- Email: [email protected]
Phase feeding in a big-bird production scenario: Effect on growth performance, yield, and fillet dimension
PRODUCTION, MODELING, AND EDUCATION Phase feeding in a big-bird production scenario: Effect on growth performance, yield, and fillet dimension V. B. Brewer,* C. M. Owens,*1 and J. L. Emmert† *Department of Poultry Science, University of Arkansas, Fayetteville 72701; and †Department of Animal Sciences, University of Illinois, Urbana-Champaign 61801 that matched the predicted PF requirements over 2-d intervals. Weight gain, feed intake, and feed efficiency were calculated through d 58. Birds were commercially processed at 59, 61, or 63 d; yield and fillet dimensions were measured. Phase feeding did not effect weight gain or feed intake of broilers during the overall growth period (17–58 d). For most strains, PF did not effect final BW, yield, or fillet dimensions. However, strain and sex had greater effects on growth performance, yields, and fillet dimensions. Strains B and D had greater breast yield than strains A and C. Reduced feed costs ($0.01 to $0.04 per kilogram of gain, depending on strain) were observed for all strains with PF for the overall growth period (17–58 d). Therefore, potential savings on feed costs are possible for all strains used in this study with the incorporation of the PF regimen.
Key words: phase feeding, strain, broiler, yield 2012 Poultry Science 91:1256–1261 http://dx.doi.org/10.3382/ps.2011-01707
INTRODUCTION Commercial broiler production is a dynamic and ever-changing industry, and poultry nutritionists and researchers are not exempt from this change. Many recommendations have been made for the nutrient requirements of broilers at a wide variety of ages, as well a variety of feeding regimens to best meet these needs. The NRC (1994) has a single set of recommendations for both male and female broilers; however, these recommendations are rarely used in a commercial setting because these recommendations over-feed valuable nutrients throughout the life of the broiler. Less of the valuable nutrients in broiler diets are needed for the maintenance of muscle than for the accretion of muscle. Because of this, it is common practice in the poultry industry for commercial nutritionists to formulate as many as 6 diets for the growth of one flock to accurately meet nutritional needs. This may negatively affect ©2012 Poultry Science Association Inc. Received June 27, 2011. Accepted January 16, 2012. 1 Corresponding author: [email protected]
the meat quality of the modern high-yielding broiler, which accrue much of their muscle mass beyond 40 d of age and, therefore, actually need a more nutrient-dense diet in the later stages of grow out. However, it does reduce the cost of production by substantially reducing feed costs compared with the NRC recommendations. Phase feeding (PF) describes the philosophy of feeding broilers over shorter periods of time with the goal of precisely feeding broilers to meet, but not exceed, their amino acid requirements. Emmert and Baker (1997) developed a series of regression equations that are the basis of PF. Using these equations, digestible amino acid content of a diet is expressed as a function of age. Therefore, amino acid requirements for broilers can be predicted at a wide variety of ages, and excess dietary amino acids and CP can be eliminated. Phase feeding has been used switching diets weekly (Pope and Emmert, 2001) and every other day (Pope et al., 2002; Brewer et al., 2006b). The nature of the PF regimen and the regression equations used to formulate the diets allow for a variety of feeding intervals to be used. In previous research, PF has maintained growth and parts yields while improving feed efficiency and uni-
1256
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
ABSTRACT Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains and sex has not been assessed. An experiment was conducted using 4 commercial broiler strains grown up to 63 d of age (n = 1,440), comparing a PF approach to an industry-type diet. At d 17, birds began either the industry or PF regimen. The industry regimen consisted of average industry nutrient levels with periods from 17 to 32 d, 32 to 40 d, 40 to 49 d, and 49 d to the end of trial. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient density diets were blended to produce rations containing amino acid levels
1257
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS Table 1. Percentage of composition of basal diets, as-fed basis Industry Item Ingredient Corn Soybean meal Poultry fat Vitamin mineral mix Dicalcium PO4 Limestone NaCl dl-Methionine l-Threonine Composition ME,2 kcal/kg CP, % Total Lys, % Total Met, % Total Cys, % Total Thr, %
17–32 d
32–40 d
40–49 d
49–59 d
65.6 28.0 2.50 0.30 1.55 1.25 0.40 0.246 0.070 3,100 19.3 1.10 0.52 0.31 0.78
69.1 24.5 2.66 0.30 1.32 1.25 0.35 0.264 0.043 3,150 17.9 1.00 0.39 0.43 0.70
69.8 23.5 3.25 0.30 1.25 1.10 0.35 0.222 0.040 3,200 17.5 0.97 0.36 0.41 0.68
71.2 22.4 3.00 0.30 1.25 1.10 0.35 0.222 0.040 3,200 17.1 0.94 0.47 0.29 0.65
PF HN1
PF LN1
17–19 d
57–59 d
62.0 31.2 2.96 0.30 1.50 1.25 0.40 0.216 0.039 3,100 20.5 1.19 0.41 0.44 0.80
79.2 16.6 1.03 0.30 1.20 1.10 0.35 0.072 0.024 3,150 14.9 0.76 0.28 0.30 0.56
formity, when compared with both NRC and a typical industry-type feeding regimen (Warren and Emmert, 2000; Pope and Emmert, 2001; Pope et al., 2002; Brewer et al., 2006b). Phase feeding has also been shown to reduce nitrogen excretion and improve broiler performance during periods of heat stress (Pope and Emmert, 2001). However, previous research with PF has always been conducted with a male breeder by-product of one commercial strain. There are many strains available for broiler production, and much research has been conducted on the performance of various broiler strains. Some strains have improved growth and parts yield, especially breast yield, compared with others (Peak et al., 2000; Bilgili et al., 2006; Mehaffey et al., 2006). Also, typically male and female broilers are reared together. Research conducted where both genders were evaluated has indicated differences in the growth and in the yield of male and female broilers (Young et al., 2001). Therefore, the objective of this study was to evaluate the effect of PF, strain, and sex on growth performance, feed efficiency, parts yield, fillet dimension, and uniformity.
