Background: Practices such as the establishment of monocultures, the use of herbicides and overgrazing in tropical cattle ranching have led to deforestation and soil degradation in extensive areas of natural vegetation, causing local and global environmental consequences. In the state of Yucatán, different actors have created initiatives to avoid these consequences through the design, dissemination and implementation of sustainable practices among cattle producers. Objective: This paper seeks to understand how the structure of institutional networks affects the dissemination of sustainable livestock practices for the management of water, soil, biodiversity, forage and animals, which favor a transition to sustainability for the livestock sector in Yucatan. As a case study, the project coordinated by the Universidad de Yucatan for the establishment of intensive silvopastoral systems (ISPS) is analyzed, particularly the scope of the project to transform the practices of livestock farmers in the state of Yucatan and the role played by institutions linked to livestock issues to promote or obstruct this transformation. Methodology: The research was carried out by means of interviews with actors identified by their position in the different institutions linked to cattle raising.
Background. In seasonally anovulatory goats, sexually active bucks led a high pregnancy rate during a mating period of 36 days. Progesterone priming of does can reduce the length of the mating period while maintaining high fertility by allowing oestrous behaviour at the first male-induced ovulation. Objective. To determine whether high fertilization rates could be achieved by using two sexually active bucks, alternated daily for a period of seven days in four successive groups of does. Methodology. Two control bucks were used only with one group of does (n = 19), whereas two experimental bucks were successively housed with four groups of does (n = 18 or 19 each). One of the control and experimental bucks was introduced to their respective groups in the morning and removed 24 h later to rest for 24 h. Immediately after the removal of the first buck, the second buck was placed with the group of does. Each doe was treated with 25 mg of progesterone im 48 h prior to the first introduction of bucks to reduce short ovulatory cycles. Results. In each group, the proportion of does that ovulated was higher than 93%. These proportions did not differ among groups exposed to the control or experimental bucks (P > 0.05). In each group, the proportion of pregnant does was higher than 78%; proportions did not differ among groups (P > 0.05). Implications. At farms with few bucks, efficient management of sexually active bucks can yield a high percentage of pregnant females. Conclusion. These results indicate that two sexually active bucks housed with four successive groups of progesterone-treated anovulatory does during a mating period of seven days were able to achieve high pregnancy rates.
Background: Native fish species are a developing alternative for sustainable aquaculture worldwide and in Mexico, the southern region is leading the efforts in freshwater species. Objective: To assess the effect of different stocking densities on the productive performance of native fish juveniles of blackstripe cichlid (Vieja fenestrata). Methodology: A one-factor randomized experimental design was used, evaluating in triplicate four stocking densities, 0.5 (L), 2 (M), 4 (H) and 6 (S) juvenile L-1. The experiment lasted 30 days. Wet weight and total length were registered every 15 days and growth performance indices were obtained. Results: Growth and survival were superior (P<0.05) for densities L and M. However, the M density showed a higher (P<0.05) growth rate, weight gain, and condition factor. Implications: The stocking density showed an apparent effect on the growth and survival of juveniles of the blackstripe cichlid, with the M density showing the best results; however, a cost-benefit assessment is required before starting production of this tropical native species. Conclusion: Our results suggest that a territorial and/or food competition was probably responsible for the survival and growth obtained. Although more studies are required, it appears that Vieja fenestrata showed the typical patrons of behaviour of another most famous cichlids, as Nile tilapia, with high levels of aggression that depend on stoking density.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：