Effects Of Stocking Density On The Growth,Meat Performance,and Welfare Of Geese

Stocking density has an important influence on the growth,product quality and welfare of geese.With the rapid development of the poultry industry,many producers adopt the highest possible stocking density in production,as the economic benefit per square meter is often higher if the birds are stocked more densely.However,it is not clear whether an excessively high stocking density will influence the performance,health and welfare of goose,this research was conducted to evaluate the effects of stocking density on geese,and establish a standard for the stocking density of geese.336 28-day-age goslings were randomly allotted to 30 pens according to 5 different stocking densities:2 birds/m2,3 birds/m2,4 birds/m2,5 birds/m2,and 6 birds/m2.The method of controlling stocking density is to raise numbers of geese in pens with certain pen areas of 2.67 to 3 m2.Each treatment was represented by six replicates.The whole experiment lasted 42 days.Feather performance was assessed by two types of measurements:back-feather damage rate,and feather contamination degree which was carried out by feather scoring.Walking ability was assessed by gait scoring.All birds in each pen were individually scanned for back-feather damage measurement at 42 days of age.From 60 to 65 days of age,three geese from each pen were randomly selected and tagged for behavioral observation.At 68 and 69 days of age,all birds in each pen were individually scored for gait.At 69 days of age,one bird from each pen was randomly selected for feather scoring.The higher the feather score and the gait score,the worse the goose welfare.At 70 days of age,two birds from each pen was randomly selected,their blood samples were collected from wing venepuncture for the measurements of Heterophil:Lymphocyte ratios(H:L)and serum parameters,and their body size were measured,after which they were sacrificed immediately by exsanguination and dissected to determine the carcass traits,meat quality,immune organ parameters and small intestine parameters.The results showed that:1.Stocking density will significantly influence the growth and development of geese:as the stocking density increased,the goose body weight decreased,feed/gain ratios increased,and the primary feather length decreased.To be compared with 2 birds/m2 group,the body weights at 42 d(P<0.001)and 70 d(P<0.001)of 6 birds/m2 group were reduced by 10.53%and 10.43%respectively,the feed/gain ratios for 28 to 42 day period and 28 to 70 day period of 6 birds/m2 group were increased by 16%(P = 0.001)and 11.58%(P<0.001),respectively,,the primary feather lengths at 42 d(P<0.001)and 70 d(P = 0.021)of 6 birds/m2 group were reduced by 20.38%and 6.62%respectively.Moreover,the jejunum index,ileum index,and small intestine index,and the lengths of the jejunum,ileum,and small intestine were all adversely affected(P<0.05)when stocking density was increased to 6 birds/m2.In addition,serum concentrations of alkaline phosphatase(P = 0.013)and triiodothyronine(P<0.001)decreased as the stocking density increased.The serum thyroxine concentration of geese from the 6 birds/m2 group was lower than that of geese from the other groups(P<0.05).These results indicated that excessive stocking density will conversely influence the growth performance,feather growth,intestinal development,and thyroid function of geese.2.Stocking density will significantly influence the carcass traits and meat quality of geese:the percentages of leg and breast muscle of the geese in 5 birds/m2 and 6 birds/m2 groups were all lower than those of 2 and 3 birds/m2 groups(P<0.05),whereas the centrifuging loss rate of leg and breast muscle of the geese in 5 birds/m2 and 6 birds/m2 groups were both higher than those of 2 and 3 birds/m2 groups(P<0.05);When geese were in 6 birds/m2 group,their a-value of leg muscle was lower than that of other groups(P<0.05),their a-value of breast muscle was lower than that of 2 birds/m2 and 4 birds/m2 groups(P<0.05),their b-value of breast muscle was higher than that of 3 birds/m2 and 5 birds/m2 groups(P<0.05),and their centrifuging loss rate of breast muscle was higher than the other groups(P<0.05).These results indicated that when the stocking density was 5 or more birds/m2,the percentages of leg and breast muscle,and the meat quality of geese were all significantly decreased.3.Stocking density will significantly influence the welfare status of geese:when stocking density was 4 or more birds/m2,standing on one leg(relaxing)behavior reduced significantly(P<0.05);when stocking density was 5 or more birds/m2,feather contamination degree(P<0.05),preening behavior(P<0.05),and H:L value(P<0.05)all increased significantly;when stocking density was 6 birds/m2,the behaviors of lying and feather pecking,and back-feather damage rate all increased(P<0.05,for all),whereas walking ability declined,which was reflected by the decreased proportion of geese with normal gait(P<0.05)and the increased proportion of geese with gait problems(P<0.05).The results also showed that thymus weight of 2 birds/m2 group was significantly higher than that of 4,5,6 birds/m2 groups,whereas the IL-2 concentration in serum of 6 birds/m2 group was significantly lower than that of 2,3,5 birds/m2 groups(P<0.05).These results indicated that high stocking density(5 or more birds/m2)will lead to poor welfare(including poor feather performance,poor gait and an increase in the frequency of abnormal behavior and poor immune function),which was harmful to the growth and production performances of geese.Based on the results above,it can be concluded that when geese were reared in plastic net-floor pens,the stocking density should be less than 5 birds/m2 to avoid the converse effects of excessive stocking density on the goose growth and goose production.