The aim of this study was to determine the socioeconomic, production characteristics and milk production cost of dual-purpose farms (DPF) oriented to milk production in a subtropical region of Central Mexico. The study focused on ten DPF that produce milk all year round, to gather socioeconomic characteristics of farmers (age, family structure, education level), farm resources (land holding, herd structure, infrastructure, management) and economic information during the year 2008. Family labour (FL) covers 66% of labour needs. The average milk production cost was US$0.21, fluctuating from US$0.19 to US$0.31 during the rainy and dry season, respectively. Supplements and hired labour (HL) accounted for 48 and 35% of milk production cost, respectively. Milk production generated daily incomes that covered daily operation costs of farms, as well as the economic needs of the farming family. Calves represented important incomes that ranged between 30 and 50% of total annual farm incomes, cashed in once or twice a year. Milk production provides economic stability to DPF, whereas FL and low input use are key elements that allow low costs in the production of milk and calves in DPF in Central Mexico.

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.

In vitro gas production with and without polyethylene glycol (PEG) of the fruits of Crescentia alata and Guazuma ulmifolia was evaluated, the degradation kinetics of lamb diets with added fruit of the tree was determined, and the ration intake and growth rate of lambs fed these diets were measured. Twenty-five entire male lambs of 23.5 ± 0.44 kg body weight were used and distributed in treatments: T0 (control without fruit); T1 and T2, 15 and 30 % of the fruit of C. alata; and T3 and T4, 15 and 30 % of the fruit of G. ulmifolia. Data variables chemical composition, fermentation kinetic, and digestibility in vitro were analyzed by a completely randomized design and data production response factorials design of five treatments by three evaluation periods. The total phenolic content (TP) (23.0 g/kg DM) was higher (P < 0.01) in the fruits of G. ulmifolia. The addition of PEG increased (P < 0.05) in vitro gas production (156.6 mL/g DM) in fruits of G. ulmifolia. In the fermentation kinetics, the total gas volume was higher (P < 0.01) at T0 (b = 293 mL/g DM), and the rate of degradation (c) but Lag time (t lag) was not different. In animal response, total dry matter intake was higher in lambs that received T4 (1.35 kg), and the daily weight gain and feed conversion did not differ (P > 0.05) among lambs receiving the treatments. Thirty percent G. ulmifolia fruit added in the diet increased dry matter intake and improved feed conversion but did not increase weight gain.

The aim of the present research was to evaluate the effect of Pithecellobium dulce, Tagetes erecta and Cosmos bipinnatus on methane emission, milk yield and dry matter intake in dairy cattle. A 4×4 Latin square experimental design was employed, using four multiparous Holstein cows of 553±72.4kg body weight, at mid lactation and average milk yield of 17.3±3kg/day. The experiment lasted 92 days, divided into four experimental periods of 23 days each. All cows had free access to maize and alfalfa silage in a 50:50 proportion, 4kg of concentrate/day and ad libitum access to water. Treatments consisted in supplementation of 0.5kg/day of the experimental plants, with one control treatment without supplementation. Each cow received one of each treatment in turn during one of the four periods. The C. bipinnatus reduced methane production by 16% (P<0,05) in comparison with the control diet. Milk production, milk composition and dry matter intake were not affected (p>0 0.05) by the use of C. bipinnatus or any other plant species. Supplementation at low doses of C. bipinnatus showed a reduction in ruminal methane production in dairy cows.

Liveweight gain was evaluated in tropical Dorper X Pelibuey lambs under intensive continuous grazing of native grasslands dominated by Paspalum notatum (PN) or Axonopus compressus (AC) in the subtropics of Central Mexico. Two trials were undertaken. Trial 1 lasted 12 weeks with 10 lambs (initial weight 18 +/- 2.57 kg, 3 months old) per treatment in 2002, and Trial 2 for 13 weeks with 8 lambs (initial weight 24.0 +/- 2.0 kg, 4 months old) per treatment. Lambs were weighed once per week, and liveweight change was estimated by linear regression over day of the experiment, using individual regression coefficients as unbiased estimates of daily liveweight change; analysed in a random block design. Lambs on Trial 1 gained 0.061 kg/lamb/day on PN and 0.047 kg/lamb/day on AC (P > 0.05) at an overall mean stocking rate of 25 lambs/ha. In Trial 2, liveweight gain was significantly larger in PN (0.060 kg/lamb/day) than on AC (0.043 kg/lamb/day) (P < 0.05), at a mean stocking rate of 21.5 lambs/ha. It is concluded that intensive continuous grazing of native grasslands in the subtropics of the highlands of Central Mexico enables moderate liveweight gains for weaned lambs during the rainy season; with better results in grasslands dominated by Paspalum notatum.