Julieta Gertrudis Estrada-Flores

Chemical composition and fermentation characteristics of grain and different parts of the stover from maize land races harvested at different growing periods in two zones of central Mexico

Abstract The objective of this work was to determine the rumen fermentation characteristics of maize land races used as foragein central Mexico. In vitro gas production (ml per 200mg dry matter (DM)) incubations were carried out, and cumulativegas volumes were fitted to the Krishnamoorthy et al. (1991) model. The trial used a split-plot design with cultivationpractices associated with maize colour (COL) as the main plot with three levels: white, yellow and black maize; growingperiods (PER) were the split plots where PER1, PER2 and PER3 represented the first, second and third periods,respectively and two contrasting zones (Z1 ¼ valley and Z2 ¼ mountain) were used as blocking factors. The principaleffects observed were associated with the maturity of the plants and potential gas production increased (P , 0·05) instems (PER1 ¼ 51·8, PER2 ¼ 56·3, PER3 ¼ 58·4ml per 200mg DM) and in whole plant (PER1 ¼ 60·9, PER2 ¼ 60·8,PER3 ¼ 70·9ml per 200mg DM). An inverse effect was observed with fermentation rates in leaves (P , 0·01) with0·061, 0·053 and 0·0509 (per h) and in whole plant (P , 0·05) with 0·068, 0·057, 0·050 (per h) in PER1, PER2 andPER3 respectively. The digestibility of the neutral-detergent fibre (NDF) decreased with maturity especially in leaves(P , 0·05) with values of 0·71, 0·67 and 0·66g/kg; in rachis (P , 0·01) 0·75, 0·72, and 0·65 in PER1, PER2 and PER3respectively. The NDF content in leaves in leaves (668, 705 and 713g/kg DM for PER1, PER2 and PER3,respectively), stems (580, 594 and 644g/kg DM) and, husk (663, 774 and, 808g/kg DM) increased (P , 0·05) withincreasing plant maturity, rachis were significantly different between periods (P , 0·01). The structure with the bestnutritive characteristics was the husk, because it had the lowest fibre contents, especially in acid-detergent lignin, withvalues of 22·6, 28·6 and 37·6g/kg DM in PER1, PER2 and PER3, respectively.Keywords: gas production, highlands, maize, stover, small farms.

Modeling methane emissions and methane inventories for cattle production systems in Mexico

Anaerobic 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 CO2. 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 CH4 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.

On-farm evaluation of the effect of coffee pulp supplementation on milk yield and dry matter intake of dairy cows grazing tropical grasses 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.

Development of Feeding Strategies for Cows in Small Scale Dairy Farming Systems in the Highlands of Central Mexico by a Simulation Model and On-Farm Experiments. Phase I: Development of a Novel Framework

The small scale dairy farming systems (SSDFS) contributes to maintain the rural environment and livelihoods in the highlands of central Mexico. However, their viability is compromised due to the high costs of feeds and deficient feeding strategies used by farmers. Simulation models in animal production are important tools for decision making, technology transfer and research. The aim of the present work was: develop a methodological framework for using a simulation model as a decision support tool to develop alternative feeding strategies for cows in SSDFS in the highlands of central Mexico. Local and alternative strategies were simulated (900 feeding strategies). The Buttercup model (BCM) predictions were compared with those reported in a previous work. Deficiencies in the local feeding strategies were identified in terms of metabolizable protein (MP). Alternative strategies were designed to cover these deficiencies by the use of concentrate supplementation. Three concentrates (C1= maize grain 610, soybean meal 310, urea 30, and cane molasses 50g kg−1 DM; C2= maize grain 630, soybean meal 320 and cane molasses 50g kg−1 DM; and C3= maize grain 900, urea 50 and cane molasses 50g kg−1 DM) where tested in order to meet the MP and metabolizable energy (ME) requirements and to evaluate the productive response of dairy cattle through on-farm experiments. For the BCM validation results data of milk yield from the on-farm experiments were compared with the BCM data predictions. The present methodology is aimed to simplify the use of simulation models in situations, places, and systems similar to the one reported here.

Development of Feeding Strategies for Cows in Small Scale Dairy Farming Systems in the Highlands of Central Mexico by a Simulation Model and On-Farm Experiments. Phase II: On-farm Experiments and Validation of a Simulation Model

