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Effects of an abrupt change between diet form on growth performance of finishing pigs
Animal Feed Science and Technology 211 (2016) 132–136
Contents lists available at ScienceDirect
Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci
Effects of an abrupt change between diet form on growth performance of finishing pigs C.B. Paulk ∗ , J.D. Hancock Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506, USA
a r t i c l e
i n f o
Article history: Received 6 August 2015 Received in revised form 23 October 2015 Accepted 30 October 2015 Keywords: Feed processing Change Pellets Finishing pigs
a b s t r a c t A total of 200 finishing pigs (PIC TR4 × 1050; initially 60 ± 4.7 kg) were used in a 58 days growth assay to determine the effects of an abrupt change in diet form from meal to pelleted and pelleted to meal diets on growth performance and carcass measurements. The experiment was designed as a randomized complete block design with 5 pigs per pen and 10 pens per treatment. Diets were fed in 2 phases, day 0–36 and day 36–58 for phase 1 and 2, respectively. Treatments were meal to meal, meal to pelleted, pelleted to meal, and pelleted to pelleted diets for Phases 1 and 2 of the experiment, respectively. For Phase 1 (day 0–36), pigs fed the mean of the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the mean of the meal diet. For Phase 2 (day 36–58), pigs fed the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diets. Pigs fed the pelleted diet from day 0 to 58 had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet from day 0 to 58. For day 0–58, pigs fed the pelleted diet for either Phase 1 or 2, but not both, tended to have decreased (P < 0.11) ADG and G:F compared to those fed the pelleted diet for the entire experiment. Pigs fed the meal then pelleted diet did not differ (P > 0.27) in performance compared to those fed the pelleted then meal diet. No differences (P > 0.19) were observed in dressing percentage, fat thickness, loin depth, or percentage fat free lean index. In conclusion, pigs fed the pelleted diet the entire experiment had increased ADG compared to pigs fed the meal diet. Pigs fed the pelleted diet had the greatest G:F, pigs fed meal the worst, and pigs fed pellets for only part of the grow-finish phase fell between the other treatments. Published by Elsevier B.V.
1. Introduction Feed processing technologies can be used to maximize feed utilization. Pelleting swine diets has been shown to improve efficiency of gain (Wondra et al., 1995a). However, adding the necessary infrastructure to allow for pelleting a diet consist of a high initial cost, along with decreasing production rates, and increasing energy usage, which leads to higher feed cost for the producer. This could be a potential problem with an increase in pork and chicken demands. Not being able to achieve adequate production rates could be a problem for some feed manufactures. Therefore, swine producers may not be able to feed pelleted diets throughout the entire growing-finishing phase. Data has not been reported on the effects of switching from meal to pelleted diets and vice versa and if feeding pelleted diets throughout the entire
Abbreviations: ADG, average daily gain; ADFI, average daily feed intake; G:F, g of gain per kg of feed. ∗ Corresponding author. Current address: Department of Animal Science, Texas A&M University, College Station, TX 77840, USA. E-mail address: [email protected] (C.B. Paulk). http://dx.doi.org/10.1016/j.anifeedsci.2015.10.017 0377-8401/Published by Elsevier B.V.
