Forage conservation and profitable smallholder milk production in Honduras

C Reiber, M Peters* and R Schultze-Kraft*

University of Hohenheim, Institute of Plant Production and Agroecology in the Tropics and Subtropics, University of Hohenheim,
Stuttgart, Germany
chreiber@gmx.de
* CIAT (International Center for Tropical Agriculture), Cali, Colombia

Abstract

In the seasonally dry tropics of  Honduras, common strategies to overcome dry-season feed constraints include supplementation with commercial concentrate and/or maize silage. However, these supplements are considered expensive by smallholders. The aim of this study was to evaluate (1) the effect of substituting part of supplemented commercial concentrate (CC) by farm-produced cowpea hay (CH, Experiment 1a) and cowpea grain concentrate (CGC, Experiment 1b), and (2) the effect of substituting maize silage (MS) by silage of the grass, Brachiaria brizantha cv. Toledo (TS, Experiment 2a), and of sorghum (SS, Experiment 2b) on milk yield and profitability measured as income over feed costs (IOFC) per cow and day. All experiments were carried out in collaboration with farmers and used change-over designs, involving balanced groups of crossbred cows.

Results of Experiment 1a revealed non-significant differences between treatments for milk yield and IOFC. However, the trend indicated that the slightly lower revenue in the CH treatment was more than compensated by its lower costs compared to the CC treatment. Results of Experiment 1b showed 0.58 kg/cow higher milk yield with CC treatment. However, IOFC was higher for CGC (1.47 $US) compared to CC treatment (1.26 $US).

Results of Experiment 2a revealed similar milk yield and IOFC for both treatments. However, the slightly lower milk yield with the TS treatment was more than compensated by lower feed costs compared to the MS treatment. Results of Experiment 2b showed significantly higher milk yield (11.32 kg/cow) and IOFC (2.17 $US) of SS compared to MS treatment (8.76 kg/cow; 1.54 $US).

Farm-produced conserved forages such as CH and CGC as well as TS and, particularly, SS proved efficient as (partial) substitutes for CC and MS, respectively, and should be further promoted as low-cost and high-quality conserved forage options for smallholders.

Key words: Cowpea grain concentrate, cowpea hay, grass silage, income over feed costs, participatory on-farm feeding trials

Introduction

Feed shortage during the five to six months of dry season in many areas of Honduras severely limits livestock production, farm productivity and smallholder income (Lentes et al 2010a). Common strategies to overcome feed constraints and maintain milk production during the dry season include supplementation with high levels of commercial concentrate (Lentes et al 2010b) and/or feeding of maize silage (Reiber et al 2010). These strategies, however, are considered expensive by smallholders. The use of alternative conserved forage from legumes and grasses promises higher returns per litre of milk (Holmann and Lascano 2004, Nakiganda et al 2005) but is rarely applied by smallholders in the tropics (Shelton et al 2005, Mannetje ‘t 2000).

The conservation of adapted forage legumes such as cowpea (Vigna unguiculata) and grasses such as Brachiaria brizantha cv. Toledo and sorghum have been promoted in Honduras during farmer trainings and field days in the framework of a research project carried out by CIAT (Centro Internacional de Agricultura Tropical) in collaboration with national partners and the University of Hohenheim. Therein, on-farm experiments were conducted in collaboration with farmers in order to evaluate the potential of conserved-forage options under smallholder conditions.

The objective of this study was to evaluate the effect of (1) partially substituting commercial concentrate by cowpea (Vigna unguiculata) hay (Experiment 1a) and cowpea grain concentrate (Experiment 1b), and (2) substituting maize silage by B. brizantha cv. Toledo silage (Experiment 2a) and sorghum silage (Experiment 2b) on milk yield, body weight (BW) change, revenue and profitability measured as income over feed costs (IOFC). IOFC is a proven financial measurement to monitor the profitability of a dairy operation (Penn State University 2009).

Materials and Methods

Location

The experiments were conducted on four farms in Victoria and Sulaco, department of Yoro, Honduras, during February-April in the 2006 dry season. The farms are located at altitudes of about 400 m a.s.l. Average temperature ranges from about 22 °C in the coldest month January to about 27 °C in the hottest months April and May. Average annual precipitation ranges from about 1000 mm in Sulaco to 1150 mm in Victoria. The dry season usually begins in November and lasts up to 6 months.

