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Three diets based on by-products (maize gluten, maize gluten feed, pollard and rapeseed) and three based on wheat and barley were formulated. 40g/kg of vegetable oil blend was included in 2 diets by-product-based and 2 wheat/barley-based. Therefore within the by-product-based and wheat/barley-based diets there were three treatments (1) no oil applied (Basal); (2) 40 g/kg oil incorporated into the pellet through the mixer (40 IN) and (3) 10 g/kg oil incorporated into the pellet through the mixer and 30 g/kg sprayed onto the pellet after the pellet was formed (10 IN + 30 SP). The coefficient of total tract apparent digestibility (CTTAD) of each diet was determined using a total of 48 Landrace×Large White boars (average weight 50.4 kg, SD = 3.5 kg) from the research pig herd. Pigs were offered one of the six experimental diets on an ad libitum basis. After a 14-day pre-feed period (7 days of which pigs were housed in individual pens followed by 7 days in digestibility crates), total faeces and urine were collected over a further 7-day period while pigs remained in the crates. The performance trial was conducted with 960 Landrace×Large White pigs (commercial unit). At 14 weeks of age, pigs were weighed (45.6 kg, SD = 3.2) and allocated into groups of 20 into standard finishing accommodation. They were offered the experimental diets on an ad libitum basis for on average 70 days (SD = 8.9 days) until slaughtered. Pigs were slaughtered in a commercial abattoir at an average age of 24 weeks. Growth rate, feed intake and FCR over the experimental period were recorded. Empty hot carcass weight and carcass fatness were measured 45 min post-slaughter. Carcass gain and feed:carcass conversion ratio were then calculated.
There were significant interactions between diet and oil application for DM and CP CTTAD (both P<0.05). DM and CP CTTAD were similar across the three by-product-based diets, but when oil was included in the wheat/barley-based diets DM and CP CTTAD increased. Oil addition (40IN and 10IN + 30SP) reduced the total amount of N excreted (P<0.05) when using wheat/barley-based diets and the total amount of P (P<0.01) excreted when either by-product-based or wheat/barley-based diets were offered. Average daily gain (P<0.001), finish weight (P<0.01) and carcass weight (P<0.001) were higher and FCR was improved (P<0.001) when wheat/barley-based diets were offered compared with by-product-based diets.
It is concluded that the oil inclusion (40 g/kg inclusion) to pelleted by-product-based or wheat/barley-based diets by either spraying onto, or totally incorporating within the pellet, do not produce detrimental effects on pig performance or the CTTAD, maintaining similar the carcass quality of pigs with both diets.
E Magowan, MEE McCann, VE Beattie, KJ McCracken, W Henry, S Smyth, R Bradford, FJ Gordon, and CS Mayne, 2010. Animal Feed Science and Technology, 156:89–96.
