This study investigated the effects of the inclusion of oat-ryegrass silage (ORGS) in combination with maize silage (MSLG) in four treatments: T1 = 100 % ORGS, T2 = 67 % ORGS/33 % MSLG, T3 = 67 % ORGS/33 % MSLG, and T4 = 100 % MSLG to milking cows on continuous grazing with 4.7 kg DM of commercial dairy concentrate 18 % CP. Daily milk yield and composition, live weight, body condition score, and chemical composition of feeds were recorded during the last 4 days of the experimental periods. Feeding costs were calculated by partial budgets. Eight Holstein lactating cows were used in a replicated 4 × 4 Latin square, with 14-day periods. There were no statistical differences (P > 0.05) for milk yield (mean 15.5 ± 5.0 kg/day/cow) or composition (mean milk fat 34.6 ± 4.4 g/kg, protein 32.4 ± 3.1 g/kg, lactose 46.9 ± 1.6 g/kg), milk urea nitrogen (11.3 ± 2.1 mg/dl), live weight (434 ± 38 kg), or body condition score (2.4 ± 0.15). The silage cost of ORGS was 2.5 times higher than MSLG, so the feeding cost in T1 was 26 % higher per kilogram of milk than for T4, with T2 and T3 as intermediates. ORGS can be a substitute to maize silage in the proportions studied, although feeding costs were higher.

Oaxaca cheese is a typical Mexican product of the pasta filata group. In spite of the importance of this cheese, it has been scarcely studied. The objective of this study was to document the method of manufacture and its physicochemical characteristics. There are variations in the process of manufacturing and has been affected by external influences such as time and temperature. There were variations in the physicochemical characteristics as the processes were not standardised, the variations being in protein from 150.3 to 241.5 g/kg; in fat from 170 to 253.3 g/kg; in pH from 4.9 to 5.8; in salt from 8.4 to 36.2 g/kg; in moisture from 124.1 to 610.3 g/kg and in ashes from 18 to 41.8 g/kg.

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The use and management of native grassland for dairy production during the rainy season was studied on two small-scale dairy farms in the highlands of central Mexico. Two stocking rates (2 and 4 cows/ha) and two levels of supplementation with commercial concentrate (4 and 6 kg/cow/day) under grazing were given to 12 milking Holstein cows in a 4 × 4 Latin square design replicated three times in a factorial arrangement. Net herbage accumulation (NHA), sward height, chemical composition, and in vitro digestibility of organic matter were recorded for the grassland, as well as vegetation cover and herbage mass 12 weeks post experiment. Animal performance variables were milk yield and composition, live weight, and body condition score. A partial budget analysis of feeding costs, returns, and margins was calculated. There were no differences between periods for NHA and herbage height and between plots for chemical composition (P > 0.05). However, there were highly significant differences among periods (P < 0.01) for organic matter, neutral detergent fibre (NDF), acid detergent fibre, in vitro organic matter digestibility (IVOMD), and estimated metabolisable energy (eME), with highly significant plot × period interactions (P < 0.01) for NDF, IVOMD, and eME. There were no statistical differences (P > 0.05) between treatments for milk yield, chemical composition of milk, live weight, or body condition score. Post-experimental vegetation cover was 72 % for both stocking rates, indicating there was no degradation of the grassland. Lower feeding costs were for the low supplementation treatments. It is concluded that a high stocking rate in studied native grasslands of 4 cows/ha with moderate concentrate supplementation supports a mean milk yield of 11.9 kg/cow/day during the rainy season without deleterious effects on the grassland.

No abstract

RESUMENLa fermentación anaeróbica de los carbohidratos estructurales en el rumen de los bovinos genera productos de desecho como ácidos grasos volátiles, calor de fermentación, bióxido de carbono y gas metano. Este último es un gas de invernadero que tiene un potencial varias veces mayor que el CO 2 para inducir calentamiento global. El objeto del presente trabajo es aportar una estimación del inventario nacional de metano producido por la fermentación entérica del ganado bovino en México, realizado a partir del uso de un modelo matemático de simulación. Se hizo una clara diferenciación entre el CH 4 producido por bovinos que consumen una dieta típica de las regiones tropicales y aquellos que se alimentan con ingredientes de las regiones templadas de México. Se estimó que la emisión total de metano producido por las 23.3 millones de cabezas de bovinos de México asciende a aproximadamente 2.02 Tg/año. Se concluyó que el modelo desarrollado fue apropiado para producir una mejor estimación del inventario nacional de metano producido por el ganado bovino, ya que es lo suficientemente flexible para incorporar nuevos grupos de ganado o esquemas de clasificación, niveles de productividad y una gran variedad de alimentos para el ganado. El modelo también puede utilizarse para evaluar diferentes escenarios de mitigación y servir como herramienta para diseñar políticas de mitigación. ABSTRACTAnaerobic fermentation of structural carbohydrates in the rumen of bovines produces waste products such as volatile fatty acids, fermentation heat, carbon dioxide and methane gas. Methane is a greenhouse gas having several times the global warming potential of CO 2 . The purpose of the present paper is to provide a realistic estimate of the national inventory of methane produced by the enteric fermentation of cattle, based on a simulation model and to provide estimates of CH 4 produced by cattle fed typical diets from the tropical and temperate climates of Mexico. Predicted total emission of methane produced by the 23.3 million heads of cattle in Mexico is approximately 2.02 Tg/yr. It was concluded that the modeling approach was suitable in producing a better estimate of the national methane inventory for cattle. It is flexible enough to incorporate more cattle groups or classification schemes, productivity levels and a variety feed ingredients for cattle. The model could also be used to evaluate different mitigation strategies and serve as a tool to design mitigation policies.

Tropical grasses are the primary nutrient resource for cattle production in the tropics, and they provide low-cost nutrients to cattle. However, its production is constrained by seasonal changes and quality; hence, appropriate usage of relatively inexpensive agricultural by-products is important to profitable livestock production. The objective of the study was to evaluate the effect of supplementing coffee pulp to dairy cows grazing tropical grasses on milk yield and forage intake. Four multiparous crossed Holstein-Brown Swiss-Zebu cows of similar weight and milk yield were used. The effect of 10%, 15% and 20% inclusion of coffee pulp in dairy concentrates on milk yield and forage intake was analysed using a 4 × 4 Latin square design. Results showed that there were no significant effects (P > 0.05) in grass dry matter intake, milk yield, milk composition body weight and body condition score due to the inclusion of coffee pulp in the dairy concentrates. It is concluded that coffee pulp can be included at levels of 20% in the concentrate without compromising significantly (P > 0.05) milk yield, milk composition and grass dry matter intake. It also was concluded that cost of concentrate is reduced in 20% by the inclusion of coffee pulp.

The objective of the present study was to determine the diversity and causative factors in the textural profile of the Artisan Ranchero Cheese (ARC), a popular soft cheese made with raw cow's milk, which is consumed fresh. These factors included climatic conditions, production zone, cheese supplies, cheesemaking procedure and chemical attributes. Texture attributes were determined using texture profile analysis method. The relationship between texture and chemical attributes of the ARC were determined by a Factor Analysis. An Agglomerative Hierarchical Clustering Analysis was used to differentiate the ARC manufactures into groups. Two groups were identified, production zone being the variable which explained the variation in the data. Finally, a Discriminant Analysis was performed to determine standardisation of the ARC attributes through the sampling periods. The 89% of cheese samples were correctly classified into their own cheese manufacture. This last analysis demonstrated that there was an important degree of standardisation of the cheesemaking procedure within each cheese manufacture, something that was not demonstrated before with artisan cheesemakers.