C.B. Paulk, J.D. Hancock / Animal Feed Science and Technology 211 (2016) 132–136
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Table 1 Composition of diets (as-fed basis). Item (g/kg)
Phase 1a
Phase 2b
Corn Soybean meal Choice white grease l-Lysine HCl dl-Methionine l-Threonine l-Tryptophan Monocalcium phosphate Limestone Salt Vitamin premixc Mineral premixd Folic acide Antibioticf
792.5 171.5 10.0 3.4 0.70 1.17 0.23 7.2 9.1 2.5 0.8 0.4 0.01 0.5
847.0 119.0 10.0 3.5 0.48 1.10 0.37 5.4 8.9 2.5 0.8 0.4 0.01 0.5
Calculated analysis (g/kg) Standardized ileal digestible lysine Calcium Phosphorus
8.8 5.5 4.9
7.6 5.0 4.3
a
Diets fed in meal or pelleted form from day 0 to 36. Diets fed in meal or pelleted form from day 36 to 58. c Supplied (per kilogram of diet) 1764 IU vitamin A from vitamin A acetate, 265 IU vitamin D from vitamin D3 , 7.05 IU vitamin E d-␣-tocophorol acetate, 0.71 mg vitamin K from menadione nicotinamide bisulfite, 6.2 g vitamin B12 from cyanocobalamin, 7.9 mg niacin from niacinamide, 4.4 mg pantothenic acid from calcium pantothenate, and 1.32 mg riboflavin from crystalline riboflavin. d Provided (per kilogram of diet) 39.7 mg manganese from manganese oxide, 165 mg iron from iron sulfate, 165 mg zinc from zinc oxide, 16.5 mg copper from copper sulfate, 0.298 mg iodine from calcium iodate, and 0.298 mg selenium from sodium selenite. e Provided (per kilogram of diet) 1 mg folic acid. f Tylan 40 (Elanco Animal Health, Greenfield, IN) provided 44 mg of tylosin as tylosin phosphate per kg of complete diet. For control of swine dysentery associated with Brachyspira hyodysenteriae, and for control of porcine proliferative enteropathies (ileitis) associated with Lawsonia intracellularis. b
grower and finisher stage is necessary to achieve performance benefits. Therefore, our objective was to determine the effects of abrupt changes between meal and pelleted diets on growth performance of finishing pigs. 2. Materials and methods All experimental procedures were approved by the Institutional Animal Care and Use Committee at Kansas State University. 2.1. Experimental design All feed processing was completed at a commercial feed mill (Key Feeds, Clay Center, KS). For all diets, corn was milled through a hammer mill (Jacobseen P24209 Series 2) with a screen size of 3.18 mm (full circle screen). The ASAE (1983) standard method was used to determine the particle size of milled corn. Tyler sieves, with numbers 6, 8, 10, 14, 20, 28, 35, 48, 65, 100, 150, 200, 270, and a pan, were used for particle size determination. A Ro-Tap® shaker (W. S. Tyler, Mentor, OH) was used to sift the 100 g samples for 10 min. A geometric mean particle size (dgw) was calculated by measuring the amount of ground grain remaining on each screen. The pelleted diets were pelleted in a 125 horsepower pellet mill (Century, California Pellet Mill, San Francisco) and the die had 4.8 mm openings. Pellets were analyzed for pellet durability index (ASAE, 1987) and modified pellet durability index by altering the procedure by adding 5 13-mm hexagonal nuts prior to tumbling. A total of 200 finishing pigs (TR4 × PIC 1050; Hendersonville, TN) with an average initial body weight of 60 ± 4.7 kg were used in a 58-day growth assay. The pigs were weighed prior to the experiment and blocked by body weight. Pigs were then assigned to concrete slatted flooring pens (3 barrows and 2 gilts placed in each pen) that were 2.44 m × 1.53 m. Each pen consisted of a nipple waterer and single-hole self-feeder allowing ad libitum consumption of feed and water. There were a total of 40 pens, with 5 pigs per pen 10 pens per treatment. All diets (Table 1) were the same formulation fed in either meal or pellet form. Diets were fed in 2 phases, day 0–36 and day 36–58 for phase 1 and 2, respectively. All nutrients met or exceeded NRC recommendations (NRC, 1998). Treatments were meal to meal, meal to pelleted, pelleted to meal, and pelleted to pelleted diets for phases 1 and 2 of the experiment. Pigs and feeders were weighed on day 0, 36, and 58 to determine ADG, ADFI, and G:F. Feed wastage was not prevented in any manner; therefore, ADFI is a measure of feed disappearance. On day 58 of the experiment, pigs (average body weight of 128 ± 2.37 kg) were tattooed and shipped to a commercial abattoir (Farmland Foods, Inc.; Crete, NE) for slaughter the following morning. Measurements were acquired
