| A randomized block design was employed in this study, in order to study the effect of dietary forage to concentrate ratio on production performance, slaughtering performance, meat quality and transcriptional expression of genes on fat deposition of Dazu black goat.There were 32 three-to-five-months-old Dazu black goats were divided into eight groups. Each group had four goats with similar initial body weight and date of birth. The four goats in each group were randomly assigned to feeding one of four dietary (8 goats/dietary). Four diets of the forage to concentrate ratio were 4:6 (A1),3:7 (A2),2:8 (A3) and 1:9 (A4), respectively. The feeding trial lasted for 59 days. Indices including production performance, slaughtering performance, blood lipid metabolism and meat quality were measured. And then the transcriptional level of FAS and H-FABP genes were analyzed by Real-time PCR. The results are as fellows:1. Final body weight and average daily gain (ADG) were increased, and then feed conversion ratio (FCR) was decreased with the increase of dietary forage to concentrate ratio. Final body weight of group A1 were the greatest among four groups (P<0.01), but there was no significance between group A3 and A4 (P>0.05). ADG of group A1 to A4 were 126.27 g/d±10.73 g/d、112.29 g/d±11.98 g/d,81.14 g/d±9.43 g/d,73.30 g/d ±9.14 g/d, respectively. ADG of group A1 and A2 were greater than group A3 and A4 (P <0.01), and there was significant difference between group A3 and A4 on ADG (0.01< P<0.05). FCR of group A1 to A4 were 7.01 g/g±0.85 g/g,7.91 g/g±1.13 g/g、9.64 g/g ±1.14 g/g,10.69 g/g±1.13 g/g, respectively, and there was significant difference among four groups (P<0.01).2. With regard to slaughtering performance, slaughter weight of group A1 and A2 were higher than those of group A3 and A4 (P<0.01), but there was no significance between group A1 and A2 (P>0.05). Carcass weight of group A1 was the greatest among group A2, A3 and A4 (P<0.01), and there was significant difference between group A3 and A4 (0.01<P<0.05). Dressing percentage of group A1 to A4 were 39.17% ±0.50%,36.62%±0.78%,34.81%±0.25%,33.97%±0.56%, respectively, and group A1 was the greatest among four groups (P<0.01), but there was no significant difference between group A3 and A4 (P>0.05). Lion muscle area of group A1, A2 and A3 was higher than that of group A4 (0.01<P<0.05), but there was no significance among of the group A1, A2 and A3 (P>0.05).3. With regard to meat quality, (1) pH24h, drip loss and meat color were not affected by the forage to concentrate ratio (P>0.05). Compared with group A1, cooking loss of group A2, A3 and A4 were increased significantly (P<0.01), but there was no significant difference between group A3 and A4 on cooking loss (P>0.05). Shear force (SF) of group A1 and A2 were lower than those of group A3 and A4 (P<0.01), but there was no significance between group A1 and A2 (P>0.05). Dehydration rate of group A1 to A4 were 13.04%±0.34%、13.50%±0.23%,13.94%±0.14%、14.44%±0.13%, respectively, and there was significant difference among four groups (P<0.01). Water-holding capacity (WHC) of group A1 was higher than group A2, A3 and A4, but there was no significant difference between group A2 and A3, group A3 and A4on WHC (P>0.05). (2) There was no significant difference among four groups on moisture (P> 0.05). Compared with group A1, crude protein of group A2 was decreased (0.01<P< 0.05), and that of group A3 and A4 were decreased significantly (P<0.01), but there was no significant difference between group A2 and A3, group A3 and A4(P>0.05). Crude fat of group A1 to A4 were 1.57%±0.09%、 1.30%±0.10%、1.12%±0.04%、1.08%± 0.04%, and group A1 was higher than that of other group (P<0.01), but there was no significance between A3 and A4 (P>0.05). With regard to amino acid, seventeen free amino acids and total amino acid (TAA) of group A2 was higher than that of other group, and the sequence of descend order was group A2, group A3, group A4, group A1. There was significance among four groups to aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), lysine (Lys) and alanine (Ala) (0.01<P<0.05). The content of flavor amino acid in each group was A1 7.25 g/100g±0.39 g/100g、A28.10 g/100g±0.71 g/100g、A37.84 g/100g±0.51 g/100g. A47.34 g/100g±0.31 g/100g. Fatty acid in longissimus dorsi muscle, saturated fatty acid (SFA) was decreased with the decrease of the forage to concentrate ratio, but the SFA was increased when the forage to concentrate ratio was 1:9. On the contrary, unsaturated fatty acid (UFA) was decreased with the increase of the forage to concentrate ratio, and the indices was decreased in group A4. There was significant difference among four groups to palmitic acid (C16:0), oleic acid (C18:1), a-linoleic acid (C18:3), arachidic acid (C20:0), eicosenoic acid (C20:1) and lignoceric acid (C24:0) (0.01<P<0.05). UFA of group A1,A2, A3, A4 were 46.75%±0.88%、 52.27%±1.33%、57.08%±2.20%、51.26%±1.47%, respectivly. The results showed that content of UFA was increased and content of SFA and flavor amino acid were decreased with the increase of forage level within certain limits, but low forage to concentrate ratio decreased the content of UFA in mutton.4. With the decrease of the forage to concentrate ratio, triglyceride (TG), total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) were decreased, and these indices reached the minimum value on the group A4. TG of group A1 to A4 were 3.31 mmol/L+0.27 mmol/L、2.37mmol/L±0.37mmol/L、2.08 mmol/L±0.44 mmol/L、1.83mmol/L± 0.33 mmol/L, and TG of group A1 was higher than those of group A2, A3 and A4 (P< 0.01), but there was no significance among group A2, A3 and A4 (P>0.05). There was significant difference among four groups to TC and HDL-C (P<0.01). Compared with group A3 and A4, LDL-C of group A1 and A2 increased significantly (P<0.01), but there was no significance between group A3 and A4 in LDL-C (P>0.05). With regard to serum volatile fatty acid (VFA), acetic acid/propanoic acid was decreased with the increase of forage to concentrate ratio, and group A1 was 0.82±0.04, A2 was 0.92± 0.05, A3 was 1.80±0.25, A4 was 2.07±0.48, and group A1 was lower significantly than group A3 and A4 (P<0.01), and group A2 was lower significantly than group A3 and A4 (0.01<P<0.05), but there was no significance between group A1 and A2 on acetic acid/propanoic acid (P>0.05). Acetic acid, propanoic acid and butyric acid of serum firstly were increased and then decreased, and group A2 reached the maximum (P< 0.01).5. Transcription level of FAS and H-FABP genes in liver tissue was decreased with the decrease of forage to concentrate ratio. Expression level of FAS and H-FABP genes of group A1 was the highest, and that of group A2 were next, while that of group A4 and A2 were the lowest. Compared with group A1, expression level of H-FABP gene of group A2, A4 and A3 were decreased 17.45%,55.56% and 60.32%, respecticely (0.01< P<0.05). And the expression level of FAS gene of group A1 was increased by 20.72%, 44.09% and 47.25% compared with group A2, A4 and A3, respectively.In summary, there was a positive effect on the production performance and the slaughtering performance of Dazu black goat by increasing the dietary concentrate level, moderately. On the other hand, it could facilitate the fat deposition of muscles and also improved the meat quality with increasing the dietary concentrate level, properly. |
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