Production of silage and hay

Fresh matter production of cowpea (variety IITA 284/2) was approximately 18 tons/ha. An area of 3600 m² of cowpea was cut for hay in the early flowering stage (mid November). The first day, it was sun-dried. The second day, for further drying and in order to prevent leaf losses in the field, it was hung underneath a roof with open sides. About 1.2 tons of cowpea hay was harvested of which about 0.46 tons were used for the experiment.

The pasture grass Toledo was fertilized with 65 kg of urea (46% nitrogen) per ha. About 5 tons of Toledo from an area of about 3500 m² were cut in December after 32 days of re-growth. After one day of dehydration in the field and chopping to a particle size of 8 to 10 cm, it was ensiled in a pit silo. About 10% of chopped forage sugarcane was added in layers as additive to support the fermentation process with water-soluble carbohydrates.

Maize (local commercial variety) and sorghum (Christiani, HF 802 hybrid) were cut for silage at milky to doughy stage of maturity and ensiled in a bunker and heap silo, respectively. No additives were used. 

Selection of cows

Criteria for the selection of the cows were a lactation period of more than two months at the time of the experiment, similar milk yield, weaned calves, number of calvings between two and six, and similar BW and body condition scores (BCS) according to Elanco Animal Health (1997) (Table 1). Cows represented regionally common crossbred animals with a Bos taurus share of 25% to 62.5%.

Experimental designs

The experiments were conducted using change-over (reversal) designs of switch-back and rotational (Latin square) types (Lucas 1960) (Table 2). A feeding period consisted of an adaptation phase of 3-7 days and the subsequent measurement phase of seven days.

Data collection

Depending on the farm and the number of milkings, milk yield for each cow was recorded once or twice daily using a digital scale. For Experiments 1a and 2a, BW was measured every seven days, at the beginning and at the end of each measurement period using a portable digital livestock balance. BW measurements were always done at the same time of the day (immediately after morning milking) to avoid BW changes due to differences in the degree of rumen and udder fill.

Costs of supplemented feed components were enquired using a structured questionnaire. In the experiments where cows had also access to grass pastures for grazing, the costs of the grazed pastures were not considered.

Feed rations and treatments

Experiment 1a:

The farmer decided upon the feed rations. The feed was supplemented in two rations, one in the morning and one in the afternoon during milking. Cows did not graze during the experiment. The basic feed ration (BFR) was maintained during the whole experiment and was the same for all cows, consisting of 9.1 kg maize silage (35.3% dry matter, DM) + 13.6 kg sugarcane (25% DM) + 6.8 kg maize straw (90% DM).

Based on the farmer’s suggestion to substitute part of the commercial concentrate (CC) (1.8 kg; 22% crude protein, CP) by a protein equivalent amount of cowpea hay (2.73 kg; 16.2% CP), the following treatments were applied:

Treatment CH (cowpea hay): BFR + 3.64 kg CC + 2.73 kg CH

Treatment CC (commercial concentrate): BFR + 5.45 kg CC

Experiment 1b:

Basic feed ration (BFR): 12.3 kg silage (mix of 85% sorghum, 7.5% maize and 7.5% cowpea foliage) + grazed pasture (Brachiaria brizantha cv. Toledo)

Treatment CGC (cowpea grain concentrate): BFR + 1.4 kg CC (“Maintenance”, min 12% CP) + 1.4 kg ground maize + 1.4 kg ground cowpea grain

Treatment CC (commercial concentrate): BFR + 4.1 kg CC (“Lechera Nutricia”, min 20% CP)

Experiment 2a:

The cows were fed on a time-restricted ration of maize silage (MS) and Toledo silage (TS) from 9 am to 2 pm. Thereafter, cows grazed on Andropogon gayanus and Brachiaria hybrid cv. Mulato pastures. During the first days of the initial adaptation phase, the quantity of silage offered was adjusted to ensure maximum intake and then maintained throughout the experiment.

BFR: 2.6 kg CC (min 20% CP) + pasture

Treatment MS: 13.6 kg fresh matter (FM) of maize silage

Treatment TS: 12.5 kg FM of Toledo silage

Experiment 2b:

Sorghum silage (SS) and maize silage (MS) were offered in the morning from 5.00 to 11.30 am and in the afternoon from 3.00 to 4.30 pm (time restricted supplementation).