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immediately after slaughter for hot carcass weight, loin depth, and 10th rib fat thickness (SFK Technology A/S model S 82; Herlev, Denmark). Dressing was calculated as hot carcass weight divided by preshipping live weight. Carcass fat free lean percentage was calculated with fat free lean index as a percentage of hot carcass weight. Fat free lean index was calculated using the equation suggested by the National Pork Producers Council (NPPC, 2001). 2.2. Statistical analyses Data was analyzed as a randomized complete block design using the MIXED procedure of SAS (v9.1; SAS Inst. Inc., Cary, NC) with block representing initial weight and pen location within a single blocking criterion and pen as the experimental unit. Dietary treatment was included in the model statement as the fixed effect. For day 0–36 and 36–58 the main effect of meal vs. pelleted diets were compared. For the overall experiment (day 0–58), orthogonal contrasts were used to separate treatment means with comparisons of: (1) control vs. pelleted treatments fed from day 0 to 58; (2) treatments pelleted for the entire experiment vs. treatments pelleted for either phase 1 or 2 but not both; (3) treatments fed in pelleted form for phase 1 and meal form for phase 2 vs. treatments fed in meal form for phase 1 and pelleted form for phase 2. 3. Results 3.1. Feed processing characteristics For phase 1 and phase 2 the pelleted diets resulted in pellet durability indexes of 86 and 87% and modified pellet durability indexes of 80 and 77%, respectively. The average mean particle size for ground corn was 433 m. 3.2. Growth performance For day 0–36, pigs fed the mean of the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet (Table 2). For day 36–58, pigs fed the pelleted diet had increased (P < 0.01) ADG and G:F compared to those fed the meal diet. Overall (day 0–58), pigs fed the pelleted for the entire experiment diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet. For day 0–58, pigs fed the pelleted diet for either Phase 1 or 2, but not both, tended to have decreased (P < 0.11) ADG and G:F compared to those fed the pelleted diet for the entire experiment. Pigs fed the meal then pelleted diet did not differ (P > 0.27) in performance compared to those fed the pelleted then meal diet. There was a tendency for pigs fed the meal diet for the entire experiment to have a decreased (P < 0.10) final body weight and hot carcass weight compared to those fed the pelleted diet for the entire experiment. No differences in treatments (P > 0.15) were observed in dressing, fat thickness, loin depth or percentage fat free lean index. Table 2 Effects of abrupt change between meal and pelleted diets on growth performance in finishing pigsa Item
Day 0–36 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Day 36–58 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Day 0–58 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Final body weight (kg) Hot carcass weight (kg) Dressingc Backfat thickness (mm) Loin depth (mm) Fat-free lean indexd (%)
Meal to meal
Meal to pellet
Pellet to meal
Pellet to pellet
SE
Probabilityb,c (P<) 1
2
3
1115 2.88 388
1132 2.87 397
1170 2.76 423
1164 2.76 423
29.2 0.090 5.9
0.01 0.17 0.001
– – –
– – –
1161 3.53 330
1231 3.46 358
1118 3.42 327
1239 3.50 355
25.2 0.094 6.3
0.01 0.92 0.001
– – –
– – –
1132 3.12 363
1170 3.09 380
1150 3.01 382
1192 3.04 393
24.2 0.088 7.1
0.01 0.28 0.001
0.11 0.83 0.06
0.39 0.27 0.85
126.0 94.1 0.746 18.7 66.5 52.2
128.3 95.3 0.743 19.8 67.3 51.6
127.2 95.0 0.743 19.6 68.2 51.7
129.0 95.9 0.744 19.8 67.5 51.6
2.37 1.71 0.0025 1.00 0.84 0.61
0.10 0.10 0.71 0.19 0.40 0.26
0.35 0.41 0.61 0.83 0.84 0.83
0.49 0.78 0.97 0.82 0.46 0.86
A total of 200 pigs (average initial BW of 60 ± 4.7 kg) were used in 58 days growth assay The contrast statement for Phases 1 and 2 compared meal vs. pelleted diets within the respective phase. Contrast statements for the overall experiment were: (1) meal vs. pelleted diet for the entire experiment; (2) Pelleted diets fed for entire experiment vs. pelleted diets fed for only part of experiment; (3) Meal to pellet vs. pellet to meal c Dressing = hot carcass weight divided by preshipping live weight. d Fat-free lean index, calculated using NPPC (2001) equation, as a percentage of hot carcass weight. a
b
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4. Discussion The experiment reported herein observed a 5 and 8% improvement in ADG and G:F when pigs were fed pelleted diets compared to those fed meal diets, respectively. This is in agreement with previous research that reported improvements in ADG and G:F when pelleting swine diets (Baird, 1973; Chamberlain et al., 1967; Hanke et al., 1972; Wondra et al., 1995a). There are a number of theories that try and explain the mechanism behind the improvement in growth performance do to pelleting diets. Skoch et al. (1983) proposed the idea that pelleting increased the bulk density of diets and reduced dustiness, therefore, making the diets more palatable. However, this is not supported by the inconsistencies observed with feed intake in pelleting experiments. Jensen and Becker (1965) observed pelleted diets having improved carbohydrate fraction susceptibility to in vitro enzymatic digestion compared to meal diets. Moreover, Wondra et al. (1995a,b) reported improvements in DM, N, and gross energy apparent total tract digestibilities due to pelleting. Similarly, Le Gall et al. (2009) demonstrated improvements in OM and energy apparent total tract digestibility with pelleting. However, the authors did not observe improvements in fecal apparent