Dietary selection by goats and the implications for range management in the Chihuahuan Desert: a review

Abstract

Field studies characterising the forage resources of mixed-breed goats on Chihuahuan Desert rangelands were reviewed and the principal sources of variation in their diet choices discussed. Goats eat a varied diet comprising at least 126 plant species in this landscape. Goats are highly selective feeders, changing their diet from predominantly forbs (8–64%) to browse (35–88%). Graminoids make up only ~5% of the diet, but grasses could be important dietary components on rangelands in good condition. Feed intakes range between 0.8% and 3.4% of bodyweight, depending on the season. DM digestibility of forage selected by goats ranges between 44% and 65%. Annual crude protein (CP) in forages selected by goats varies from 80 to 160 g CP kg–1 DM. Overall, pregnant and lactating goats manage to ingest food that contains higher amounts of CP and lower amounts of cell wall than non-pregnant, non-lactating goats. Goats not adapted to severe shortage of forage select a diet that does not match their nutritional requirements and fetal losses occur. Goat kids select higher quality diets than do mature goats (94.5 vs 88.5 g CP kg–1 DM). Granadina goats eat ~20% more shrubs, including 3-fold more Larrea tridentata (DC) Cav., than Nubian goats. Goats with severely eroded incisors avoid grasses, focusing on tender-leaved shrubs. During the rainy season, bucks select mainly shrubs (78% of the diet) and avoid grasses (1.7% of the diet), whereas does rely heavily on forbs (about one-third of their diet). Alternating use of grazing grounds increases shrub ingestion by 25%. No evidence exists indicating that food choice by goats in this arid environment is biased towards forages with lower secondary compounds. It is concluded that the flexible, broad-scale and opportunistic feeding behaviour of goats make them an effective animal to sustainably exploit the forage resources of the Chihuahuan Desert.

Diet selection and n-3 polyunsaturated fatty acid deposition in lambs as affected by restricted time at pasture

“…39.4%, on average). The similar effects of higher selectivity in diet were observed in young goats 15 , 19 . It could be concluded that young animals show a partial preference for palatable forages in most circumstances, but they were remarkably adept at selecting highly nutritious forage when time to access pasture is limited on resource-available grasslands.…”

“…A selectivity index was also calculated, defined as the proportion of a plant type in the diet relative to its proportion in the pasture period. This was quantified by calculating selectivity indices (D) for each feed item using Jacobs’ 19 , 33 selectivity index (D varied from 0 to 1 for positive selection and from 0 to −1 for negative selection). We chose Jacobs’ index as it is independent of the relative feed abundance, and directly reflects sheep selection and the impact on a given feed item in the environment.…”

Vaina de mezquite (Prosopis spp.) alimento para el ganado caprino en el semidesierto

“…promete ser un recurso alternativo de alimentación que puede ser utilizado por las industrias de procesamiento de alimentos para el ganado. La utilidad de las vainas en la alimentación del ganado ha sido reportada anteriormente (Sawal et al, 2004;Mahgoub et al, 2005;Awawdeh, 2011;Mellado, 2016). La composición química (Cuadro 1) de las vainas de Prosopis spp.…”

“…Los resultados del contenido de cenizas fueron mayores (p> 0.05) en vainas maduras, lo cual es similar al valor de 4.5% reportado por King`ori et al 2011 Sin embargo esta variación entre los datos de la literatura podría deberse a la edad de las vainas al momento de la cosecha, el tipo y la fertilidad del suelo, así como al sistema agroecológico bajo el cual se cultivaron los árboles. Según varios autores la especie o variedad vegetal, el suelo, el clima, el pastoreo, la fracción vegetal y la etapa de madurez al momento del muestreo afectan el valor nutritivo de los forrajes (Baumont et al, 2000;Sawal et al, 2004;Bhatta et al, 2007;Mellado, 2016 Aunque los resultados de la literatura atribuyen este valor energético a su contenido de carbohidratos principalmente azúcares no reductores (Del Valle et al, 1983;Sawal et al, 2004;González et al, 2008;Ríos-Saucedo et al, 2012). De acuerdo con Sawal et al (2004); Baraza et al (2008) las vainas maduras son apetecibles debido a su alto contenido energético (75% y 82.2% de TND, respectivamente), esto es contrario a los resultados obtenidos.…”

Pre-Columbian Rock Mulching as a Strategy for Modern Agave Cultivation in Arid Marginal Lands

“…As indicated above, out of all the organs of agaves, the stem head produces the most edible biomass (Nobel, 2003). Inflorescences, leaves, and stalks can also be used for food and to feed cattle (Bos primigenius taurus), sheep (Ovis aries), and goats (Capra aegagrus hircus) (Gentry, 1972;Pinos-Rodríguez et al, 2006, 2008Hartung, 2016;Mellado, 2016). Gentry (1972) indicated that inflorescences of some Agave species are edible.…”