RESUMEN
The Venezuelan Creole breed cow has shown great versatility in adapting to extreme tropical conditions, but unfortunately it has exhibited low fertility. In a previous study conducted at the Experimental Station Guárico in Calabozo, Venezuela, chromosomal analysis of 30 Creole bulls demonstrated the presence of Robertsonian translocation 1/29 (Rb 1/29) in 16.6% of the animals. Considering this finding, we sought to establish the incidence of Rb 1/29 in Creole cows. Thus, heparinized peripheral blood cells were cultured rendering metaphase spreads and were subsequently stained by Giemsa and G-banding techniques. The chromosomal diagnosis was performed in 2 groups of cows (21 pure Creole and 47 hybrids Creole x Brahman). The results confirmed the presence of Rb 1/29 in females as had already been demonstrated in bulls. In the first group of cows the incidence of Rb 1/29 was 4.8%; in the second it was 8.5%. The implication of this finding is discussed here.
RESUMEN
The Venezuelan Creole breed cattle is a Bos taurus well adapted to tropical conditions; however, it has demonstrated a low fertility rate. Recently, improvement in animal production by selection based on chromosomal analysis has allowed for the erradication of abnormalities involved in fertility problems, especially that of the 1 29 translocation. In the present work chromosomal analyses were carried out on 60 Creole bulls. Heparinized peripheral blood cells were cultured rendering metaphase spreads and subsequently stained by G- and C-banding techniques. The 1 29 translocation was observed in 13 of the 60 bulls. The occurrence of this translocation in Creole cattle is discussed.
RESUMEN
Eighteen mature estrous cycling beef cows and 9 prepuberal heifers were stratified by breed, age and weight to determine the effect of ovary-transplantation to a proximal site (right uterine horn) (U) and distal site (parotid region) (P) upon ovarian activity. Active ovaries (AO), ovaries with the corpus luteum (CL), were autotransplanted to the myometrium of the U in 3 cows and to the muscles of the P in 2 cows and their inactive ovaries (IO), ovaries without a CL, remained. Active ovaries of 6 cows were removed and heterotransplanted to 6 prepuberal heifers and their 10 were heterotransplanted to the U or the parotid (3). Six heifers received either a mature AO in the U or in the parotid. Three heifers were ovariectomized and their ovaries were heterotransplanted to 6 cows, 3 per site. Cows and heifers were slaughtered randomly 2 months after surgery and their ovaries were collected for microscopic and histological analysis. The transplants were successfully accomplished in 94% of the cows and in 83% of the heifers. Both of the unsuccessful heterotransplantations were located in the uterus. More estrous activity was found (P<.025) in cows than in heifers with their own ovaries in situ . All prepuberal ovaries in situ showed follicular development when mature AO were transplanted to either the U or parotid. The same trend was found in prepuberal ovaries transplanted to mature cycling cows. Cows with an IO in situ and AO transplanted to either site had more estrous activity than did ovariectomized cows with an IO transplanted to either site. Pregnancy rates in mature cycling cows with an least one ovary in situ were higher (P<.005) in cows with an ovary in the parotid region than cows with an ovary transplanted to the uterus.