The evaluation and validation of simulation models are important stages of model development. The aim of this work was to validate the Buttercup model (BCM) with experimental data from on-farm trials. Two on-farm experiments (Experiment 1 E1 and Experiment 2 E2) were carried out to evaluate the effect of supplementing dairy cattle with different sources of protein in Small Scale Dairy Farming Systems. Three concentrates (C1= maize grain 610, soybean meal 310, urea 30, and cane molasses 50g kg−1 DM; C2= maize grain 630, soybean meal 320 and cane molasses 50g kg−1 DM; and C3= maize grain 900, urea 50 and cane molasses 50g kg−1 DM) were developed using the BCM. The effect of the concentrates on milk yield, body condition score and live weight was evaluated using a double Latin Square experimental design. In E1 there were no significant differences (P> 0.05) for the variables evaluated. In E2, significant differences (P<0.05) were observed in milk fat content, for C2 (33.8g kg−1) was higher than C1 and C3 (26.2 and 26.0g kg−1). The results suggest that it was possible to fulfil the metabolisable protein requirements of the cows in these systems with low cost sources of non-protein nitrogen like the urea used in C3; and that the synthesis of microbial protein (from non-protein nitrogen and fermentable metabolisable energy of the concentrates) was enough to fulfil the cows’ requirements of MP for the milk yield levels observed in both experiments. The results also indicate that when specific input data set from the experiments was used the model predictions are acceptable, when comparing predicted vs. observed data as a very significant correlation was observed (P<0.01).

Participatory study on feeding strategies for working donkeys used by Campesino farmers in the highlands of central Mexico.

The aim of this work was to describe the feeding strategies for donkeys used by peasant farmers in central México. Feeding strategies for the dry and wet seasons are described, as well as the nutritional characteristics of the main forages and supplements used by the farmers. The extent to which the feeding practices used by farmers matched the digestible energy and crude protein requirements of donkeys for maintenance and work was determined. It was concluded that grazing on native grassland could provide enough energy and protein for donkeys at maintenance level and for those performing only a moderate amount of work. More research in required in order to have better estimates of intake and plant species preferred by donkeys under prevailing grazing conditions.

Impact of Extensive Grazing on Supporting and Regulating Ecosystem Services of Mountain Soils

Livestock grazing impacts the ecosystems of high mountains and adjacent low-elevation regions as a result of the physical, chemical, and hydrological connectivity of soil. In particular, grazing may alter the ecosystem services provided by soil, such as carbon and organic matter accumulation, carbon storage, and water infiltration. The present study evaluated the relative contents of soil organic matter (SOM) and soil organic carbon (SOC) on soil in a human-induced grassland and an frequently grazed Abies religiosa (Kunth) Schltdl. & Cham. forest in Nevado de Toluca, Mexico. It assessed carbon stocks in 2 different soil layers (0–5 cm and 5–25 cm), as well as soil compaction and water infiltration in both land uses. Results showed slightly lower SOM (21.7%) and SOC (12.6%) in soils on which livestock were grazed than in forest soils (25.7% for SOM and 14.65%, for SOC) at both depths and a greater bulk density of livestock soils (0.86 g cm−3) than of forest soils (0.73 g cm−3), particularly in the 0–5-cm layer (0.88 g cm−3) of livestock soils. More than 40 years of livestock grazing has clearly impacted the capacity of soils to accumulate organic matter and organic carbon. However, carbon stocks and water infiltration were not significantly affected, as low carbon accumulation was compensated by changes in soil bulk density. These results indicate that extensive livestock ranching and resource conservation are not necessarily mutually exclusive in the study site. Direct and indirect mechanisms involved in the provision of the evaluated regulating services should be further studied, taking into account the highly variable social and environmental conditions of Nevado de Toluca. Management policies should also aim to maintain an equilibrium between livestock rancher needs and conservation of supporting and regulating ecosystem services that are highly relevant to the functioning of mountain ecosystems.

Supplementation of dairy cows with commercial concentrate or ground maize grain under cut-and-carry or grazing of cultivated pastures in small-scale systems in the highlands of central Mexico

Small-scale dairy systems (SSDS) in Mexico represent over 78% of dairy farms and 37% of milk production. In the central highlands, many SSDS base the feeding of herds on irrigated cultivated pastures (mostly cut-and-carry), straws, and large amounts of commercial concentrates that result in high feeding costs and low economic sustainability. Intensive grazing may result in lower feeding costs when compared with cut-and-carry strategies. The high protein content of pasture may meet requirements of dairy cows with moderate milk yield (16–20 kg milk/cow.day), so that lower protein supplements, like ground maize grain, may substitute for commercial concentrates. An on-farm experiment following a participatory rural research approach was undertaken with seven farmers evaluating commercial concentrate (CC) or ground maize grain (MG) as supplement; and two pasture managements, grazing (G) or cut-and-carry (C) of irrigated ryegrass/white clover pastures to assess productive performance and feeding costs. Six farmers participated with four milking cows each and one farmer with two groups of four milking cows in a 2 by 2 factorial experiment. Daily milk yield per cow before the experiment was used as covariate. The experiment lasted 12 weeks. There is a trend in G for higher protein content in milk (P 0.05) in comparison with the grazing strategy. Supplementing with home-grown ground maize grain resulted in 28.5% higher margins per kg of milk produced. Implementing grazing involves less work burden for small-scale dairy farmers, and combined with home-grown grains as supplement is a viable option that may reduce feeding costs in these systems.

Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow−1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow−1 d−1 of oat silage, T3 = 3 kg DM cow−1 d−1 of oat silage, and T6 = 6 kg DM cow−1 d−1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow−1 d−1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.