Effect of the physiological state of Criollo goats on the botanical composition of their diet in NE Mendoza, Argentina

ALLEGRETTI, L.; PAEZ LAMA, S.; SARTOR, C.; EGEA, V.; FUCILI, M.; PASSERA, C.

JOURNAL OF SMALL RUMINANT RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 103 p. 152 - 157

0921-4488

The botanical composition of the diet and species preference of grazing goats in differentphysiological states were evaluated in the autumn and winter seasons. The study wasperformed in a desert rangeland in the northeast (NE) Mendoza region in Argentina. Foodavailability was estimated from forage species cover. Rectal grab faecal samples were collectedfrom goats, and the botanical composition of the goat diet was determined using amicrohistological technique. Goat preferences for each species consumed were calculatedbased on Ivlev’s index. Nutritional composition and secondary compounds of forage specieswere determined. Correlations between diet and availability; and between goat preferenceand nutritional composition of forage species were also estimated. The habitat consisted ofa dominant woody stratum associated with an herb stratum primarily composed of grasses.Goats in different physiological states utilised a significantly higher proportion of woodyvegetation compared to grass (p < 0.01). When grass availability was high (autumn), the herbstratum was more utilised by pregnant and lactating goats than by dry goats (p < 0.05). Inthe winter, the diet of lactating goats consisted of more Atriplex lampa compared to the dietof dry goats (p < 0.05), probably due to the high crude protein content of the plant. Goatsconsumed forage species with highly variable total phenol and tannin contents, which didnot negatively affect selection. Correlations between diet and availability were high in thewinter for dry (rs = 0.88, p < 0.02), pregnant (rs = 0.93, p < 0.01) and lactating goats (rs = 0.97,p < 0.01) but were not significant in the autumn. A significant correlation between preferenceand crude protein was shown during the autumn season for pregnant and lactatinggoats (rs = 0.6, p < 0.05). Forage availability was the main factor influencing diet selectionin this arid environment. When food availability was not a limiting factor, goats selecteda diet that most closely matched their nutritional requirements. Physiological state modifiednutrient requirements and affected diet selection in that pregnant and lactating goatsselected forage species with high protein contents.