Yellow grease as an alternative energy source for nursing Awassi ewes and their suckling lambs

Thirty Awassi ewes with an initial body weight (BW) of 52.0 kg (SD = 8.4) nursing single lambs with an initial BW of 6.2 kg (SD = 1.0) were utilized to study yellow grease, by partially replacing barley, as an alternative energy source. The ewes aged 3–7 years and parity ranged from 2 to 6. All ewes gave birth 6–8 days before starting the experiment. Ewes with their lambs were individually housed in shaded pens (1.5 m × 0.75 m). Ewes and their lambs were randomly assigned to one of three dietary treatments (10 ewes with their lambs per treatment): no added fat (control), 32 g/kg added fat as yellow grease (restaurant fat; YG), or as soybean oil (SO) by partially replacing barley in the control diet. All diets were formulated to be isonitrogenous, isocaloric, and to meet all nutrient requirements for nursing ewes. For ewes, dry matter intake (DMI; P=0.67), milk yield (P=0.42), BW change (P=0.27), milk composition (P>0.20), and milk composition yields (P>0.30) were not affected by dietary treatments. Average daily gain (ADG) of lambs was not affected (P=0.6) by dietary treatments. However, the cost of feeding 10 ewes for 55 days was US $612, 544, and 601 for the control, YG, and SO group, respectively. Additionally, the cost of producing 1 kg of milk was US $1.84, 1.37, and 1.52 for the control, YG, and SO group, respectively. Under conditions similar to our study, it is economically feasible to partially (206 g/kg) replace barley with YG without adversely affecting the performance of nursing Awassi ewes or their suckling lambs.