Yellow grease in sheep diets: intake and digestibility

ABSTRACT This study aimed to assess the effects of yellow grease supplementation on the intake, digestibility, and nitrogen balance in sheep. Twenty Santa Inês lambs with a mean age of 95 ± 10 d and body weight of 19.29 ± 3.17kg were evaluated in a completely randomized design. The diets were supplemented with oil at concentrations of 0, 20, 40, 60, and 80 gkg-1 of dry matter (DM) of the concentrate. The diets were based on roughage and concentrate (50:50). The experimental period lasted 19 d and included 14 adaptation days and five collection days for the total supplied diet, orts, feces, and urine. Supplementation with yellow grease had no significant effect on the intake of DM, crude protein (CP), neutral detergent fiber (NDF), or non-fiber carbohydrates (NFC). However, the ether extract (EE) intake increased linearly with supplementation of yellow grease. Moreover, no effect was observed for DM, CP, NDF, and NFC digestibility and nitrogen balance. EE digestibility increased linearly with the yellow grease dietary supplementation. Thus, sheep dietary supplementation with yellow grease may be used at a level of up to 80 gkg-1 of DM of concentrate without impairing nutrient intake and digestibility.

Grease trap waste (griddle grease) as feed ingredient for finishing lambs: growth performance, dietary energetics, and carcass characteristics

Forty-eight (37.7±3.4 kg, initial shrunk live weight) lambs were used in a 61-d experiment to evaluate the energy value of grease trap waste (GT) at four levels of supplementation (0, 2, 4, and 6%). Supplemental GT replaced cracked corn in the basal diet. The GT contained 6.4% moisture, 3.1% impurities, and 79.8% total fatty acids (FA). Increasing GT level in diets did not affect dry matter intake and daily gain weight, but linearly increased gain efficiency and estimated dietary net energy (NE). However, the ratio of observed-to-expected diet NE decreased with increasing level of GT. The estimated NE values for GT based on FA intake were in close agreement (98 and 102% of predicted, respectively) with those NE values determined by replacement technique for 2 and 4% supplementation level. However, the observed NE value for GT supplemented at the 6% level was 9% lower than predicted. Kidney-pelvic-hearth fat increased as level of GT supplementation increased; otherwise, carcass characteristics and shoulder composition were not affected. We conclude that GT is a suitable alternative to conventional feed fats in diets for finishing lambs. The estimated NE of GT is 93% than energy value assigned by current standards for tallow and yellow grease.

Biodiesel Blends Startability and Emissions During Cold, Warm and Hot Conditions

The time and emissions during cold starting were investigated at cold and hot temperatures (i. e., – 10°C, 0 °C, 25°C and 50 °C). The effect of injection timing (IT) on these factors was also studied at four ITs before top dead centre (BTDC) i. e., (12 , 15 , 20 and 23 BTDC). The results were compared with engine operation at 17 BTDC (factory IT). Sunflower vegetable oil and yellow grease were used as raw materials to prepare bio diesel fuels through transesterification. B20 (20% sunflower oil biodiesel+80% diesel) and W20 (20% yellow grease biodiesel+80% diesel), together with neat conventional Iraqi diesel fuel, were used to analyse engine startability and emissions under cold and hot starting conditions. Results indicated that adding biofuel affects the engine starting response and that the starting time stabilises at high starting temperatures. At a low starting temperature (i. e.,–10 °C), hydrocarbon (HC) and carbon monoxide (CO) concentrations increase significantly. At moderate and high starting temperatures, the oxygen content in the biofuel blend plays a dominant role in reducing the HC and CO concentrations. Smoke opacity has increased notably for the biodiesel blends at low starting temperatures but has decreased significantly at moderate and high starting temperatures. Both biofuel blends emit higher levels of nitrogen oxide than the neat diesel fuel. Noise increases at low starting temperatures, thereby indicating rough combustion.

Comparative effects of ‘solid’-fat sources as a substitute for yellow grease on digestion of diets for feedlot cattle

Five cannulated Holstein steers fed a steam-flaked corn-based growing diet containing 40% of alfalfa hay were used in a 5 × 5 Latin square design to examine the effect of ‘solid’ supplemental fats as a substitute for yellow grease (YG) on the extent and site of digestion. Treatments were (% of diet DM) as follows: (1) no supplemental fat; (2) 5% YG; (3) 5.88% calcium soaps (ML); (4) 5% flaked palmitic acid (RP10); and (5) 5% hydrogenated palm fatty acid distillate (HPFAD). Supplemental fats replaced the corn in the control diet. Supplemental fat decreased (P < 0.01) ruminal and total-tract digestion of organic matter and tended to decrease (P = 0.06) ruminal digestion of neutral detergent fibre, with no effects on ruminal digestion of feed N, microbial N efficiency, or total-tract digestion of N and neutral detergent fibre. With the exception of RP10, fat supplementation decreased (P < 0.03) postruminal digestion of C18:0. Compared with the original C16:0:C18:0 ratio of solid fats, the C16:0:C18:0 ratio of fatty acids (FAs) entering the small intestine markedly decreased for all solid-fat treatments. Ruminal biohydrogenation of YG and ML were 73% and 49% respectively. On the basis of FA intake, postruminal FA digestion of YG, ML, RP10 and HPFAD was 0.97, 0.94, 0.92 and 0.80 of expected respectively. This experiment confirmed that postruminal digestion of total FAs of conventional supplemental yellow grease is a predictable function of total FA intake per unit of bodyweight. However, in the case sources of the solids fats, this relationship (FA intake and postruminal digestion of FAs) was less consistent. This may be due to their physical and chemical nature (saturatedFA:unsaturated FA ratio). On the basis of the nutrient digestion and postruminal FA digestibility observed in the present experiment, solid supplemental fats do not afford appreciable advantages over conventional YG when supplemented in growing diets (forage level ~400 g/kg diet DM) for feedlot steers.