total tract N digestibility with pelleting. Stein and Bohlke (2007) also demonstrated no improvements in N and amino acid digestibility with pelleting. Therefore, a portion of the improvement in performance may be associated with improvements in energy digestibility. Although, stomach ulceration and keratinization were not measured in the study reported herein, it is also important to consider what processing factors influence gut morphology and how to maximize efficiency without inducing ulceration. It was previously determined that fine grinding can have negative effects on stomach morphology (Mahan et al., 1966; Maxwell et al., 1970; Ayles et al., 1996), but it has also been reported that pelleting can also increase the incidences of ulceration of the pars esophageal region of the stomach (Millet et al., 2012; Paulk et al., 2015). It has been hypothesized that this is due to the increased fluidity of stomach contents, which results in more mixing of stomach contents. Mixing of the fluid stomach content allows for continuous exposure of the unprotected mucosa of the esophageal region to pepsin and digestive acids (Reimann et al., 1968; Maxwell et al., 1970, 1972). Although pelleting diet may negatively impact stomach morphology, there were no mortalities during the experiment reported herein. Abrupt changes between meal and pelleted diets did not result in overall negative or positive effects on growth performance of finishing pigs. Pigs fed pelleted diets for half and meal diets for the other half of the experiment had performance intermediate to those fed the pelleted or meal diet for the entire experiment. 5. Conclusion In conclusion, pigs fed the pelleted diet the entire experiment had increased ADG compared to pigs fed the meal diet. Pigs fed the pelleted diet had the greatest G:F, pigs fed meal the worst, and pigs fed pellets for only part of the grow-finish phase fell between the other treatments. Conflict of interest The authors declare that there are no conflicts of interest. References ASAE, 1983. Method of determining and expressing fineness of feed materials by sieving. In: ASAE Standard S319, Agricultural Engineers Yearbook of Standards. American Society of Agricultural Engineers, pp. 325. ASAE, 1987. Wafers, pellets, and crumbles – definitions and methods for determining density, durability, and moisture content. In: ASAE Standard S269.3, Agricultural Engineers Yearbook of Standards. American Society Agricultural Engineers, pp. 318. Ayles, H.L., Friendship, R.M., Ball, R.O., 1996. Effect of dietary particle size on gastric ulcers, assessed by endoscopic examination, and relationship between ulcer severity and growth performance of individually fed pigs. Swine Health Prod. 4, 211–216. Baird, D.M., 1973. Influence of pelleting swine diets on metabolizable energy, growth and carcass characteristics. J. Anim. Sci. 36, 516–521. Chamberlain, C.C., Meeeiman, G.M., Lidvall, E.R., Gamble, C.T., 1967. Effects of feed processing method and diet form on the incidence of esophagogastric ulcers in swine. J. Anim. Sci. 26, 72–75. Hanke, H.E., Rust, J.W., Meade, R.J., Hanson, L.E., 1972. Influence of source of soybean protein and of pelleting on rate of gain and gain/feed of growing swine. J. Anim. Sci. 35, 958–962. Jensen, A.H., Becker, D.E., 1965. Effect of pelleting diets and dietary components on the performance of young pigs. J. Anim. Sci. 24, 392–397. Le Gall, M., Warpechowski, M., Jaguelin-Peyraud, Y., Noblet, J., 2009. Influence of dietary fiber level and pelleting on the digestibility of energy and nutrients in growing pigs and adult sows. Int. J. Anim. Biosci. 3, 352–359. Mahan, D.C., Pickett, R.A., Perry, T.W., Curtin, T.M., Featherson, M.R., Beeson, W.M., 1966. Influence of various nutritional factors and physical form of feed on esophagogastric ulcers in swine. J. Anim. Sci. 25, 1019–1023. Maxwell, C.V., Reimann, E.M., Hoekstra, W.G., Kowalczyk, T., Benevenga, N.J., Grummer, R., 1970. Effect of dietary particle size on lesion development and on the contents of various regions of the swine stomach. J. Anim. Sci. 30, 911–922. Maxwell, C.V., Reimann, E.M., Hoekstra, W.G., Kowalczyk, T., Benevenga, N.J., Grummer, R.H., 1972. Use of tritiated water to assess, in vivo, the effect of dietary particle size on the mixing of stomach contents of swine. J. Anim. Sci. 34, 212–216. Millet, S., Kumar, S., De Boever, J., Ducatelle, R., De, D., Bradbander, 2012. Effect of feed processing on growth performance and gastric mucosa integrity in pigs from weaning until slaughter. Anim. Feed Sci. Technol. 175, 175–181. NPPC, 2001. Procedures for Estimating Pork Carcass Composition. National Pork Producers Council and American Meat Science Association, Des Moines, IA. NRC, 1998. Nutrient Requirement for Swine, 10th rev. ed. Natl. Acad. Press, Washington, DC. Paulk, C.B., Hancock, J.D., Fahrenholz, A.C., Wilson, J.M., McKinney, L.J., Benhke, K.C., Nietfeld, J.C., 2015. Effects of feeding cracked corn to nursery and finishing pigs. J. Anim. Sci. 93, 1710–1720.
