Abstract
The objective of this study was to evaluate the effect of different hormonal protocols on the reproductive performance of Santa Inês ewes in Amazon environmental conditions. Twenty-two Santa Inês ewes between 3 and 4 years-old were distributed in a randomized block experimental design, where the treatments consisted of two protocols for estrus synchronization (short and long) with eleven animals each. Data on the occurrence of estrus were described for each protocol. Data of estrus, pregnancy, and prolificity were firstly subjected to ANOVA and a subsequent Tukey’s test. Results were considered significant at p ≤ 0.05. The short-term protocol presented an interesting successful rate, where above 70% ewes tested had estrus. The long-term protocol also achieved a high successful rate, where above 80% ewes tested had estrus. However, comparing the protocols, the long-term protocol presented better results of positive estrus and pregnancy rates in ewes. Thus, it can be concluded that both protocols presented satisfactory results regarding estrus manifestation, and prolificity (lambs produced per ewe). However, under Amazon environmental conditions, the long-term protocol presented better results regarding positive manifestation of estrus and pregnancy rate.
Highlights
Reproduction is important for animal production, in order to maintain the production system continuation
Estrus synchronization or induction is an interesting tool for increasing the pregnancy rate in ewes
There are other problems related to the period of the sponge remaining inside the vagina due to the variations in progesterone concentration during the protocol used (Holtz, 2005; Sidi et al, 2016), besides other hormones
Summary
Reproduction is important for animal production, in order to maintain the production system continuation. Modern ewe husbandry has improved the efficiency of extensive production and controlled the reproductive process for intensive production. The synchronization of estrus in ewes focuses on the manipulation of the estrus cycle (Zonturlu, Özyurtlu, & Kaçar, 2011), the manipulation of either the luteal or the follicular phase of the estrus cycle. In this sense, hormonal treatment to control ovulation and reproduction is an interesting alternative for successful breeding and increasing the number of pregnant females (Abdalla, Farrag, Hashem, Khalil, & Abdel-Fattah, 2014). Applications of exogenous hormones for increased reproductive performance in domestic ewes usually focus on estrus synchronization (Najafi, Cedden, & Maleki, 2014)
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