Foraging behaviour and diet selection of free-ranging sheep and goats in the Negev Desert, Israel

Abstract

The foraging behaviour and dietary selection of free-ranging Awassi sheep and Negev goats when shepherded in the Negev Desert was determined. Measurements were made for 9 weeks (W1-W9) from the beginning of February, following winter rains and emergence of annual plants, to the end of March, after the herbaceous vegetation dried up. Since sheep are grazers and goats are intermediate feeders, it was predicted that goats would browse more and consume proportionately more browse than sheep. These predictions were only partially supported. In fact, the foraging pattern was similar between sheep and goats (Mantel test, P < 0·05) until W8 and only towards the end, at W9, did patterns differ significantly (Mantel test, P = 0·214) between these two ruminants. There was no difference (P = 0·575) between sheep and goats in foraging; however, a period effect was found (P < 0·001). In February (W2), sheep and goats grazed 0·69 and 0·71 of the time allotted for foraging and neither species browsed. Browsing commenced only at the beginning of March (W4), when goats browsed 0·08 of the time and sheep 0·07 of the allotted time for foraging. The proportion of time spent browsing increased at the end of March (W9) when annuals disappeared, but the total time spent foraging decreased: goats browsed 0·29 and grazed 0·25, while sheep browsed 0·19 and grazed 0·26 of the time allotted for foraging. Goats increased the proportion of browse consumed gradually throughout the season, whereas sheep maintained a relatively higher proportion of herbaceous plants and only in late March (W8), at which time very little herbaceous plants were available, shifted abruptly to consume mainly browse. In W8, browse composed 0·85 of the dry matter (DM) intake in goats and 0·62 of the DM intake in sheep. A simultaneous analysis of foraging time allocation and relative diet composition revealed that both small ruminants were more efficient in consuming browse than herbaceous plants, more so in goats than sheep. It was concluded that vegetation availability and foraging habits affected dietary selection. Both sheep and goats only grazed when herbaceous plants were abundantly available; differences between ruminant species were apparent when herbaceous plants became scarcer, at which time goats browsed more and consumed proportionately more browse than sheep. The results contribute to better understanding of feeding behaviour and dietary selection of sheep and goats under natural desert pastures and could be useful in the management of mixed flocks.

Grazing behavior, dietary value and performance of sheep, goats, cattle and camels co-grazing range with mixed species of grazing and browsing plants

“…Accordingly, of the total time spent for forage harvesting by the animals 91, 42, 99 and 32% for sheep, goats, cattle and camels, respectively was spent on grazing, while the rest was spent for browsing. Camels and goats are known for their browsing choices ( Kam, El-Meccawi & Degen, 2012 ; Moges & Uden, 2005 ). Camels and goats were seen browsing dominantly on Acacia spp.…”

Resting and field metabolic rates of Awassi sheep and Baladi goats raised by Negev bedouin

“…Comparisons between sheep and goats have been made extensively, with most studies on behaviour, dietary selection, dietary intake and digestion (Ngwa et al ., 2000; Omphile et al ., 2004; Dove and Mayes, 2005; Sanon et al ., 2007; Kam et al ., 2012; Gonzales-Pech et al ., 2015; Askar et al ., 2016). We are aware of only a few studies in which FMR was compared in co-grazing sheep and goats, and, apparently, all originated from the same research team in Langston, Oklahoma.…”

“…The predominant plants are the annuals, Stipa capensis , Medicago radiate , Medicago truncatula , Echinops polyceras , Malva parviflora , Centaurea aegytiaca , Peganum harmala and Schismus arabicus , the trees Acacia saligna , Pistacia lentiscus and Tamarix aphylla and the shrubs Atriplex halimus , Lycium shawii and Retama raetam . Seasonal chemical composition and estimated metabolizable energy of these plants have been reported (Kam et al ., 2012). For the purpose of this paper, we were interested in whether the animal was grazing or browsing.…”

“…Activity budget was determined in six Awassi sheep and six Baladi goats by recording times of grazing, browsing and other activities of each animal for 5 min every hour during the 11 h grazing period over 2 days. The same six sheep and goats were observed, but selected randomly, each hour, and all measurements were made by the same observer, who had made these observations previously (Kam et al ., 2012). The sheep and goats were all males and about 1 year of age.…”

“…In a previous study, we found that the behaviour and dietary selection of sheep and goats tended to be similar at the peak of lush pasture, but differed with a decline in biomass availability and quality of the pasture (Kam et al ., 2012). This period is the most difficult for the free grazing animal, and energy requirements are often not met.…”