MATERIALS AND METHODS All procedures were approved by the University of Arkansas Institutional Animal Care and Use Committee. For this experiment, 4 commercial strains commonly used in industry were reared up to 63 d to simulate a big-bird production scenario. The strains were bred to be high or moderate breast-yielding broilers, and all strains are used in typical industry big-bird programs. A factorial arrangement of treatments was used with 4 strains and 2 diets, resulting in 8 experimental treatments; treatments were replicated 6 times (n = 1,440 total). Birds, 15 male and 15 female chicks per pen, were reared in floor pens. On d 3, all chicks were
weighed and allotted to pens so that initial pen weight was uniform; wing bands were used for individual identification throughout the trial period. Prior to d 3, birds were held in groups according to strain and sex. From 0 to 17 d, all treatments were fed a common starter diet. At d 17, the trial period began and birds were fed either an industry-type diet or a PF regimen (Table 1). Treatments were held on a 23L:1D photoperiod and both water and experimental diets were provided ad libitum.
Phase-Feeding Regimen Phase-feeding regimens were based on regression equations from Emmert and Baker (1997) and were used to predict every-other-day amino acid requirements as follows: digestible Lys, y = 1.22 – 0.0095x; digestible Met and Cys, y = (0.88 – 0.0063x)/2; and digestible Thr, y = 0.8 – 0.0053x, where y = digestible amino acid level, and x = midpoint (day) of the desired age range. For this regimen, a high-nutrient (HN) diet was formulated for predicted amino acid requirements for 17 to 19 d, and the low-nutrient (LN) diet was formulated for predicted amino acid requirements for 58 to 60 d (Table 1). The HN and LN diets were blended to produce the PF diets throughout the trial period; there were 22 intermittent blends of the formulated HN and LN diets. The industry regimen was based on averaged industry nutrient levels, and periods were as follows: grower (17–32 d), finisher 1 (32–40 d), finisher 2 (40–49 d), and withdrawal (49 to end of trial). To assess growth performance, birds were individually weighed, and feed was weighed at d 3, 17, 32, 40, and 49. On d 58, one day before processing, group weights were measured for feed intake and feed efficiency (FE; gain:feed) data, and individual live weights were measured at the dock before processing. Weight gain, feed intake, and FE were determined through d 58. Mortal-
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
1Phase feeding (PF) diets were formulated to contain Lys, sulfur amino acid, and Thr levels predicted by linear regression equations for 17- to 19-dold [PF high nutrient (HN)] or 57- to 59-d-old [PF low nutrient (LN)] broilers. Experimental diets were produced by blending PF HN and PF LN diets invariable quantities (see Materials and Methods). 2ME data represent calculated values; all other data represent analyzed values.
