title: Reproductive and productive performances of Santa Inês ewes submitted to breeding in different periods of the Amazonian humid tropical climate.
abstract: The objective of this study was to evaluate the reproductive and productive performance of Santa Inês ewes bred at different times of the year in humid tropical climate. One hundred and forty-eight Santa Inês ewes were grouped according to the time of the year of their breeding season (i.e., mating period) (dry/wet, wet, wet/dry, and dry season). The service type was natural mating and the ewes and rams were kept together every night for 45 days. Reproductive efficiency was assessed by service, pregnancy, lambing, prolificacy, twinning, pregnancy loss, weaning, and lamb mortality rates. Ewes were weighed at the beginning and at the end of the breeding season and before and after parturition, and sequential weighing of the lambs was performed (at birth, 15, 30, 60, and 90 days). Reproductive efficiency index (number of lambs weaned/total of served ewes) and productive efficiency (kg of weaned lamb/kg of served or lambed ewes) were calculated. All ewes expressed estrus early in the breeding season; however, a higher percentage (53.5 and 7.1 % at 30 and 45 days, respectively) of ewes returned to estrus during the wet/dry period. The lower rates (13.9 %) of return to estrus at 30 days were during the wet season (P < 0.05). There were no (P > 0.05) effects of breeding seasons on the remaining reproductive rates. Ewes that lambed during the wet/dry transition period weighted less, before (40.5 ± 2.5 kg) and after (38.6 ± 1.6 kg) parturition, than those of other groups (P < 0.05). Lamb weight at birth did not vary between groups, however, weight at weaning was higher (15.6 ± 2.1 kg) in lambs born during the wet season (P < 0.05). The reproductive efficiency index was lower (0.66) when the breeding season took place during the dry/wet period (P < 0.05). Productive rates were significantly higher (0.29 and 0.33 for kg of weaned lamb/kg of served and lambed ewes, respectively; P < 0.05) in ewes served in the dry season. The reproductive performance of Santa Inês ewes was not significantly influenced by the period of the year in which the breeding seasons took place, allowing for four breeding seasons a year in the Amazon region. Variations between periods in return to estrus rates, weight of ewes close to parturition and lamb weight at weaning indicate that climate changes can also affect reproductive rates.
authors.affiliation: Institute of Animal Health and Production, Federal Rural University of Amazon, Belém, Pará, Brazil.
authors.forename: Felipe Nogueira
authors.initials: FN
authors.lastname: Soares
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil. m_emiliafraoli@yahoo.com.br.
authors.forename: Maria Emilia Franco
authors.initials: ME
authors.lastname: Oliveira
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Luciana Cristina
authors.initials: LC
authors.lastname: Padilha-Nakaghi
authors.affiliation: Department of Clinical and Veterinary Surgery, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Luís Guilherme
authors.initials: LG
authors.lastname: de Oliveira
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Marcus Antônio Rossi
authors.initials: MA
authors.lastname: Feliciano
authors.affiliation: Institute of Animal Health and Production, Federal Rural University of Amazon, Belém, Pará, Brazil.
authors.forename: Felipe Brener Bezerra
authors.initials: FB
authors.lastname: de Oliveira
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Pedro Paulo Maia
authors.initials: PP
authors.lastname: Teixeira
authors.affiliation: Department of Preventive Veterinary Medicine and Animal Reproduction, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, São Paulo, Brazil.
authors.forename: Wilter Ricardo Russiano
authors.initials: WR
authors.lastname: Vicente
authors.affiliation: Institute of Animal Health and Production, Federal Rural University of Amazon, Belém, Pará, Brazil.
authors.forename: Cristian
authors.initials: C
authors.lastname: Faturi
authors.affiliation: Institute of Animal Health and Production, Federal Rural University of Amazon, Belém, Pará, Brazil.
authors.forename: Luiz Fernando de Souza
authors.initials: LF
authors.lastname: Rodrigues
mesh_terms: D000818:Animals; D001947:Breeding / Q000706:statistics & numerical data*; D004971:Estrus; D005260:Female; D008297:Male; D036801:Parturition; D011247:Pregnancy; D012098:Reproduction; D012621:Seasons; D012756:Sheep; D034561:Sheep, Domestic / Q000502:physiology*; D014329:Tropical Climate; D014886:Weaning
keywords: Production; Reproduction; Sheep; Weather condition