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Reimann, E.M., Maxwell, C.V., Kowalczyk, T., Benevenga, N.J., Grummer, R.H., Hoekstra, W.G., 1968. Effect of fineness of grind of corn on gastric lesions and contents of swine. J. Anim. Sci. 27, 992–999. Skoch, E.R., Binder, S.F., Deyoe, C.W., Allee, G.L., Behnke, K.C., 1983. Effects of pelleting conditions on performance of pigs fed a corn-soybean meal diet. J. Anim. Sci. 57, 922–928. Stein, H.H., Bohlke, R.A., 2007. The effects of thermal treatment of field peas (Pisum sativum L.) on nutrient and energy digestibility by growing pigs. J. Anim. Sci. 85, 1424–1431. Wondra, K.J., Hancock, J.D., Behnke, K.C., Hines, R.H., Stark, C.R., 1995a. Effects of particle size and pelleting on growth performance, nutrient digestibility, and stomach morphology in finishing pigs. J. Anim. Sci. 73, 421–426. Wondra, K.J., Hancock, J.D., Behnke, K.C., Stark, C.R., 1995b. Effects of mill type and particle size uniformity on growth performance, nutrient digestibility, and stomach morphology in finishing pigs. J. Anim. Sci. 73, 2564–2573.
Contents lists available at ScienceDirect
Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci
Effects of an abrupt change between diet form on growth performance of finishing pigs C.B. Paulk ∗ , J.D. Hancock Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506, USA
a r t i c l e
i n f o
Article history: Received 6 August 2015 Received in revised form 23 October 2015 Accepted 30 October 2015 Keywords: Feed processing Change Pellets Finishing pigs
a b s t r a c t A total of 200 finishing pigs (PIC TR4 × 1050; initially 60 ± 4.7 kg) were used in a 58 days growth assay to determine the effects of an abrupt change in diet form from meal to pelleted and pelleted to meal diets on growth performance and carcass measurements. The experiment was designed as a randomized complete block design with 5 pigs per pen and 10 pens per treatment. Diets were fed in 2 phases, day 0–36 and day 36–58 for phase 1 and 2, respectively. Treatments were meal to meal, meal to pelleted, pelleted to meal, and pelleted to pelleted diets for Phases 1 and 2 of the experiment, respectively. For Phase 1 (day 0–36), pigs fed the mean of the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the mean of the meal diet. For Phase 2 (day 36–58), pigs fed the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diets. Pigs fed the pelleted diet from day 0 to 58 had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet from day 0 to 58. For day 0–58, pigs fed the pelleted diet for either Phase 1 or 2, but not both, tended to have decreased (P < 0.11) ADG and G:F compared to those fed the pelleted diet for the entire experiment. Pigs fed the meal then pelleted diet did not differ (P > 0.27) in performance compared to those fed the pelleted then meal diet. No differences (P > 0.19) were observed in dressing percentage, fat thickness, loin depth, or percentage fat free lean index. In conclusion, pigs fed the pelleted diet the entire experiment had increased ADG compared to pigs fed the meal diet. Pigs fed the pelleted diet had the greatest G:F, pigs fed meal the worst, and pigs fed pellets for only part of the grow-finish phase fell between the other treatments. Published by Elsevier B.V.
