Ecosistemas y Recursos Agropecuarios

1-8

Authors: Verónica Rosales-Martínez, Juan Pablo Martínez-Dávila, Diego Esteban Platas-Rosado, Adalberto Rosendo-Ponce, Víctor Córdova-Ávalos

Migration is a survival strategy that is applied in situations of poverty, to lighten the problem of low salaries and inefficiently managed family needs. The purpose of this study was to compare the technological management of farming activities, applied by families before and after migrating, from 1979 to 2008 in the municipality of Jamapa, Veracruz. A survey was applied to 45 families with migrants, with a questionnaire of 115 closed questions, during the year 2009. Statistically significant changes were observed (McNemar, Chi2 = 18.91 and p < 0.001) with negative results for all technology used in activities related to maize, beans and cattle. The definition of a negative change was based on the fact that the technological elements that the producers used before migrating and no longer used afterwards were 265; the group of technological elements with a positive change, that is, which they did not use before and did use afterwards was 173. It may be concluded that migration has had a negative effect on maize (Chi2 = 122.49, p < 0.001) and bean (Chi2 = 98.09, p < 0.001) crops, and a positive effect on cattle ranching (Chi2 = 116.48, p < 0.001). Thus, the economy of families with migrants, in the agroecosystems of Jamapa, has improved, but the diversity of farm activities has decreased.

19-32

Authors: Yamilé Comabella, Andrés Hurtado, Javier Canabal, Tsai García-Galano

Hatching success, growth, development and survival of Cuban gar (Atractosteus tristoechus) larvae were examined at different temperatures (26, 28 and 30 ºC) up to 18 days after hatching (DAH). The time to hatching was inversely related to the incubation temperature (87, 100 and 111 h). Larval survival at the time of hatching was significantly lower at 30 oC (50.3 %), coinciding with the highest larval mortality (30.2 %). Growth rates were 1.75 mmd-1 -10.4 % d-1 at 26 ºC,1.30 mm d-1 -10.2 % d-1-1 at 28 ºC and 1.40 mm d-1 -10 % d -1 at 30 ºC. Three similar critical periods were identified: 0-6, 7-11 and 12-18 DAH. During the first period, a similar increase in weight and a significant increase in total length occurred, mainly at 30 ºC, indicating a more efficient reconversion of the yolk reserves. Later, growth was equally slow, corresponding with the transitional period from endogenous to exogenous feeding, indicating a similar physiologic pattern regardless of incubation temperature. Weight and length increased during the last period, with the greatest increase at 26 ºC in contrast with the lowest gain at 30 ºC. The inflexion points of many morphometric characters and the developmental stages accelerated with the increasing temperature. Although it was impossible to determine the optimal temperature, it was evident that 26 ºC favored hatching success and larval growth.

41-48

Authors: Gaspar Manuel Parra-Bracamonte, Ana María Sifuentes-Rincón, Williams Arellano-Vera, Juan Gabriel Magaña-Monforte, José Alberto Ramírez-De León, Gonzalo Velázquez

Beef tenderness is an important trait in consumer satisfaction and has been considered as the main trait for palatability, for which reason it is important to evaluate its variability in different cattle breeds. An experiment was designed to evaluate the Warner Bratzler Shear Force (WBSF) of Red Brangus cattle rib eye steaks and consumer acceptance. The tenderness of beef rib eye steaks was evaluated by the WBSF. A consumer preference evaluation test was carried out to quantitatively estimate tenderness, juiciness, flavor, doneness and general acceptance of the evaluated steaks. Mean WBSF was 5.03 kg ± 0.93 kg, theoretically indicating a tough beef. The distribution of the samples showed 21 % and 11 % of moderately tender and tender beef cuts, respectively. Cattle condition (bulls and steers) was not significant for the WBSF (p > 0.5). All the traits evaluated in the hedonic evaluation had approximately 6 points of a total of 8 (8 was best). Tenderness, juiciness and flavor presented a high and significant correlation (p < 0.5). None of the subjective traits was correlated with total acceptance. Under theoretical criteria, tender Red Brangus beef cuts are infrequent; however the beef has a good acceptance. Characterization studies may be necessary and useful to create marketing niches specific for this and other cattle breeds.

59-72

Authors: Rodolfo Ramírez-Valverde, Rafael Núñez-Domínguez, Enelvi Fabián-Barrios

The purpose of this study was to characterise papers on animal breeding published by Mexican researchers in the scientific journals that belong to the índice de Revistas Mexicanas de Investigación Científica y Tecnológica of the Consejo Nacional de Ciencia y Tecnología. The papers considered were published in the journals Agrociencia (n = 48), Revista Mexicana de Ciencias Pecuarias (n = 119), Tropical and Subtropical Agroecosystems (n = 17) and Veterinaria México (n = 78) up to the year 2012. Studies on animal breeding focused mainly on cattle, tropical zones and the states of Veracruz, México and Yucatán. Quantitative genetics was the most studied area and the most researched traits were those directly related to production. The most studied topics were phenotypical and environmental characterisations, estimations of genetic parameters, comparisons of genotypes, and methods to carry out genetic evaluations. Half of the research was published by two or more institutions and most (93 %) were prepared by two or more researchers (average 3.8 authors per article). The institutions with most published papers (64 %) in animal breeding were the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, the Universidad Nacional Autónoma de México, the Colegio de Postgraduados, the Universidad Autónoma Chapingo, the Universidad Autónoma de Yucatán and the Universidad Autónoma de Baja California Sur. The characterisation and analysis of the evolution of scientific publications are important in order to design animal breeding strategies and prioritise future research.

81-86

Authors: Juan Carlos García López, Juan Manuel Pinos Rodríguez, Gregorio Álvarez Fuentes, Marco Antonio Camacho Escobar, Yolanda Jasso Pineda

The use of mannan-oligosaccharides (MOS) was evaluated for coccidian control in broilers. Treatments: 1) Control: Nicarbazine (120 g t-1) and Salinomycin (66 g t-1); Bacitracin (55 g t-1); 2) Control + challenge; 3) MOS 1 kg t-1. Treatments 2 and 3 included oocysts (E. acervulina). Oocyst count was higher (p < 0.05) for broilers in T2 and T3. No lesions due to E. acervulina were recorded (p > 0.05). MOS may be used as an alternative to antibiotic growth promoters.