There is no generally accepted optimal feed form and delivery method for feeding finisher pigs. The objective of this study was to compare the effect of feed form (meal and pellet) and delivery method (liquid, dry, and wet/dry) on feed microbiology and growth, gain-to-feed ratio (G:F), and carcass quality of finisher pigs. Two batches of pigs were used, each with six pen replicates per treatment. In each batch 216 pigs (32.7 kg; ± 0.48 SE) housed in same-sex (entire male or female) pens of six pigs per pen were on treatment for ~62 d prior to slaughter. The experiment was a 2 × 3 factorial arrangement with two factors for diet form (meal and pellets) and three factors for feed delivery (dry, wet/dry, liquid). The treatments were 1) meal from dry feeder, 2) meal from wet/dry feeder, 3) meal from liquid system, 4) pellet from dry feeder, 5) pellet from wet/dry feeder, and 6) pellet from liquid system. Pig growth performance was determined, blood samples collected at slaughter for hematological analysis and microbiological and proximate analysis of feed performed. A significant feed form × delivery interaction was found for G:F. During the overall period G:F was 0.446, 0.433, 0.423, 0.474, 0.459, and 0.418 g/g (SE = 0.0080; P < 0.01) for treatments 1 through 6, respectively. When feed was pelleted, G:F was improved when feed delivery was dry or wet/dry compared to meal but when the delivery was liquid, pelleting did not affect G:F. There were no interactive effects for overall average daily gain (ADG). Overall ADG was 1,114 and 1,156 g/d (SE = 16.9; P < 0.01) for pigs fed diets in meal and pellet form, respectively and 1,080, 1,114, and 1,210 g/d (SE = 18.4; P < 0.001) for dry-, wet/dry-, and liquid-fed pigs, respectively. Carcass weight was 76.6 and 79.0 kg (SE = 0.55; P < 0.001) for pigs fed in meal and pellet form, respectively, while it was 74.7, 77.3, and 81.5 kg (SE = 0.60; P < 0.001) for pigs delivered dry, wet/dry, and liquid diets, respectively. Lactic acid bacteria (P < 0.05) and yeast (P < 0.01) counts in troughs were greater for the liquid than the dry diet in both meal and pelleted form. There was also evidence of lysine degradation in the liquid diet but this did not impact pig growth. Feeding the diet in pelleted vs. meal form led to lower hemoglobin and greater white blood cell and neutrophil counts (P < 0.05). To conclude, wet/dry feeding of a pelleted diet is recommended to maximize growth rate while optimizing G:F in grow-finisher pigs.

Aims To investigate the microbiological and nutritional quality of liquid finisher pig feed on commercial production units and the factors influencing this. Methods and results Microbiological and physio‐chemical analyses were performed on liquid feed sampled from the mixing tank and troughs of the finisher section of eight commercial pig units. Lactic acid bacteria, yeast and Escherichia coli counts, as well as lactic acid, ethanol and acetate concentrations were higher in residual feed sampled from the troughs compared with mixing tank samples (P < 0·001). Feed pH, as well as lysine, methionine and threonine concentrations and gross energy were all lower in the residual trough samples (P < 0·001). Liquid co‐products reduced E. coli counts in the residual trough samples (P < 0·05), pH in the mixing tank (P < 0·01) and fresh trough samples (P < 0·05) and mould counts at all three sampling locations (P < 0·01) but sanitation practices had no impact. Conclusions Even when considered unfermented, a considerable degree of spontaneous fermentation occurs in liquid feed, with resultant negative effects on nutritional quality. Significance and Impact of the Study This is one of the first studies showing that uncontrolled fermentation of fresh liquid pig feed is commonplace on commercial units, highlighting the need for implementation of suitable control strategies.

The optimum proportion of water for preparing liquid feed to maximize growth and optimize feed efficiency (FE) in growing-finishing pigs is not known. The aim of the current study was, using an automatic short-trough sensor liquid feeding system, to identify the water-to-feed ratio at which growth was maximized and feed was most efficiently converted to live-weight. Two experiments were conducted in which four commercially used water-to-feed ratios were fed: 2.4:1, 3.0:1, 3.5:1, and 4.1:1 on a dry matter (DM) basis (the equivalent of 2:1, 2.5:1, 3.0:1, and 3.5:1 on a fresh matter basis). Each experiment comprised 216 pigs, penned in groups of 6 same sex (entire male and female) pigs/pen with a total of 9 pen replicates per treatment. The first experiment lasted 62 days (from 40.6 to 102.2 kg at slaughter) and the second experiment was for 76 days (from 31.8 to 119.6 kg at slaughter). Overall, in Exp. 1, FE was 0.421, 0.420, 0.453, and 0.448 (s.e. 0.0081 g/g; P &lt; 0.01) for pigs fed at 2.4:1, 3.0:1, 3.5:1, and 4.1:1, respectively. Overall, in Exp. 2, average daily gain was 1,233, 1,206, 1,211, and 1,177 (s.e. 12.7 g/day; P &lt; 0.05) for pigs fed at 2.4:1, 3.0:1, 3.5:1, and 4.1:1, respectively. At slaughter, in Exp. 1, dressing percentage was 76.7, 76.6, 76.7, and 75.8 (s.e. 0.17%; P &lt; 0.01) for 2.4:1, 3.0:1, 3.5:1, and 4.1:1, respectively. There were no differences between treatment groups for DM, organic matter, nitrogen, gross energy, or ash digestibilities. These findings indicate that liquid feeding a diet prepared at a water-to-feed ratio of 3.5:1 maximizes FE of growing-finishing pigs without negatively affecting dressing percentage. Therefore, preparing liquid feed for growing-finishing pigs at a water-to-feed ratio of 3.5:1 DM is our recommendation for a short-trough liquid feeding system.