance gradually decreases over time.2.Supplementation of vitamin A during lactation has been found to enhance the serum biochemical indicators and body antioxidant capacity of Tan sheep during fattening period.In comparison to the control group,the serum urea nitrogen(SUN)levels in the L and H groups decreased by 1.29 and 0.76 mmol/L(0.05 ≤ P<0.10),respectively,while the glucose(GLU)levels increased by 0.87 and 1.46 mmol/L(0.05 ≤ P<0.10),respectively.Additionally,the total superoxide dismutase(T-SOD)levels in the serum increased by 11.95 and 18.5 U/mL(0.05 ≤ P<0.10),respectively.The catalase(CAT)levels in the longissimus dorsi muscle of the L group significantly increased by 1.75 U/mg(P<0.05).The serum biochemical indicators and antioxidant capacity of the L and H groups of Tan sheep were improved,with the L group exhibiting the strongest antioxidant capacity.3.Supplementation of vitamin A during lactation has been found to enhance the meat quality during fattening period.In comparison to the control group,Tan sheep in the L and H groups exhibited an increase in muscle moisture content by 2.16%and 1.76%,respectively,while intramuscular fat content increased by 1.28%and 0.84%(P<0.05),respectively.Moreover,the marbling score increased by 1.05 and 0.62(P<0.05),and the expression levels of genes related to intramuscular fat deposition,namely ZFP423,WNT10B,FABP4,and ACACA,were significantly augmented(P<0.05).Furthermore,the shear force of the longissimus dorsi muscle in the L and H groups of Tan sheep decreased by 3.76 and 2.51 N,respectively(P<0.05),and the meat color a*value increased by 1.22 and 0.56(P<0.05)at 45 minutes post-slaughter.The pH value at 24 hours after slaughter also increased by 0.21 and 0.12(P<0.05),respectively.When compared to the H group,the L group exhibited higher intramuscular fat(0.44%),marbling score(0.4 1),45 minute post-slaughter meat color a*value(0.66),and 24 hour post-slaughter pH value(0.09),as well as lower shear force(1.09 N).Overall,the meat quality of both L and H groups of Tan sheep was significantly improved,with the L group exhibiting the best meat quality.In brief,the provision of vitamin A at the critical window period of intramuscular fat formation can have a substantial positive impact on the production performance of Tan sheep.Specifically,it can lead to an improvement in the body’s antioxidant stress,intramuscular fat content,marbling score,and gene expression levels that are associated with intramuscular fat deposition during the period of fattening,thus enhancing meat quality.Under the conditions of this experiment,the suggested vitamin A supplement dosage for Tan sheep during lactation is 30,000 IU.