The effect of metformin on production performance and egg quality traits in laying hens

Introduction: Metformin is used in the treatment of infertility in women with polycystic ovary syndrome and insulin resistance. Metformin affects the release of GnRh and LH hormones by regulating the reproductive axis (Tosca et al. 2011). It has been shown that patients with polycystic ovaries who ovulate under metformin treatment have an improvement in ovarian artery blood flow and better dominant follicle and corpus luteum angiogenesis (Palumba et al. 2006). Egg laying in chickens is stopped at the end of production for several reasons. External and internal stimuli affect the hormonal levels of the hen's body, which causes changes in the conditions governing the laying organs (ovaries and oviducts), and these changes cause a decrease or stop of egg production. The purpose of using metformin in the diet of laying hens is to reduce the fat around the ovary, so that it can exert its positive effects (Toska et al. 2011). Chen et al. (2011) in Hy-Line laying Leghorn hens that received 30 or 100 mg/kg body weight of metformin significantly reduced egg laying rate, plasma triglyceride, cholesterol and insulin levels, body weight, abdominal fat, and liver fat content (Chen et al., 2011). In order to reduce fat reserves and improve egg laying at the end of production, this study was conducted in order to investigate the effect of metformin on production performance, external and internal quality traits of eggs in laying hens at the end of the production period (choosing the last weeks of production was due to reduced production and accumulation of abdominal fat)
Material and methods: The number of 64 laying hens of Leghorn breed HyLine-W36 at the 73 weeks of age were used in this experiment. The hens were allocated to 4 treatments (levels of 0, 50, 100 and 150 mg/kg body weight of Metformin) and four replicates with four birds in each replicate in a completely random design during 8 weeks of the experiment. In order to adapt to experimental diet and conditions, one week adaptation period was also done. Egg production performance including hen-day egg production, egg weight, egg mass, were recorder daily and feed intake of birds were measured and the feed conversion ratio (FCR) was calculated. At the beginning and end of the experiment, egg quality traits (egg length, egg diameter, shell weight, egg index, haugh unit, egg shell thickness, egg density, albumin weight, albumin pH, yolk height, yolk diameter, yolk weight, yolk pH, and yolk color) were evaluated and reported.
Results and discussion: The results of the experiment indicated that the production performance parameters including egg production, egg mass, egg weight, percentage of soft shell eggs, feed conversion ratio, feed efficiency, final weight of hens and weight gain of hens were not affected by treatments. Hens in the control group had the lowest percentage of cracked eggs (P<0.05). Egg length, egg width, shell weight, egg index, haugh unit, wide end shell thickness, middle shell thickness and egg density were not differed between treatments at the beginning and end of the experiment. The highest thickness of the thin end shell, both at the end of the experiment, was related to hens receiving metformin drug at 100 mg/kg body weight (P<0.05). Albumin height, albumin weight, albumin pH, yolk height, yolk width, yolk weight, yolk pH, and yolk color were not affected by experimental treatments at the end of the experiment. In general, the use of metformin drug in this experiment, could not have a positive effect on the performance and quality characteristics of eggs.

Introduction: Metformin is used in the treatment of infertility in women with polycystic ovary syndrome and insulin resistance. Metformin affects the release of GnRh and LH hormones by regulating the reproductive axis (Tosca et al. 2011). It has been shown that patients with polycystic ovaries who ovulate under metformin treatment have an improvement in ovarian artery blood flow and better dominant follicle and corpus luteum angiogenesis (Palumba et al. 2006). Egg laying in chickens is stopped at the end of production for several reasons. External and internal stimuli affect the hormonal levels of the hen's body, which causes changes in the conditions governing the laying organs (ovaries and oviducts), and these changes cause a decrease or stop of egg production. The purpose of using metformin in the diet of laying hens is to reduce the fat around the ovary, so that it can exert its positive effects (Toska et al. 2011). Chen et al. (2011) in Hy-Line laying Leghorn hens that received 30 or 100 mg/kg body weight of metformin significantly reduced egg laying rate, plasma triglyceride, cholesterol and insulin levels, body weight, abdominal fat, and liver fat content (Chen et al., 2011). In order to reduce fat reserves and improve egg laying at the end of production, this study was conducted in order to investigate the effect of metformin on production performance, external and internal quality traits of eggs in laying hens at the end of the production period (choosing the last weeks of production was due to reduced production and accumulation of abdominal fat)
Material and methods: The number of 64 laying hens of Leghorn breed HyLine-W36 at the 73 weeks of age were used in this experiment. The hens were allocated to 4 treatments (levels of 0, 50, 100 and 150 mg/kg body weight of Metformin) and four replicates with four birds in each replicate in a completely random design during 8 weeks of the experiment. In order to adapt to experimental diet and conditions, one week adaptation period was also done. Egg production performance including hen-day egg production, egg weight, egg mass, were recorder daily and feed intake of birds were measured and the feed conversion ratio (FCR) was calculated. At the beginning and end of the experiment, egg quality traits (egg length, egg diameter, shell weight, egg index, haugh unit, egg shell thickness, egg density, albumin weight, albumin pH, yolk height, yolk diameter, yolk weight, yolk pH, and yolk color) were evaluated and reported.
Results and discussion: The results of the experiment indicated that the production performance parameters including egg production, egg mass, egg weight, percentage of soft shell eggs, feed conversion ratio, feed efficiency, final weight of hens and weight gain of hens were not affected by treatments. Hens in the control group had the lowest percentage of cracked eggs (P<0.05). Egg length, egg width, shell weight, egg index, haugh unit, wide end shell thickness, middle shell thickness and egg density were not differed between treatments at the beginning and end of the experiment. The highest thickness of the thin end shell, both at the end of the experiment, was related to hens receiving metformin drug at 100 mg/kg body weight (P<0.05). Albumin height, albumin weight, albumin pH, yolk height, yolk width, yolk weight, yolk pH, and yolk color were not affected by experimental treatments at the end of the experiment. In general, the use of metformin drug in this experiment, could not have a positive effect on the performance and quality characteristics of eggs.