BFR: 2 kg CC (min 20% CP) + pasture (B. brizantha cv. Toledo) grazing

Treatment SS: Sorghum silage (ad libitum)

Treatment MS: Maize silage (ad libitum)

Analysis of forage quality

Silage samples were taken along in a cooler for laboratory analyses of pH, CP, neutral detergent fibre (FDN), ether extract and ash. Analyses were done following standard procedures according to the Association of Official Analytical Chemists methodologies (AOAC 1990). Additionally, silage fermentation quality was assessed by evaluation of smell, colour and texture according to ÖAG (1999).

Statistical analyses 

For statistical analysis of milk yield, revenue and IOFC, only data from the measurement phase were considered. IOFC was calculated by subtracting total feed costs from revenue from milk sales, according to the following formula: IOFC ($US/cow/day) = milk price ($US/litre) x milk yield (kg/cow/day) – total feed costs ($US/cow/day), using a dry season milk price of 0.29 $US/litre and considering one litre of milk as one kg and vice versa. Thus IOFC is a linear transformation within a treatment.  

Data were processed using IBM SPSS Statistics 19 Software (2010). The data were subjected to analysis of linear mixed model procedures based on the following equation adapted from Tempelman (2004):
 

Y_ijkl = μ + α_i + β_j + c_k + g_l + (αβ)_ij + (αc)_ik + e_ijk

Where;   Y_{ij k}  =  Dependent variable (milk yield, revenue, IOFC and weight change)

                 μ    =  Overall mean

                 α_i   =  Effect of _ith treatment

                 β_j     =  Effect of _jth feeding period

                 c_k   =  Effect of _kth cow 

               (αβ)_ij = Effect of _ith treatment * _jth feeding period interaction

               (αc)_ik = Effect of _ith treatment * _kth cow

                e_ijk    =  Error effect

The factors treatment and feeding period including their interaction treatment * feeding period were treated as fixed effects whereas cow and its interaction cow * treatment were treated as random effects. It was assumed that repeated measurements for milk yield within a period were correlated, but observations of different cows were assumed to be uncorrelated. A model assuming that residuals had an autoregressive variance-covariance structure with one factor (AR1) was found to fit well to the data. Additionally, effects of treatments were tested for significance using the F-test. In the case of only two stages of a factor, the result is identical to that of a t-test, by which differences between least square means (LSM) are tested.

For the analysis of Experiment 1b, the random effect treatment * cow was excluded from the model according to analysis of replicated Latin square designs as shown by Tempelman (2004). For the analysis of Experiment 2b, the effect of the treatment * feeding period interaction was confounded with the period effect and therefore dropped from the model. The remaining period effect includes both the period effect and its interaction effect with treatment.

Results

Experiment 1a: Partial substitution of commercial concentrate (CC) by cowpea hay (CH)

Feed intake and quality

Cows consumed 100% of the offered BFR (Table 3). Cowpea hay had a CP content of 16.2%, the commercial concentrate a CP of 22% (data not shown). On average, daily DM intake was 3.5% of BW.

Feed costs

The costs for the feed components of the basic feed ration (BFR) totalled 0.31 $US/cow. The total feed ration (TFR) costs were 1.43 and 1.78 $US/cow for treatments CH and CC, respectively (Table 4).

BW change, milk yield, revenue and IOFC

According to the overall weight averages of both groups, cows lost weight during the concentrate treatment whereas they gained weight during the cowpea hay treatment (Table 5). The difference between the treatments, however, was not significant. The trend of results showed a slightly lower milk yield but a higher IOFC with the CH treatment compared to the CC treatment (P > 0.05).

Experiment 1b: Partial substitution of commercial concentrate by cowpea grain concentrate

Feed quality and intake

The farm-produced cowpea grain concentrate (CGC) was composed of 33% CC (“Maintenance”, 13.8% CP), 33% ground maize (10.3% CP) and 33% ground cowpea (26.0% CP) averaging 16.7% CP. The concentrate was readily accepted by the cows. The concentrate of treatment CC (“Lechera Nutricia”) had a CP content of 22.5%.

Dry matter intake (DMI) of the different feed components averaged 3.7 kg for the silage mixture (as part of BFR), an estimate of 1.4 kg of pasture grass (as part of BFR) and 3.6 kg for both concentrate treatments with a total of about 8.7 kg DM/cow/day (on average 2.5% of BW).

Feed costs

Table 6 shows the costs of the feed ingredients. The total feed costs per ration were 0.38 $US/cow higher for the CC treatment than for CGC. Feed costs per kg of milk were 0.10 and 0.14 $US for CGC and CC treatment, respectively.

