Application Of Dietary Glycerol Monolaurate In Broilers And Laying Hens

Glycerol monolaurate(GML)is a multi-functional food additive with emulsifying,anti-bacterial and anti-virus activities.GML can also be used as a feed additive to emulsify,to prevent mildew of feed,and to promote the growth and health of animals.In this study,GML was added to the diet of broilers and laying hens to explore the effects of GML on the production performance,the meat and egg quality,the feed digestibility and the health status of the husbandry animals at different feeding phases and of different densities,so as to provide theoretical foundation for the application of GML on broilers and laying hens.The main findings are as follows:(1)Effects of the single dose of GML addition on broilers:Compared with the control group,150 mg/kg GML group significantly increased the feed conversion rate,significantly increased the intestine length,the ratio of villus to crypt and the villus length,and significantly increased the nutrient apparent metabolic rate of crude protein,Cu and Ca.Moreover,the ratios of linolenic acid(C18:2),arachidonic acid(C20:4),essential fatty acid(EFA)and polyunsaturated fatty acid(PUFA)in chicken meat and the contents of crude protein,lysine,aspartic acid,glutamic acid,tyrosine,flavor amino acids and total amino acids are also significantly increased.The results showed that the addition of 150 mg/kg GML to the basal diets could promote the growth performance,digestibility and nutritional value of chicken meat.(2)Effects of different doses of GML additions on broilers:Compared with the control group,150,300 and 450 mg/kg GML groups significantly increased the average final weight and the average daily gain in broilers at higher density,significantly decreased the drip rate of leg muscles.150 mg/kg GML group significantly decreased the water content in breast muscles,and significantly increased the ratio of EFA and PUFA.300 mg/kg GML group significantly increased the average feed intake at higher density,the content of high density lipoprotein-cholesterol(HDL-C)in serum and the content of crude protein in chicken meat,and the ratios of EFA and PUFA in chicken meat,and significantly decreased the ratio of PUFA:saturated fatty acid(SFA)in chicken meat.450 mg/kg GML group significantly increased the total eviscerated rate and the content of crude protein in chicken meat,and significantly decreased the drip rate of breast muscles and the activity of alanine aminotransferase(ALT)in serum.The results showed that adding different doses of GML could improve the growth performance,carcass quality,muscle quality,serum biochemical indexes and nutritional components of chicken meat.(3)Effects of different doses of GML additions on laying hens during the late laying peak period:Compared with the control group,150,300 and 450 mg/kg GML groups significantly increased the average egg weight and feed conversion ratio,the spleen index,the thymus index,the villus length and the ratio of villus to crypt of jejunum,the ratio of PUFA:SFA in egg yolk,the content of histidine in albumen,and significantly decreased the content of triglyceride(TG)in serum,the content of SFA in egg yolk,the average area,average circumference and average volume of fat cells.300 mg/kg GML group significantly increased the albumen height,the Haugh unit,the yolk color,the content of crude fat in egg yolk and the contents of protein and glutamate in albumen.450 mg/kg GML group significantly increased the contents of HDL-C and total protein in serum and significantly decreased the activity of aspartate aminotransferase(AST)in serum.150 and 300 mg/kg GML groups significantly increased the ratio of polyunsaturated fatty acids(MUFA)in yolk.300 and 450 mg/kg GML groups significantly increased the laying rate,the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px),and significantly decreased the contents of the total cholesterol(TC),low density lipoprotein-cholesterol(LDL-C),total bilirubin,malondialdehyde(MDA),the activity of ALT in serum and the abdominal fat rate.The results showed that adding different doses of GML had a positive effect on production performance,egg quality,serum biochemical indexes,jejunum structure,abdominal fat morphology and egg nutritional quality of laying hens during the late laying peak period.(4)Long term effects of different doses of GML on laying hens:Compared with the control group,300 mg/kg GML group significantly increased the laying rate,average egg weight and feed conversion rate of laying hens.At the age of 58 week,150 mg/kg GML group significantly increased the eggshell thickness and eggshell strength,and 300 mg/kg GML group significantly increased the eggshell strength.At the age of 69 week,150,300 and 450 mg/kg GML groups significantly increased the eggshell thickness and eggshell strength.Moreover,150,300 and 450 mg/kg GML groups significantly increased the ratio of villus to crypt of jejunum,foaming capacity(FC),foaming stability(FS),initial denaturation temperature(T0)and the gel hardness of the albumen and the stability of the albumen emulsion,and significantly decreased the activity of AST,the content of TC in serum and the creaming index of the albumen emulsion.300 and 450 mg/kg GML groups significantly increased the content of HDL-C and significantly decreased the content of LDL-C and the activity of ALT in serum.The results showed that adding different doses of GML for a long time(53 weeks)had a positive effect on improving laying performance,egg quality,serum biochemical indexes,intestinal structure and albumen processing performance in laying hens.The effect was better at the later egg-laying stage.(5)On broilers,the addition of 300 mg/kg GML is recommended for higher breeding density.On laying hens,it is advisable to use GML at the late period of egg production,and the addition of 300 mg/kg GML is better for improving laying performance and egg quality,while the addition of 450 mg/kg GML is better for improving the health status of laying hens.In summary,GML has broad application prospects to be a safe,efficient and versatile feed additive in broilers and laying hens.