1. Introduction Feed processing technologies can be used to maximize feed utilization. Pelleting swine diets has been shown to improve efficiency of gain (Wondra et al., 1995a). However, adding the necessary infrastructure to allow for pelleting a diet consist of a high initial cost, along with decreasing production rates, and increasing energy usage, which leads to higher feed cost for the producer. This could be a potential problem with an increase in pork and chicken demands. Not being able to achieve adequate production rates could be a problem for some feed manufactures. Therefore, swine producers may not be able to feed pelleted diets throughout the entire growing-finishing phase. Data has not been reported on the effects of switching from meal to pelleted diets and vice versa and if feeding pelleted diets throughout the entire
Abbreviations: ADG, average daily gain; ADFI, average daily feed intake; G:F, g of gain per kg of feed. ∗ Corresponding author. Current address: Department of Animal Science, Texas A&M University, College Station, TX 77840, USA. E-mail address: [email protected] (C.B. Paulk). http://dx.doi.org/10.1016/j.anifeedsci.2015.10.017 0377-8401/Published by Elsevier B.V.
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133
Table 1 Composition of diets (as-fed basis). Item (g/kg)
Phase 1a
Phase 2b
Corn Soybean meal Choice white grease l-Lysine HCl dl-Methionine l-Threonine l-Tryptophan Monocalcium phosphate Limestone Salt Vitamin premixc Mineral premixd Folic acide Antibioticf
792.5 171.5 10.0 3.4 0.70 1.17 0.23 7.2 9.1 2.5 0.8 0.4 0.01 0.5
847.0 119.0 10.0 3.5 0.48 1.10 0.37 5.4 8.9 2.5 0.8 0.4 0.01 0.5
Calculated analysis (g/kg) Standardized ileal digestible lysine Calcium Phosphorus
8.8 5.5 4.9
7.6 5.0 4.3
a
Diets fed in meal or pelleted form from day 0 to 36. Diets fed in meal or pelleted form from day 36 to 58. c Supplied (per kilogram of diet) 1764 IU vitamin A from vitamin A acetate, 265 IU vitamin D from vitamin D3 , 7.05 IU vitamin E d-␣-tocophorol acetate, 0.71 mg vitamin K from menadione nicotinamide bisulfite, 6.2 g vitamin B12 from cyanocobalamin, 7.9 mg niacin from niacinamide, 4.4 mg pantothenic acid from calcium pantothenate, and 1.32 mg riboflavin from crystalline riboflavin. d Provided (per kilogram of diet) 39.7 mg manganese from manganese oxide, 165 mg iron from iron sulfate, 165 mg zinc from zinc oxide, 16.5 mg copper from copper sulfate, 0.298 mg iodine from calcium iodate, and 0.298 mg selenium from sodium selenite. e Provided (per kilogram of diet) 1 mg folic acid. f Tylan 40 (Elanco Animal Health, Greenfield, IN) provided 44 mg of tylosin as tylosin phosphate per kg of complete diet. For control of swine dysentery associated with Brachyspira hyodysenteriae, and for control of porcine proliferative enteropathies (ileitis) associated with Lawsonia intracellularis. b
grower and finisher stage is necessary to achieve performance benefits. Therefore, our objective was to determine the effects of abrupt changes between meal and pelleted diets on growth performance of finishing pigs. 2. Materials and methods All experimental procedures were approved by the Institutional Animal Care and Use Committee at Kansas State University. 2.1. Experimental design All feed processing was completed at a commercial feed mill (Key Feeds, Clay Center, KS). For all diets, corn was milled through a hammer mill (Jacobseen P24209 Series 2) with a screen size of 3.18 mm (full circle screen). The ASAE (1983) standard method was used to determine the particle size of milled corn. Tyler sieves, with numbers 6, 8, 10, 14, 20, 28, 35, 48, 65, 100, 150, 200, 270, and a pan, were used for particle size determination. A Ro-Tap® shaker (W. S. Tyler, Mentor, OH) was used to sift the 100 g samples for 10 min. A geometric mean particle size (dgw) was calculated by measuring the amount of ground grain remaining on each screen. The pelleted diets were pelleted in a 125 horsepower pellet mill (Century, California Pellet Mill, San Francisco) and the die had 4.8 mm openings. Pellets were analyzed for pellet durability index (ASAE, 1987) and modified pellet durability index by altering the procedure by adding 5 13-mm hexagonal nuts prior to tumbling. A total of 200 finishing pigs (TR4 × PIC 1050; Hendersonville, TN) with an average initial body weight of 60 ± 4.7 kg were used in a 58-day growth assay. The pigs were weighed prior to the experiment and blocked by body weight. Pigs were then assigned to concrete slatted flooring pens (3 barrows and 2 gilts placed in each pen) that were 2.44 m × 1.53 