Milk yield, revenue and IOFC

Milk yield difference between CC and CGC was significant, with 0.58 kg/cow in favour of the CC treatment (Table 7). IOFC was in the CGC treatment 0.21 $US/cow higher than in the CC treatment. This means that the lower milk yield in the CGC treatment was more than compensated by lower costs.

Experiment 2a: Effect of substituting maize silage by Brachiaria brizantha cv. Toledo silage

Silage quality and intake

The pH value in combination with DM content indicated that Toledo grass did not ferment well (Table 8). However, this could not be confirmed through organoleptic evaluation. Both silages had a pleasant sweet odour and green colour (organoleptic mark 1 = very good).

The cows consumed all maize silage offered (13.6 kg of FM per day, equivalent to 4.2 kg/cow/day of DM). On average, 1.4 kg FM/cow/day of the offered Toledo silage was rejected. Thus, its intake turned out to be 11.1 kg FM/cow/day or 2.8 kg DM per cow. Average intake of commercial concentrate (22% CP) was 2.6 kg/cow in both treatments.

Feed costs

Feed costs/cow totalled 0.90 $US and 0.81 $US for the MS and TS treatments, respectively (Table 9).

BW change, milk yield, revenue and IOFC

Average daily BW change difference between treatments was not significant. Average body condition scores increased during the experiment from 3.79 to 4.04 and did not show any difference between treatments, thus indicating a positive energy balance of the rations. Results revealed similar milk yields of cows when supplemented with maize silage (MS) and Toledo silage (TS) (Table 10). IOFC was slightly higher for TS than for MS. This means that the lower milk yield (and lower revenue from milk sale) of TS was more than compensated by its lower cost. 

Experiment 2b: Effect of substituting maize silage by sorghum silage

Silage quality and intake

The pH values in combination with DM contents indicated that both silages had fermented well (Table 11). This was confirmed by organoleptic evaluations of smell (pleasantly sweet, absence of butyric or strong acid smell), colour (green) and texture (intact) with an overall grade of “very good” for both silages.

Cows preferred sorghum silage (SS) to maize silage (MS), which was corroborated by a considerably higher intake: Intake of MS averaged 18.2 kg FM (5.6 kg DM) whereas that of SS averaged 22.8 kg FM (8.0 kg DM).

Feed costs

Table 12 shows the costs for MS and SS production. Sorghum fresh matter (FM) production was estimated at 17.1 tons/ha. Considering a 5% loss due to silage spoilage, the production costs of SS were about 0.029 $US/kg of FM. Maize FM production was estimated at 28.6 tons/ha. Considering a 5% loss due to silage spoilage, the production costs of MS were about 0.025 $US/kg of FM.

Two sorghum silage cases were considered for the calculation of IOFC: (a) SS costs of 0.029 $US/kg (only considering the first cut), and (b) the same costs for MS and SS (0.025 $US/kg). Case (b) serves to demonstrate how the higher palatability (or intake) of SS influences profitability. Total feed costs of the SS treatment were for cases (a) and (b) 1.09 $US/cow and 0.97 $US/cow, respectively, and 0.89 $US/cow for the MS treatment (Table 13). Feed costs per kg of milk were 0.096 and 0.101 $US for SS and MS treatment, respectively.

BW change, milk yield, revenue and IOFC

On average, cows maintained their BW during the period, when MS was supplemented, at 406 kg/cow. In the SS treatment, average BW slightly increased to 413 kg/cow. Average milk yield and revenue were significantly higher from SS than from MS, with a difference of 2.56 kg/cow and 0.74 $US/cow, respectively (Table 14). IOFC was 0.54 $US/cow and 0.63 $US/cow higher in treatment SS than in treatment MS, for scenarios (a) and (b), respectively. Results indicate that the higher feed costs of SS were more than compensated by higher milk yield.

Discussion

Cowpea hay and cowpea grain concentrate versus commercial concentrate

Both experiments indicated that feed costs could significantly be reduced by substituting commercial concentrate by farm-produced feed such as conserved cowpea products while maintaing the performance of the cows. Based on the results of this study, a farmer with 10 cows could save a total of about 200 $US (Experiment 1a) and 250 $US (Experiment 1b) during a supplementation period of four dry-season months when partially substituting commercial concentrate by farm-produced cowpea hay and cowpea grain concentrate, respectively.

