| China is a big country of goose raising,and has a long history of it,and also has a large number of local breeds.Magang goose is a well-known local breed in China and one of the four famous breeds in Guangdong,with a market share of 70%,and is the main breed for making Guangdong roast goose.However,traditional Magang geese are reared in the waterfront,which is polluting to the aquaculture water and also brings a food safety risk.In recent years,dry raising of waterfowl has become a trend,but the research on dry raising of Magang goose is rarely reported.In this context,this experiment adopts the whole dry-raising method to explore the early growth and development of Magang geese under dry-raising conditions and the effect of dry-raising on meat quality,so this thesis aims to provide a theoretical cornerstone for the large-scale production and dry raising mode of Magang geese.The experimental geese were selected from the origin of Magang goose,Magang Town,Kaiping City,Guangdong Province.500 geese were randomly selected from 2000one-day-old geese.By turning the anus,the males and females were identified and then we marked their wings and feet.Finally,400 healthy geese(half male and half female)were selected and randomly divided into four groups of 100 each and kept in four pens.For a rearing period of 13 weeks,we selected two pens and measured the geese’s growth and development each week.Fasted individuals were weighed and body measurements were taken regularly every Monday morning at 7 a.m.By calculating the average body weight of geese each week,we fitted the growth curve of geese using three growth curve models,Logistic,Von Bertalanffy and Gompertz,so as to explored the model which is suitable for the early developmental pattern of dry-raising Magang geese.At the 10th,11th,12th,and13th weeks of the experiment,40 Magang geese(including 20 male geese and 20 female geese)with consistent health were randomly selected for slaughter and measurement.In the 12th week of the experiment,12 Magang geese(6♂+6♀)with a median weight were randomly selected,and blood was collected and analyzed for blood biochemical indicators.The results of the study were as follows:1.Early growth performance of dry-raised Magang geeseThe body weights of male and female at 10 weeks and 12 weeks of age were 4066g,3509g,4206g and 3993g,respectively.Gompertz model can well simulate the weight growth curve(R~2≥0.995)of dry-raised Magang geese.The inflection point of age for male geese is 4.62 weeks,and its inflection point of body weight is 1740.71g,while the inflection point of age for female geese is 4.5 weeks,and its inflection point of body weight is 1423.47g.Before 6 weeks of age,the geese grow rapidly with relative growth rates above 20%,and weight growth is slow after 10 weeks of age.2.Slaughter performance and correlation analysis of dry-raised Magang geeseDressing Percentage of 12-week-old male geese was 91.89%,percentage of semi-eviscerated carcass was 80.26%,percentage of eviscerated carcass was 73.6%,pectoral muscle rate was 5.49%,and eviscerated carcass fat was 7.67%;the dressing Percentage of female geese was 92.26%,semi-eviscerated carcass rate was 85.04%,eviscerated carcass rate was 72.17%,pectoral muscle rate was 6.84%,and abdominal fat rate was 9.15%.Both male and female geese showed highly significant positive correlation(P<0.01)between body weight and carcass weight,semi-eviscerated carcass weight,eviscerated carcass weight,pectoral muscle weight and abdominal fat weight at 12 weeks of age.3.Meat quality and correlation analysis of dry-raised Magang gooseThe results showed that the pectoral shear force of 12-week-old dry-raised male Magang geese was 45.58N,p H was 6.06,and drip loss was 2.69%.The body weight of male Magang geese showed a highly significant positive correlation(P<0.01)with the shear force of meat quality;the pectoral shear force of female Magang geese was 43.97N,p H was 6.81,and drip loss was 2.61%.The weight of female Magang goose was significantly positively correlated with the shear force,p H and transverse section area of breast muscle(P<0.01),and there was a significant positive correlation between the semi diving length and the shearing force of meat quality(P<0.01).Week age(10 wk vs 12wk)significantly affected the shear stress,p H value and cross-sectional area of Magang geese(P<0.05),but it had no effect on drip loss for both male and female.There were no significant differences in the histomorphology of pectoral and leg muscles between sexes of Magang geese.There was a strong correlation between body size traits and meat quality,with a greater or lesser degree of correlation,positive or negative.4.Blood biochemical indexes and correlation analysis of dry-raised Magang geeseThere was no significant difference in ALT,AST,BUN,CRE,TP and Glu between male and female Magang geese at 12 weeks old.There was a significant positive correlation between blood glucose and total protein,aspartate aminotransferase and tibia length(P<0.01),a very significant negative correlation between glucose and chest width(P<0.01),and a significant positive correlation with chest depth(P<0.05).Chest width was significantly positively correlated with alanine transferase,creatinine and aspartate transferase(P<0.05).And there was a significant negative correlation between the cross-sectional area of pectoral muscle fibers(P<0.05).5.Research on the optimal week age of dry-raised Magang geese to the marketThe sensory evaluation of the pectoral muscles of Magang geese aged from 10 to 13weeks were good.From 10 weeks of age,there was no significant difference in sensory evaluation of pectoral muscles of male Magang geese,but as the age of the goose increases,the sensory evaluation of pectoral muscles of Magang geese increased as well.The appearance of living feathers of dry raised Magang geese aged from 10 to 11 has grown well,but there are still many black needle feathers on the carcass.As for the 12weeks old male geese,there are less needle feathers on the carcass,while there are still more needle feathers in female geese.As for the 13 weeks old geese,there are few needle feathers on the carcass of both male and female,which can meet the requirements of slaughter and market.According to the comprehensive analysis of the slaughter needle feather and muscle sensory evaluation,13 weeks old is the most suitable age for Magang geese to be raised on the market,with less needle feather and better meat quality. |
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