Dates have been used for a long time to feed ruminants, due to local availability and low purchase costs. They have been used in sheep and cattle feed for both milk production and fattening. The nomadic Bedouins carry dates for their own consumption as well as their animals’ when desert grazing is inadequate (Williams, 1978). The nutritional potential of dates in ruminant diets has been studied in areas of production, where they can be a cheaper alternative energy source to cereal grains.
Digestibility and energy values
Due to their high carbohydrate content and relatively low fibre, dates have an energy value as high as that of cereal grains such as barley (Boudechiche et al., 2010), with an in vivo OM digestibility of about 83-89% (Rihani et al., 1988 ; Al-Yousef et al., 1993). Crude fibre digestibility was found to be variable, ranging from 38% (Al-Yousef et al., 1993) to 74% (Rihani et al., 1988). However, the main limitation of dates is their low protein value, and protein supplementation is required when dates are included at high levels in the diet (Rihani et al., 1988).
Dates are highly regarded as a feed by dairy cattle farmers (Robinson et al., 1973). It was noted that house cows kept by townspeople and oasis farmers tended to select the flesh and leave pits in the trough (Craig, 1975). Early research on the use of dates in dairy cow diets was judged inconclusive (Williams, 1978). Dates successfully replaced 25% and 50% of the concentrate ration of dairy cows although no increased performance resulted from the use of these feeds (Ali et al., 1956b). Date extracts fed as supplements to lactating cows did not lead to better performance in one experiment, and resulted in a loss of body weight in a second experiment (Robinson et al., 1973). Lactating Jersey cows fed fresh lucerne ad libitum and 6 kg of whole crushed dates did not lose weight, unlike the cows fed alfalfa alone, but their milk yield was lower. Protein intake, milk yield and weight gain were higher for cows fed 6 kg concentrate instead of 6 kg of dates (Robinson et al., 1974). In 2011, information was still lacking on the nutritional benefits of dates for dairy cows.
In fattening cattle, some of the concentrate ration may be replaced by dates without detriment to growth rate, provided that protein level is sufficient (Fine et al., 1956). Young bull calves fed 1 kg/d of dates in addition to alfalfa (fresh or hay) ad libitum had a lower growth rate and feed conversion efficiency than the animals fed only alfalfa (Robinson et al., 1973). Male calves fed 3 kg of alfalfa hay, 2.8 kg of dates and 0.2 kg of fish meal had a lower growth rate than animals fed alfafa and concentrate, which the authors suggest was due to the lower protein intake of the date-based diet (Robinson et al., 1974). However, the replacement of barley by dates (28% of diet on a DM basis) had no effect on total DM intake and live-weight change in Zebu dairy calves (El-Hag et al., 1992).
Many sheep studies have demonstrated that both date supplementation and the replacement of a cereal concentrate by dates can improve animal performance, due to the high energy content and high palatability of dates. Tested inclusion rates ranged from 5 to more than 50% of the diet DM. Usually, with dates below 25-30% of diet DM, there is no effect of replacement of the cereal (usually barley) by dates on voluntary intake, in vivo DM digestibility and live-weight gain (Al-Ani et al., 1991 ; Al-Dabeeb, 2005). In finishing lambs fed on concentrate-rich diets, the isonitrogenous replacement of barley by cull dates up to 30% of the diet increased total feed intake (+ 22%) and daily weight gain (+ 30%). Feed conversion efficiency was similar with 0, 15 and 30% of dates in the diet, but DM, NDF and ADF digestibilities were the highest at the 30% rate (Alhomidy et al., 2011). However, decreased digestibility and weight gain at 30% inclusion rate of dates have also been observed in male lambs (Al-Ani et al., 1991).
At higher incorporation rates (45-50%), there are some risks of decreased diet digestibility (Al-Ani et al., 1991; Hmeidan et al., 1993) and laxative effect (Al-Yousef et al., 1993). Dried dates have however been used up to 50-55% of the diet without health problems in fattening lambs (Rihani et al., 1988). Early research showed that concentrates containing up to 45% macerated dates could promote satisfactory gains particularly with protein-rich forages (Ali et al., 1956a; Sarsam et al., 1954).
Up to 15% dates can be added to forage before ensiling (Ziaei, 2010).
Supplementing grazing ewes at the end of lactation with 0.35 kg/d of cull dates improved milk production and the growth performance of their lambs (Boudechiche et al., 2010; Mebirouk-Boudechiche et al., 2011). Replacement of barley by cull dates in the diets of breeding ewes in preparation for mating did not affect DM intake, DM digestibility and ovulation rate up to 35% of dates in the diet. Higher inclusion rates (50 to 75%) decreased weight and ovulation rate, and, at 75%, resulted in a lower litter size per ewe. No symptoms of acidosis or change in rumen fermentation were observed at the highest proportion of cull dates despite the high concentration in fermentable carbohydrates (Rekik et al., 2008).
Dromedaries can be fed with cull dates, but in an experiment comparing the use of date by-products by sheep and dromedaries, dromedaries did not benefit as well as sheep from the inclusion of cull dates, and the optimal inclusion rate for weight gain was 25%. This may be explained by the better adaptation of dromedaries to the utilization of lignocellulosic materials and their lesser adaptation to cytoplasmic sugars (Chehma et al., 2002b; Chehma et al., 2004).