The CP content of cowpea hay (16.2%) in this study was lower than the range of 19.5-26% CP found by Ravhuhali et al (2010) and higher than 10% and 15.4% CP found by Savadogo et al (2000) and Baloyi et al (2001), respectively. The CP content of cowpea grain (26.0%) was as high as that reported by Rivas-Vega et al (2006) (26.1%). A number of studies have confirmed a positive effect of cowpea products on ruminant performance (Anele et al 2010, Akinlade et al 2005, Bartholomew et al 2003, Chakeredza et al 2002, Koralagama et al 2008, Murthy and Prasad 2002).

Similar to the results of this study, Kiyothong and Wanapat (2003) found no change in milk yields of crossbred dairy cows when 33% of the concentrate supplement was replaced by hay made from cassava foliage and the forage legume Stylosanthes guianensis CIAT 184. From an intensive grazing system with ad libitum access to high-quality pastures in California, USA, Daley et al (2010) reported no significant milk yield difference but higher IOFC per cow when reducing the concentrate supplementation levels from 24% (5.4 kg) to 12% (2.7 kg) of dry matter intake. McEvoy et al (2008) found no significantly lower milk production of spring-calving Holstein-Friesian cows in early lactation when reducing concentrate from 6 kg to 3 kg per cow per day as long as animals had access to a high-quality pasture. Vera (1990) investigated the effect of 50% substitution of commercial concentrate by soybean hay in growing heifers and reported a saving of 365 kg of concentrate, equivalent to about 100 $US/cow per year.

Supplementing cows feeding on tropical pasture grasses with protein is crucial to support animal performance, even during the rainy season due to limited levels of metabolizable protein in tropical grasses. This is particularly valid for the dry season when, in general, only poor-quality forages with low CP content and low digestibility are available. Juarez Lagunes et al (1999) evaluated the carbohydrate and protein fractions and corresponding rate of digestion of 15 tropical pasture grasses in Mexico using the Cornell Net Carbohydrate and Protein System to evaluate their ability to support milk production of dual-purpose cows. They showed that milk production increased by about 35% as CP increased from 8 to 12%.

The problem of oversupplementation with concentrates and underutilization of inexpensive forage resources was highlighted by Baars (1998) in Costa Rica and Lentes et al (2010b) in Honduras. The challenge is to reduce the expensive dependence on commercial concentrates by an appropriate use of conserved forage including legumes. As shown in this study, substituting commercial concentrate by farm-produced cowpea products can reduce feed costs and have a direct and significant effect on farmers’ income even though milk yields might be slightly lower. Khalili et al (1992) found that the milk yield of crossbred cows increased by 0.52 kg per cow and day per kg additional concentrate supplemented. Based on concentrate costs (0.17-0.27 $US/kg, depending on quality) and milk prices (0.29 $US/kg) in Honduras at the time of this study, milk yield increase should be at least 0.59-0.93 kg per kg additional concentrate to achieve an increase of IOFC.

Moreover, on-farm produced protein sources such as cowpea hay and grain are likely to have lower price fluctuations and be less dependent on international markets than concentrates based on imported ingredients. Costs of commercial feed concentrates are expected to increase even further, partly as a result of the increased demand for land and agricultural products, particularly maize, for biofuel production (FAO 2009).

Therefore, it is important to offer farmers alternatives such as forage legumes to be integrated in their production systems in order to remain competitive. Cowpea can be intercropped in maize and sorghum, or produced at the end of the rainy season, filling a niche that could contribute to additional food, feed and/or income generation of smallholders. The level to which protein sources should be supplemented needs to be adapted to the prevalent situation considering nutrient requirements of the cow throughout and between lactation periods, nutrient availability from grazed forages throughout the year, and the cost of supplements.

Brachiaria brizantha cv. Toledo silage and sorghum silage versus maize silage

Based on the results of this study, a farmer with 10 cows would save about 60 $US (Experiment 2a) and 648 $US (Experiment 2b) during a supplementation period of four dry-season months when substituting maize silage by Toledo silage and sorghum silage, respectively.

The Toledo silage in this study presented 25.6% DM and pH 5. According to Weissbach (2002), a pH £ 4.35 is required to permit favourable conditions for a stable silage whereas the risk of butyric acid fermentation increases in the case of grass silages with pH > 4.35. Though the risk of mal-fermentation with clostridia might have been high with the Toledo silage used in Experiment 2a, organoleptic evaluation indicated absence of butyric and strong acetic acid odour. One reason for the inhibition of butyric acid formation by clostridia could have been that Toledo was fertilized with nitrogen. The degradation product of nitrate, nitrite, is an inhibitor for the development of clostridia (Spoelstra 1985). Another reason could have been that due to the relatively long particle size of the chopped material and the rather coarse texture of Toledo grass, moisture was bound intracellularly and therefore had less influence on the fermentation process. Reiber et al (2009) showed that short wilting and the addition of sugar-containing additives, especially molasses, improved fermentation quality of B. brizantha cv. Toledo bag silage.

