The agronomic performance and nutritive value of twelve annual and perennial grasses and legumes were analysed in order to define alternatives to local forages for dry-season feeding of ruminants in the Peruvian Andes. There were twelve species and two fertilizer treatments (no fertilizer and a N;P;K fertilizer mainly applied at sowing) in an experiment with a randomized complete block design with three replicates at each of two sites. Plant height, soil cover by forage and weed species, frost damage, dry matter (DM) yield and nutritive value of herbage were evaluated in 2005 and 2006. Among the annual species, Hordeum vulgare L. cv. UNA 80 and xTriticosecale Wittm. had the highest DM yields when fertilized (8226 and 6934 kg ha(-1) respectively). Without fertilizer the alternative cultivars had similar DM yields to that of the local forages. Cultivars of Avena sativa L. had lower concentrations of neutral-detergent fibre (NDF) (557 g kg(-1) DM) and higher concentrations of predicted net energy for lactation (5.86 MJ kg(-1) DM) than the other annual grass species (625 g kg(-1) DM and 5.01 MJ kg(-1) DM respectively), while the legumes were superior in concentrations of crude protein (277 g kg(-1) DM) and NDF (362 g kg(-1) DM). Considering the low agronomic performance of the perennial forages, a mixture of fertilized annual grasses and legumes appears the most appropriate approach to meeting the demand for forage of high nutritive value in the Peruvian highlands.

Twelve Brown Swiss (BS) and 12 Peruvian Criollo cows (CR, a local Peruvian cow type adapted to altitude and harsh environment), both Bos taurus and adapted to altitudes >3500 m a.s.l. (above sea level), were kept at 200 and 3600 m a.s.l. and assigned to three dietary treatments, respectively. The experimental design was a 2 (cow types) x 3 (diets) x 2 (sites) factorial arrangement (total n = 72). The diets used represented the quality of typical highland dry-season forage (DS), highland rainy-season forage (RS) and a diet with optimized nutrient composition (OC). Contents (g/kg dry matter) of crude protein clearly increased from diet DS to RS and OC (from 42 to 81 and 131) and neutral detergent fiber contents decreased with increasing diet quality (from 734 to 580 and 512 for DS, RS and OC, respectively). The CR consumed less dry matter than the BS (P<0.001) (g/day and kg BW0.75; 65 and 68,117 and 136, 130 and 158, for CR and BS receiving diets DS, RS and OC, respectively). Both, dry matter intake and energy-corrected milk (ECM) yield increased with diet quality (P<0.05); the latter nearly doubled for both cow types when switching from diet DS to OC. A similar increase was found for daily ECM yield expressed in g/kg BW0.75 (34 and 46, 57 and 76, 63 and 91, for CR and BS fed diets DS, RS and OC. respectively). Especially in CR the major part of this increase was already found when replacing DS by RS (cow type x diet interaction, P<0.001), indicating that CR cows had approached their genetic production limit with diet OC. The low intake with diet DS resulted in an energy deficit characterized by a massive mobilization of body reserves in both cow types. In intake, performance and metabolic traits there were no clear indications that the CR cows tolerated the low-quality diet better than the BS cows. Both cow types also showed similar performances at the two sites, and high altitude did not seem to cause any extra maintenance energy requirements but was found to increase milk fat content (P<0.05). These results lead to the conclusion that the metabolic responses to under-nutrition and hypoxia were similar for the two cow types. (C) 2008 Elsevier B.V. All rights reserved.

In four communities in the Peruvian Andes, 56 farmers were interviewed every three months over a period of one year. Information linked to milk and cattle production such as activities, inputs (labour, means of production, capital) and outputs (milk, cheese, animals) were recorded using a closed-ended questionnaire. The communities were divided into two groups with low (LC) and high (HC) level of dependence on income from milk and animal sales. The survey results showed that cattle production on the LC farms was based on less land and a smaller herd (3.32ha/farm, 1.06 lactating cows) than on HC farms (10.28ha/farm, 4.19 lactating cows). The data from the survey and the results of the nutritional analyses of 74 feed samples were introduced into a model that applied linear programming techniques in order to estimate the farm household income under the current production systems and evaluate the economic impact of improved forage varieties for hay production. Furthermore, the economic viability of other changes in fodder and herd management was tested. Both groups were characterised by a dual-purpose system generating a gross income from the sale of both, milk and live animals in the amount of -21 (LC) and +1057 US$/farm and year (HC). Due to higher production costs for forages and better access to markets, LC communities were characterised by an integrated crop–livestock system whereas in the HC group income was mainly based on livestock. Introduction of improved and fertilized barley for hay production, was estimated to increase the annual farm income to 127 and 1257 US$ for LC and HC, respectively. This increase was accompanied by an increment of the animal number. Maintaining the animal number but increasing the milk production/cow by feeding additional forage was a less profitable option generating 50 and 1221 US$ of income per farm and year for LC and HC, respectively. The production of hay was limited by high costs (external labour) in LC communities and the restricted availability of family labour in the HC group. A scenario based on the use of improved cow genotypes led to the highest estimated annual farm income for HC communities (1280 US$) but was less favourable for LC. The modelling results showed that the best development strategy depends on various factors such as production costs, access to the markets and to irrigation and availability of different feed resources.