Neem leaves can be browsed or cut, dried and ground into leaf meal to be included in a concentrate diet (Puri, 1999). Fallen leaves may be used as fodder but they are less palatable. Neem leaves have been described as the forage of choice during dry periods and drought. For instance, in Gujarat, India, 15-20 kg/d of neem leaves were fed to cattle and buffalo during a famine in 1976 (Ketkar, 1976 cited by Puri, 1999).
Neem leaves are said to be palatable to camels and goats. In India, DM intakes of about 3% BW were reported in goats (Amanullah et al., 2006; Bais et al., 2002). During dry periods, neem leaves were palatable to cattle (Patel et al., 1957; Hentgen, 1985 cited by Puri, 1999).
Neem leaves have a relatively low nutritional value. In India, an estimated ME of 8.0 MJ/kg DM was reported (Ranjhan, 1980 cited by Puri, 1999). In Sudan, the in vitro OM digestibility of neem leaves was 51%, comparable to that of a local sorghum hay, but the estimated ME was much higher (10.0 vs. 7.8 MJ/kg DM) (Webb, 1988). In another in vitro study, the DM digestibility of neem leaves was 50% (Amanullah et al., 2006).
Sheep and goats
In a trial in Thailand, neem foliage was included at 20% in the diet of growing goats as a partial substitute for soybean meal without affecting productive performance, rumen fermentation and N balance (Srisaikham, 2009). In India, sheep fed on multi-nutrient blocks that contained 30% neem leaves, as a supplement to a sorghum stover-based diet, increased intake and digestibility while blood parameters remained unchanged (Raghuvansi et al., 2007a; Raghuvansi et al., 2007b).
Neem seed cake and neem seed kernel cake
Raw neem seed cake is unpalatable and harmful to ruminants as it adversely affects growth, the male reproductive system, and has at times led to haematuria. Consequently it should be fed to ruminants only after it has been detoxified to make it safe and palatable. Many processes have been tested including organic solvent extraction, acid or alkali treatment, water-washing, sun-drying and heating. Inclusion rates of 30-40% or more become feasible, but treatments such as water-washing or alkali treatment may also result in an important loss of nutrients, and the economic viability of such methods has not yet been established (Dutta et al., 2012).
Numerous trials in India with calves, buffalo bulls, crossbred bulls and sheep have shown that raw neem seed cake is unpalatable to ruminants due to the presence of limonoids. It is possible to improve its palatability by feeding it together with ingredients such as starch, molasses, maize or sugar from palm sap. Urea-ammoniated seed cake was found to be palatable to buffalo and kids (Dutta et al., 2012).
In crossbred dairy cows, water-washed neem seed kernel cake (protein 41% DM) was included at 40% in the concentrates without depressing DM intake, nutrient digestibility, milk yield, butter fat content and organoleptic evaluation of milk (Nath et al., 1989). Another experiment with 30% water-washed seed cake led to similar positive results. However, it was noted that water-washing was laborious and not feasible for industrial application, besides being uneconomical due to loss of soluble nutrients (Kumar et al., 1992).
Poor palatability, as well as depressed performance and nutrient digestibility, have been observed in crossbred calves fed concentrate mixtures containing 25 or 57% raw neem seed cake, and in buffalo calves fed diets where neem seed cake provided 25 to 50% of the dietary protein (Bedi et al., 1975a; Bedi et al., 1975b cited by Dutta et al., 2012). In crossbred calves, feeding a concentrate containing neem seed cake that contributed to 12.5, 25, or 50% of the crude protein requirement, resulted in poor palatability, reduced nutrient digestibility, poor weight gain or loss of body weight (Aruwayo et al., 2013). Water-washed and sun-dried neem seed kernel cake included at 45% in a concentrate mixture to male calves did not significantly alter growth, DM intake and nutrient digestilibility (Nath et al., 1983). Water-washed neem seed kernel cake included at 40% in a concentrate mixture to buffalo calves improved growth but lowered DM and carbohydrate digestibility (Agrawal et al., 1987). In buffalo calves, NaOH-treated and urea-treated neem seed kernel meal could be included at 40% in the diet, as a complete replacement for groundnut meal, with no effect on performance and blood biochemical parameters (Sastry et al., 1999).
Sheep and goats
Water-washed neem seed cake was included safely at rates of 30% in sheep diets and 20% in goat diets (Ramu et al., 1994). Likewise, water-washed neem seed kernel cake could be included in the diet of growing goats at up to 25-30% without deleterious effects on nutrient utilization, metabolism, carcass quality and organoleptic characteristics (Verma et al., 1995; Verma et al., 1996). Urea-treated neem seed kernel cake included at 33% in the concentrates for growing lambs was a satisfactory replacement of groundnut cake, though microcalculi were found in the kidneys (Musalia et al., 2000). Urea-ammonia treated neem seed kernel cake could be included at 22.5% in the concentrate for growing goats, replacing groundnut meal, with no effect on performance, and a better feed:gain ratio (Anandan et al., 1999).