O’Mara et al (1998) examined the effects of replacing highly digestible grass silage by maize silage, on forage intake and milk production of Friesian cows. A proportion of one third maize silage (two thirds grass silage) was sufficient to achieve maximum milk yield. Kirchgessner et al (1981) found significantly higher milk production when grass silage and maize silage were mixed instead of feeding grass silage in the morning and maize silage in the evening. Keady et al (2008) showed that including maize silage in grass silage-based diets can improve milk output due to increased metabolizable energy intake. They calculated the potential concentrate-sparing effect to be as high as 3.4 kg/cow per day when maize silage is included in a 40% proportion as forage component of grass silage-based diets.

Results of Experiment 2b confirmed farmer’s previous observation that cows produced considerably more milk with sorghum silage than with maize silage. However, the reason why cows preferred sorghum silage to maize silage remains unclear since both silages were of similar quality.

The costs of sorghum silage per kilogram was slightly higher compared to maize silage mainly due to lower biomass production (17.1 tons FM/ha compared to 28.6 tons/ha). Sorghum biomass production in other nearby fields was 28-36 tons/ha whereas, under favourable conditions, total biomass production per year can exceed 100 tons. In this case, biomass production of sorghum was very low. Reasons include: a) sorghum had low plant density (50,000 plants/ha); b) whereas maize was fertilized with about 130 kg/ha NPK (18-46-0) and the same amount of urea, sorghum was fertilized only with about 130 kg/ha NPK; and c) water availability was different since sorghum was sown after maize in October (towards the end of the rainy season). Therefore, data of biomass production of sorghum and maize used in this case can not be directly compared and taken for further cost-benefit analyses.

The calculation of sorghum silage costs did not consider that sorghum re-sprouts and can be harvested another two times. Silage from the second (and third) cut is less expensive since land preparation and establishment costs are not included in its calculation. Assuming for the second cut a similar production of about 17 tons FM/ha, sorghum silage cost would be about 0.015 $US/kg FM, which is almost half of the cost of the first cut and lower than the cost of maize silage (0.025 $US/kg FM).

Many farmers in the region argued that they favoured sorghum silage rather than maize silage for the following reasons: a) sorghum can be harvested several times without need of re-cultivation, thus reducing production costs; b) after cutting sorghum, it re-sprouts rapidly whereas maize has to be replanted causing a delay in forage production; and c) sorghum, due to higher drought tolerance or (in case of re-growth) its already developed root system, produces biomass even well into the dry season, when maize does not grow any more. As an alternative strategy, sorghum could be harvested two to three times for silage, and the last cut could be supplemented fresh or as hay in the dry season. As a consequence of farmers’ observations, maize was being substituted by sorghum for silage in the Yoro region.

Conclusions and Recommendation

• Farm-produced cowpea hay and cowpea grain concentrate proved efficient as partial substitute of commercial concentrate due to their lower costs.
  
  
• Brachiaria brizantha cv. Toledo silage and, more so, sorghum silage proved efficient as substitute of maize silage.  
  
  
• Further on-farm studies are necessary to investigate the potential of different grass and legume hay and silages that are being adopted by smallholders. 
  
  
• Extension service should support farmers with respect to optimizing their feeding management, i.e., identifying the most efficient dry-season feed rations considering nutrient requirements of cows, forage availability, in terms of quantity and quality, and feed costs.

Acknowledgements

The authors gratefully acknowledge the financial support for this work by BMZ/GTZ (now GIZ, Gesellschaft für Internationale Zusammenarbeit). Special thanks go to the collaborating farmers Heraldo Cruz (Experiment 1a), Isidoro Murillo (Experiment 1b), Edwin Torres (Experiment 2a) and Teofilo Flores (Experiment 2b). Thanks to the Honduran Institute for Agricultural Research and Extension (Direccción de Ciencia y Tecnología Agropecuaria, DICTA) for the collaboration and provision of office facilities. We are grateful to Peter Lentes and Volker Hoffmann for their continuous support. Sincere thanks to Jens Möhring for his valuable statistical consulting service.

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Received 16 April 2011; Accepted 4 July 2011; Published 3 August 2011

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