m. Each pen consisted of a nipple waterer and single-hole self-feeder allowing ad libitum consumption of feed and water. There were a total of 40 pens, with 5 pigs per pen 10 pens per treatment. All diets (Table 1) were the same formulation fed in either meal or pellet form. Diets were fed in 2 phases, day 0–36 and day 36–58 for phase 1 and 2, respectively. All nutrients met or exceeded NRC recommendations (NRC, 1998). Treatments were meal to meal, meal to pelleted, pelleted to meal, and pelleted to pelleted diets for phases 1 and 2 of the experiment. Pigs and feeders were weighed on day 0, 36, and 58 to determine ADG, ADFI, and G:F. Feed wastage was not prevented in any manner; therefore, ADFI is a measure of feed disappearance. On day 58 of the experiment, pigs (average body weight of 128 ± 2.37 kg) were tattooed and shipped to a commercial abattoir (Farmland Foods, Inc.; Crete, NE) for slaughter the following morning. Measurements were acquired
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immediately after slaughter for hot carcass weight, loin depth, and 10th rib fat thickness (SFK Technology A/S model S 82; Herlev, Denmark). Dressing was calculated as hot carcass weight divided by preshipping live weight. Carcass fat free lean percentage was calculated with fat free lean index as a percentage of hot carcass weight. Fat free lean index was calculated using the equation suggested by the National Pork Producers Council (NPPC, 2001). 2.2. Statistical analyses Data was analyzed as a randomized complete block design using the MIXED procedure of SAS (v9.1; SAS Inst. Inc., Cary, NC) with block representing initial weight and pen location within a single blocking criterion and pen as the experimental unit. Dietary treatment was included in the model statement as the fixed effect. For day 0–36 and 36–58 the main effect of meal vs. pelleted diets were compared. For the overall experiment (day 0–58), orthogonal contrasts were used to separate treatment means with comparisons of: (1) control vs. pelleted treatments fed from day 0 to 58; (2) treatments pelleted for the entire experiment vs. treatments pelleted for either phase 1 or 2 but not both; (3) treatments fed in pelleted form for phase 1 and meal form for phase 2 vs. treatments fed in meal form for phase 1 and pelleted form for phase 2. 3. Results 3.1. Feed processing characteristics For phase 1 and phase 2 the pelleted diets resulted in pellet durability indexes of 86 and 87% and modified pellet durability indexes of 80 and 77%, respectively. The average mean particle size for ground corn was 433 m. 3.2. Growth performance For day 0–36, pigs fed the mean of the pelleted diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet (Table 2). For day 36–58, pigs fed the pelleted diet had increased (P < 0.01) ADG and G:F compared to those fed the meal diet. Overall (day 0–58), pigs fed the pelleted for the entire experiment diet had increased (P < 0.01) ADG and G:F compared to pigs fed the meal diet. For day 0–58, pigs fed the pelleted diet for either Phase 1 or 2, but not both, tended to have decreased (P < 0.11) ADG and G:F compared to those fed the pelleted diet for the entire experiment. Pigs fed the meal then pelleted diet did not differ (P > 0.27) in performance compared to those fed the pelleted then meal diet. There was a tendency for pigs fed the meal diet for the entire experiment to have a decreased (P < 0.10) final body weight and hot carcass weight compared to those fed the pelleted diet for the entire experiment. No differences in treatments (P > 0.15) were observed in dressing, fat thickness, loin depth or percentage fat free lean index. Table 2 Effects of abrupt change between meal and pelleted diets on growth performance in finishing pigsa Item
Day 0–36 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Day 36–58 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Day 0–58 Average daily gain (g) Average daily feed intake (kg) Gain:feed (g/kg) Final body weight (kg) Hot carcass weight (kg) Dressingc Backfat thickness (mm) Loin depth (mm) Fat-free lean indexd (%)
Meal to meal
Meal to pellet
Pellet to meal
Pellet to pellet
SE
Probabilityb,c (P<) 1
2
3
1115 2.88 388
1132 2.87 397
1170 2.76 423
1164 2.76 423
29.2 0.090 5.9
0.01 0.17 0.001
– – –
– – –
1161 3.53 330
1231 3.46 358
1118 3.42 327
1239 3.50 355
25.2 0.094 6.3
0.01 0.92 0.001
– – –
– – –
1132 3.12 363
1170 3.09 380
1150 3.01 382
1192 3.04 393
24.2 0.088 7.1
0.01 0.28 0.001
0.11 0.83 0.06
0.39 0.27 0.85
126.0 94.1 0.746 18.7 66.5 52.2
128.3 95.3 0.743 19.8 67.3 51.6
