| Primiparous blue foxes were studied in this experiment, which were fed with different dietary Met levels at the reproduction period. The effects of reproductive performance, digestive physiologyand serum biochemical parameters of blue foxes were investigated in order to provide a theoretical bas is for increasing the reproductive performance of primiparous blue foxes. This thesis was comprised of three trials:Experiment.1: This experiment was conducted to study the effects of dietary methionine level on nutrient digestibility, nitrogen metabolism and blood serum biochemical parameters in prepare breeding period of female blue foxes. One hundred and fifty health female blue foxes were randomly assigned into 5 groups with 30 replicates each group and 1 fox per replicate. The blue foxes in groupsⅠ, Ⅱ, Ⅲ, Ⅳ and Ⅴ were fed diet supplemented with 0.00%, 0.26%, 0.52%, 0.78%, 1.04% methionine, respectively. The pre-test lasted for 7 days and the trial lasted for 60 days. The results showed as follows: The digestibility of dry matter and the digestibility of crude fat were found no signif icant difference(P>0.05). The crude protein digestibility in group Ⅲ was significantly higher than in groupⅡand Ⅰ(P<0.05). The nitrogen intake of each group was found no significant difference(P>0.05). The fecal nitrogen in group Ⅴ was significant ly lower than in group Ⅱ(P<0.05)and the urine nitrogen in group Ⅲ and Ⅴ were signif icantly higher than in group Ⅱ(P<0.05). The nitrogen deposition in groupⅣ was extremely significantly higher than in group Ⅰand Ⅱ(P<0.01), the nitrogen deposition in group Ⅲ and Ⅴ was signif icantly higher than in groupⅠand Ⅱ(P<0.05). The AA digestibility increased with the increase of dietary Met(P<0.05). The Alt in group Ⅲ and Ⅳ were significantly higher than in group Ⅰ(P<0.05). The total protein in group Ⅲ was significantly higher than in group Ⅰ(P<0.05), and the serum concentration of ALB and GLOB had no signif icant difference(P>0.05). In conclusion, considering all indices of this experiment, when 0.52% methionine is supplemented in the protein diet with 29.31% protein level, that the intake of dry matter was 155g/d and the intake of methionine was 1.6g/d, the rate of nutrients and serum biochemical indexes of preparing breeding period female blue foxes was ideal.Experiment.2: This experiment was conducted to study the effects of dietary methionine level on reproductive performance of female blue foxes. One hundred and fifty healthy female blue foxes were randomly assigned into 5 groups with 30 replicates per group and 1 fox per replicate. The blue foxes in groupsⅠ, Ⅱ, Ⅲ, Ⅳ and Ⅴ were fed experimental diet supplemented with 0.20%, 0.45%, 0.70%, 0.95%, 1.20% methionine, respectively. The formal test lasted from February 10 th 20 14 to May 25th2014. The results showed as follows: the beginning of oestrus time of the blue foxes in groups Ⅱ, Ⅲ and Ⅳ was advanced, and ended earlier. The beginning of oestrus time in groups Ⅰ and Ⅴ was later. The difference between the little size and the survival rate in each group was not signif icant(P>0.05). The litter weight at birth showed a trend of decrease after the first increase as the methionine improved, and the litter weight at birth in groups Ⅰ and Ⅱ were significantly higher than the group Ⅴ(P<0.05). The survival rate in group Ⅱ was significantly higher than in group Ⅴ(P<0.01). The breeding rate in group Ⅱ was 17% higher than group Ⅰ, 10% higher than group Ⅳ, and 14% higher than group Ⅴ, but did not reach signif icant level(P>0.05). In conclusion, with the increase of methionine supplementation, the breeding rate, the conception rate, the litter weight of neonatal foxes and litter size increase first, and then decrease. When the protein level dur ing the service period and the gestation period was 32.7%, the basal diet supplemented with 0.45% Met, which the Met level in feed was 0.98%. The intake of DM during the service period and early pregnancy(pregnancy 1 to 15 d) was 150g/d, the Met intake was 1.5g/d; DM intake during pregnancy 16 to 45 d was 260 g/d, Met intake was 2.6 g/d;late pregnancy(pregnancy 46 d to calving) DM intake was 180 g/d, Metintake was 1.8 g/d, meet the requirement of female blue foxes.Experiment.3: The present study investigated the effects of dietary Met supplementation on reproduction performance, nutrient digestibility, nitrogen metabolism and serum biochemical indicators of female blue foxes. The trial selected sixty primiparous female blue foxes of breeding date, pedigree, age, weight etc. in approaching. The female blue foxes were randomly assigned to four groups(n= 15)(Met2, Met4, Met6, Met8) and fed a diet supplemented with either 2, 4, 6 or 8 g/kg Met, respectively. The experiment started on 10 th March and ended on 30 th June. Our data showed that individual body weight at 20 and 40 d in Met4 group was significant ly higher than in Met2 group(P<0.05). The Met4 group had the highest apparent digestibility of Dry Matter and Crude Protein compared to either th e Met2 or Met6 or Met8 group(P<0.05). The serum Met and Ile concentrations in Met4 group were signif icantly higher than in Met6 group or Met8 group(P<0.05). The results of this feeding trial indicate that supplemental Met plays an important role in reproduction perfor mance of female blue foxes. There are significant effects on growth performance of cubs. The data from this study indicate that improvements in reproduction performance are due to increased CP and DM and increased nitrogen retention. When the protein level was 40.56%, the intake of DM was 320g/d and the intake of Met was 3.2 g/d in the first twenty days of lactation and the intake of DM was 420g/d, the intake of Met was 4.2 g/d in the last twenty days of lactation, meet the Met requirement of female blue foxes and signif icantly improve the growing performance of cubs. |
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