Abstract
The aim of this study was to establish the morphologic and endocrine characteristics of luteal dynamics in goats. It was used Toggenburg female goats that showed natural estrus in a 48-hour interval. After estrus, ultrasonographic evaluations of the ovaries were daily performed during 21 days using a portable device (5MHz probe). Blood sample was collected for plasma progresterone (P4) determination. Corpora lutea were detected for the first time on day 5 and progressively increased in size until D9 (1.26 ± 0.08 cm²), with no variation on subsequent days. In females with one ovulation, the first visualization of the corpora lutea was earlier than in those with multiple ovulation (4.54 ± 0.18 vs 5.74 ± 0.25 days). At the moment of the first visualization, luteal area was smaller in animals with single ovulation. Plasma P4 concentration progressively increased until day 9 and it did not show significant increase until luteolysis, characterized by a sharp decrease in P4 concentration, reaching values below 1 ng/mL in 24 hours. The luteal area slowly and gradually decreased in size. It was observed a significant positive correlation between P4 concentration and area during luteogenesis and luteolysis (r = 0.63 and r = 0.50, respectively). When corpus luteum reached its maximum size (D9), female with more than one corpora lutea, with a greater luteal tissue area, did not show P4 concentration higher than those with one ovulation (5.92 ± 0.59 vs 7.04 ± 0.79 ng/mL). These results show that luteal dynamics in Toggenbur goats follow a similar pattern to those observed in other goat breeds and luteal tissue growth was positively correlated with corpora lutea functionality.
Highlights
The growth of goat industry in Brazil is stimulating the use of assisted reproductive technologies for this specie.the development of these techniques requires basic knowledge on ovarian physiology, which is still limited in small ruminants, especially when compared to other domestic species such as cows.Corpus luteum is a transitory gland responsible for sinthesys and release of progesterone (P4), a steroidal hormone essential for early embryo development and pregnancy support (Smith et al, 1994)
When corpus luteum reached its maximum size (D9), female with more than one corpora lutea, with a greater luteal tissue area, did not show P4 concentration higher than those with one ovulation (5.92 ± 0.59 vs 7.04 ± 0.79 ng/mL). These results show that luteal dynamics in Toggenbur goats follow a similar pattern to those observed in other goat breeds and luteal tissue growth was positively correlated with corpora lutea functionality
Despite the positive correlation observed between luteal tissue area and plasma P4 concentration during corpus luteum formation and regression periods, the results presented on Table 2 show that physiological capacity to synthesize and release P4 was not greater in those animals bearing more than one corpus luteum
Summary
The growth of goat industry in Brazil is stimulating the use of assisted reproductive technologies for this specie.the development of these techniques requires basic knowledge on ovarian physiology, which is still limited in small ruminants, especially when compared to other domestic species such as cows.Corpus luteum is a transitory gland responsible for sinthesys and release of progesterone (P4), a steroidal hormone essential for early embryo development and pregnancy support (Smith et al, 1994). The growth of goat industry in Brazil is stimulating the use of assisted reproductive technologies for this specie. The development of these techniques requires basic knowledge on ovarian physiology, which is still limited in small ruminants, especially when compared to other domestic species such as cows. Correct and accurate corpus luteum identification is crucial for the success of assisted reproduction programs. A positive correlation between luteal tissue area and concentration of plasma P4 was previously described for cows (Siqueira et al, 2009), sheep (Davies et al, 2006) and goats (Orita et al, 2000). The higher number of corpus luteum is not related to an increase in concentration of plasma P4 (Mann et al, 2007). Maximal plasma P4 concentration was related to the breed (Fonseca& Torres, 2005)
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