127.2 95.0 0.743 19.6 68.2 51.7
129.0 95.9 0.744 19.8 67.5 51.6
2.37 1.71 0.0025 1.00 0.84 0.61
0.10 0.10 0.71 0.19 0.40 0.26
0.35 0.41 0.61 0.83 0.84 0.83
0.49 0.78 0.97 0.82 0.46 0.86
A total of 200 pigs (average initial BW of 60 ± 4.7 kg) were used in 58 days growth assay The contrast statement for Phases 1 and 2 compared meal vs. pelleted diets within the respective phase. Contrast statements for the overall experiment were: (1) meal vs. pelleted diet for the entire experiment; (2) Pelleted diets fed for entire experiment vs. pelleted diets fed for only part of experiment; (3) Meal to pellet vs. pellet to meal c Dressing = hot carcass weight divided by preshipping live weight. d Fat-free lean index, calculated using NPPC (2001) equation, as a percentage of hot carcass weight. a
b
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4. Discussion The experiment reported herein observed a 5 and 8% improvement in ADG and G:F when pigs were fed pelleted diets compared to those fed meal diets, respectively. This is in agreement with previous research that reported improvements in ADG and G:F when pelleting swine diets (Baird, 1973; Chamberlain et al., 1967; Hanke et al., 1972; Wondra et al., 1995a). There are a number of theories that try and explain the mechanism behind the improvement in growth performance do to pelleting diets. Skoch et al. (1983) proposed the idea that pelleting increased the bulk density of diets and reduced dustiness, therefore, making the diets more palatable. However, this is not supported by the inconsistencies observed with feed intake in pelleting experiments. Jensen and Becker (1965) observed pelleted diets having improved carbohydrate fraction susceptibility to in vitro enzymatic digestion compared to meal diets. Moreover, Wondra et al. (1995a,b) reported improvements in DM, N, and gross energy apparent total tract digestibilities due to pelleting. Similarly, Le Gall et al. (2009) demonstrated improvements in OM and energy apparent total tract digestibility with pelleting. However, the authors did not observe improvements in fecal apparent total tract N digestibility with pelleting. Stein and Bohlke (2007) also demonstrated no improvements in N and amino acid digestibility with pelleting. Therefore, a portion of the improvement in performance may be associated with improvements in energy digestibility. Although, stomach ulceration and keratinization were not measured in the study reported herein, it is also important to consider what processing factors influence gut morphology and how to maximize efficiency without inducing ulceration. It was previously determined that fine grinding can have negative effects on stomach morphology (Mahan et al., 1966; Maxwell et al., 1970; Ayles et al., 1996), but it has also been reported that pelleting can also increase the incidences of ulceration of the pars esophageal region of the stomach (Millet et al., 2012; Paulk et al., 2015). It has been hypothesized that this is due to the increased fluidity of stomach contents, which results in more mixing of stomach contents. Mixing of the fluid stomach content allows for continuous exposure of the unprotected mucosa of the esophageal region to pepsin and digestive acids (Reimann et al., 1968; Maxwell et al., 1970, 1972). Although pelleting diet may negatively impact stomach morphology, there were no mortalities during the experiment reported herein. Abrupt changes between meal and pelleted diets did not result in overall negative or positive effects on growth performance of finishing pigs. Pigs fed pelleted diets for half and meal diets for the other half of the experiment had performance intermediate to those fed the pelleted or meal diet for the entire experiment. 5. Conclusion In conclusion, pigs fed the pelleted diet the entire experiment had increased ADG compared to pigs fed the meal diet. Pigs fed the pelleted diet had the greatest G:F, pigs fed meal the worst, and pigs fed pellets for only part of the grow-finish phase fell between the other treatments. Conflict of interest The authors declare that there are no conflicts of interest. References ASAE, 1983. Method of determining and expressing fineness of feed materials by sieving. In: ASAE Standard S319, Agricultural Engineers Yearbook of Standards. American Society of Agricultural Engineers, pp. 325. ASAE, 1987. Wafers, pellets, and crumbles – definitions and methods for determining density, durability, and moisture content. In: ASAE Standard S269.3, Agricultural Engineers Yearbook of Standards. 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