Thomaz Cyro Rodrigues - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
Isis Nicory - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
Henry Alba - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
Gleidson Carvalho - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
Manuela Tosto - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
Rodrigo Bittencourt - School of Veterinary Medicine and Animal Science/Federal University of Bahia, Salvador City, Bahia State, ۴۰.۱۷۰-۱۱۰, Brazil
José Augusto Azevedo - Department of Agricultural and Environmental Sciences of the State University of Santa Cruz, Ilhéus City, ۴۵.۶۶۲-۹۰۰, Brazil
Lays Mariz - Department of Animal Science, Federal University of Ceara, Fortaleza City, Ceara State, Brazil
Stefanie Santos - Department of Animal Science, Federal University of Ceará, Fortaleza City, Ceará State, ۶۰۳۵۶-۰۰۱, Brazil

The objectives of this study were ۱) to compare models to describe the lactation curve of the Saanen, Moxotó, and Anglo-Nubian ۲) to evaluate the effect of genetic groups on production and composition milk and efficiency of mobilization of body reserves during lactation. Twenty-three multiparous goats, newly calved, were divided into three treatments (genetic groups: ۹ Saanen, ۸ Moxotó, and ۶ Anglo-Nubian). The goats were randomly distributed in collective pens, under the same feeding conditions. Five mathematical models were used to adjust the lactation curves: Wood (WD); Papajcsik and Bodero (PB); Adapted from Papajcsik and Bodero (APB); Nelder (ND) and Wilmink (WM). To indicate the best fit, the model evaluation system software was used, performing additional analyzes with the observed and predicted values ​​for each fitted equation. There were differences (P<۰.۰۵) in the parameters a, b and c between the genetic groups in each mathematical model. The APB model is recommended for use in all genetic groups to evaluate milk yield (Y), following the parameters: Y = ۱.۱۹۶+۰.۰۵۴۵×t×e (-۰.۰۳۸×t) for Saanen, Y = ۰.۲۹۷+۰.۰۳۱×t×e(-۰.۰۴۶۲×t) for Moxotó and Y = ۰.۷۵۷+۰.۰۵۵۴×t×e(-۰.۰۴۱۷×t) for Anglo-Nubian. The results for average milk production during ۲۷ weeks of lactation were ۱.۳۷; ۰.۳۷ and ۰.۹ kg d-۱ for Saanen, Moxotó and Anglo-Nubian, respectively. Except for lactose, there was a difference (P<۰.۰۵) between the genetic groups for milk composition and plasma beta-hydroxybutyrate (BHB) levels. Considering milk composition, the Saanen, Moxoto and Anglo Nubiana presented the averages (%) for fat of ۳.۶۶, ۶.۷۵, and ۵.۱۰, protein ۳.۳۲, ۴.۹۷, and ۴.۱۸ and lactose ۴.۲۸, ۴.۴۶, and ۴.۳۹%, respectively. There was no effect (P>۰.۰۵) on B-HBO in response to days of lactation, but Saanen and Anglo Nubian goats had higher plasma levels of this metabolite compared to Moxotó goats. Saanen had a greater weight loss of ۱۲.۸۳ kg, which was verified at ۳۵ days of lactation. Saanen and Anglo-Nubian animals have a greater ability to mobilize body reserves compared to Moxotó. APB model is adequate to describe milk production of goats in tropical areas.

Anglo-Nubian, beta-hydroxybutyrate, body weight change, Moxotó, Saanen