Impacto de diferentes sistemas alimentares na peripuberdade sobre a anatomo-fisiologia reprodutiva de borregas

Abstract

The onset of puberty and maintenance of reproductive function are physiologically dependent on nutrition. As a result, we hypothesize that nutritional variations may influence the metabolism and ability of peripubertal ewe lambs to reproduce. Thus, the objective was to investigate the influence of nutritional management in peripuberty (underfeeding and overfeeding) on the anatomo-physiology of the reproductive system of ewe lambs. The information from this study is presented in the form of a literature review for the production of an eBook and a scientific article. Literary search to make the eBook was carried out in the PubMed, ScienceDirect databases and the SciELO virtual library, referring to the years 2003 to 2021, in order to provide a literature review on the impact of nutritional management on the reproduction of ewe lambs. In the experiment of the scientific article, 25 lambs (7/8 Dorper), aged between 6 and 7 months, weighing from 15 to 25 kg (22 kg ± 0.89) were randomly selected and distributed into 3 groups. experimental: CG (Control group; n=8) with 100-110% of the consumption required by the National Research Council (NRC), G-Sub (Undernourished group; n=8) with a regime of 70- 80% of the required consumption and the G-Super (Supercharged Group; n=9) with 140% of the consumption required by the NRC. The lambs of the G-C and G-Sub groups were kept on pasture of Panicum maximum cv. Tanzania with access to water and mineral salt ad libitum and only the control group received 1.5% of live weight in commercial food, given twice a day. The G-Super lambs remained confined during the 8-month experimental period (April to November), receiving total diet, in the proportion forage: concentrate of 20:80, containing 16% crude protein (CP) and 72 % of total digestible nutrients (TDN), aiming at a daily weight gain of 200 g/day according to NRC, with access to water and mineral salt ad libitum. In the adaptation period (5 weeks), the lambs received 3.5% of the live weight of the total diet (hay + feed), and this percentage was increas. The onset of puberty and maintenance of reproductive function are physiologically dependent on nutrition. As a result, we hypothesize that nutritional variations may influence the metabolism and ability of peripubertal ewe lambs to reproduce. Thus, the objective was to investigate the influence of nutritional management in peripuberty (underfeeding and overfeeding) on the anatomo-physiology of the reproductive system of ewe lambs. The information from this study is presented in the form of a literature review for the production of an eBook and a scientific article. Literary search to make the eBook was carried out in the PubMed, ScienceDirect databases and the SciELO virtual library, referring to the years 2003 to 2021, in order to provide a literature review on the impact of nutritional management on the reproduction of ewe lambs. In the experiment of the scientific article, 25 lambs (7/8 Dorper), aged between 6 and 7 months, weighing from 15 to 25 kg (22 kg ± 0.89) were randomly selected and dis-tributed into 3 groups. experimental: CG (Control group; n=8) with 100-110% of the consumption required by the National Research Council (NRC), G-Sub (Undernour-ished group; n=8) with a regime of 70- 80% of the required consumption and the G-Super (Supercharged Group; n=9) with 140% of the consumption required by the NRC. The lambs of the G-C and G-Sub groups were kept on pasture of Panicum maximum cv. Tanzania with access to water and mineral salt ad libitum and only the control group received 1.5% of live weight in commercial food, given twice a day. The G-Super lambs remained confined during the 8-month experimental period (April to November), receiving total diet, in the proportion forage: concentrate of 20:80, containing 16% crude protein (CP) and 72 % of total digestible nutrients (TDN), aiming at a daily weight gain of 200 g/day according to NRC, with access to water and mineral salt ad libitum. In the adaptation period (5 weeks), the lambs received 3.5% of the live weight of the total diet (hay + feed), and this percentage was increased until reaching an average of 4.5 to 5% of the live weighted until reaching an average of 4.5 to 5% of the live weight. The bromatological analysis of the pasture was carried out every 21 days to evaluate the nutritional value and determination of the dry matter, mineral matter and crude protein contents. The lambs were weighed every 15 days to adjust their diet according to live weight, and blood samples were collected weekly to measure total cholesterol, triglycerides and urea, totaling 9 collections. Upon reaching a body weight of 32 to 45 kg, the ewes were synchronized by inserting a vaginal progesterone release device (CIDR®) for 12 days. Eight days after the removal of the CIDR, blood was collected to measure progesterone. Next, the ewes were slaughtered and the reproductive apparatus was removed for weighing, morphometric evaluation and sample processing for further analysis of the fractal dimension of the corpus luteum by the box-counting method and analysis of the percentage of the collagen area in slides of histological sections of corpora lutea stained with Picrosirius Red. Data were analyzed with the SAS program, considering a significance level of 5% (p=0.05). Nutritional management affected weight in G-Super, with higher final weight (p=0.0002) and weight gain (p=0.0006) when compared to G-C and G-Sub. G-Sub showed an increase in uterine weight (p=0.01) and number of cervical rings (p<0.05) compared to G-C and G-Super. Additionally, urea concentrations decreased in G-Sub compared to G-C and G-Super. Higher (p<0.05) concentration of cholesterol was identified at the beginning of the nutritional management in the lambs of the G-Super compared to the CG and G-Sub, in the intermediate period of the nutritional management, the CG showed an increase in the concentrations of cholesterol in compared to the G-Super and at the end of the nutritional management, the concentration of cholesterol increased in the lambs of the G-Sub compared to those of the GC and G-Super. G-Sub showed increased concentrations of triglycerides (p<0.05) compared to G-Super during the experiment. Progesterone concentrations (p=0.3039) were not affected by different nutritional managements. The fractal dimension increased (p=0.0013) in the corpora lutea of G-Sub compared to G-C and G-Super. There was no difference in collagen area (p=0.222) in the corpus luteum of the evaluated groups. Thus, we conclude that different nutritional managements in the months before puberty affect reproductive biology, blood metabolite concentrations and modify the structure of reproductive tissues of ewes.