1258
1,031b 534ab 575b 588ab 2,728ab 1,659b 998a 1,389bc 1,551abc 5,593ab 622ab 536ab 411ab 382ab 488ab 3,170bc 1,031b 516bc 563b 529abc 2,641ab 1,663b 969a 1,390bc 1,306cd 5,325b 621ab 534abc 405ab 402a 495a 3,096cd 1,105a 524bc 489d 535abc 2,657ab 1,757a 1,021a 1,310c 1,391bcd 5,475b 630a 513bc 372c 390ab 484ab 3,138bcd within a row lacking a common superscript differ (P < 0.05). = phase feeding. 2Data combined across sex for strain and feeding regimen comparison. 3Data combined across 3 processing days: d 59, 61, and 63. 1PF
a–eValues
Final BW2,3 (g)
Feed efficiency2 (G:F, g:kg)
Feed intake2 (g/chick)
17–32 32–40 40–49 49–58 17–58 17–32 32–40 40–49 49–58 17–58 17–32 32–40 40–49 49–58 17–58 Weight gain2 (g/chick)
d d d d d d d d d d d d d d d
1,006bc 509c 543bc 561abc 2,619ab 1,652b 986a 1,413abc 1,583bc 5,629ab 609bc 515bc 385bcd 360ab 466c 3,119cd
996c 516bc 498d 478bc 2,488b 1,608b 994a 1,316c 1,461bcd 5,376b 619ab 519bc 379cd 329b 463c 2,997e
992c 557a 623a 641a 2,811a 1,611b 1,005a 1,520a 1,802a 5,933a 613ab 554a 411ab 357ab 475bc 3,320a
991c 550a 618a 614ab 2,775a 1,587b 1,030a 1,468ab 1,625ab 5,706ab 625ab 534abc 422a 382ab 485ab 3,231ab
1,078a 457d 516cd 456c 2,508b 1,821a 921a 1,294c 1,197d 5,229b 593c 496c 398abc 379ab 479abc 3,035de
Industry PF Industry
PF
Strain C Strain B
PF1 Industry Period Item
Phase feeding as a main effect significantly affected weight gain during the 32 to 40 d and 40 to 49 d growth periods (P = 0.0003 and P = 0.0333, respectively); however, there was a significant interaction between strain and feeding regimen for those periods. Therefore, the interactions for growth parameters are presented in Table 2. Phase feeding did not affect weight gain of broilers, with the exception of strain A from 40 to 49 d and strain C from 32 to 40 d. However, the effect of PF in these 2 instances was different. Weight gain was increased with strain C due to PF and was decreased with strain A due to PF in the before-mentioned periods. For the overall growth period (17–58 d), there was no significant effect of PF on weight gain for any strain (P = 0.7716). Furthermore, there was no effect of PF on feed intake over any growth period, including the overall growth period (P = 0.9510). Strain had a greater effect on feed intake; however, it varied depending on feeding regimen and growth period. Also, there was no difference in FE between industry and PF
Strain A
RESULTS AND DISCUSSION
Table 2. Effect of strain and feeding regimen on weight gain, feed intake, feed efficiency, and BW
The experiment was analyzed as a randomized complete block design with a factorial arrangement of treatments (strain, diet, sex). For weight gain, BW, and yields, and individual bird was the experimental unit; for feed intake and FE, pen was the experimental unit. The GLM procedure of SAS was used to conduct ANOVA on all data. For feed data differences among treatments, means were established using the least significant difference multiple comparison procedure. For growth, yield and fillet dimension data differences were established using Duncan’s multiple-range test. Differences were considered significant at P < 0.05. In this study, deboning hour did not significantly affect yield; therefore, yield data was pooled across all deboning hours. Debone hour did significantly affect fillet dimension; therefore, only the data of fillets deboned at 6 h PM is presented.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
Statistical Analysis
Industry
Strain D
PF
Pooled SEM
ity and culls were accounted for daily and all calculations were adjusted accordingly. Mortality was approximately 6% for the overall grow-out period (through 58 d). Following a 10-h feed-withdrawal period, birds were processed at the university pilot poultry processing plant using commercial methods (Mehaffey et al., 2006). Briefly, birds were stunned, exsanguinated, scalded, picked, and eviscerated on an in-line commercial-type system, followed by chilling to 4°C internal temperature. Processing took place over 3 d (d 59, 61, 63), 2 replicates per day, and carcasses were deboned at 2, 4, and 6 h postmortem (PM) and parts weighed to determine yields. Fillet dimensions were measured at 24 h PM on fillets deboned at 6 h PM, according to procedures described by Mehaffey et al. (2006) for an additional assessment of growth performance.
4.0 3.1 4.5 15.5 32.2 14.3 12.0 17.7 42.4 67.6 2.6 4.6 4.1 7.6 2.7 13.2
Brewer et al.
1259
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS Table 3. Body weights of males and females from 4 high-yielding broiler strains Strain A BW1 (g)
Female
Day 3 Day 17 Day 32 Day 40 Day 49 Final BW2
77d 472d 1,411d 1,883e 2,355e 2,870e
Strain B
Male 78d 503c 1,565c 2,116c 2,678c 3,263c
Female
Male
74e 447e 1,385d 1,887e 2,459d 3,031d
Strain C Female
79d 492c 1,542c 2,145bc 2,837a 3,561a
Male
87b 522b 1,537c 2,005d 2,485d 2,947de
Strain D Female
93a 572a 1,733a 2,245a 2,761b 3,247c
83c 466d 1,411d 1,875e 2,394e 2,879e
Pooled SEM
Male 77d 490c 1,608b 2,185b 2,809ab 3,411b
0.3 2.0 5.4 7.1 9.1 13.2
a–eValues
within a row lacking a common superscript differ (P < 0.05). combined across feeding regimen for strain and sex comparison. 2Data combined across 3 processing days: d 59, 61, and 63. 1Data
accelerated growth during the later periods, after 40 d, weighing more at the time of processing than strain C. By d 49, strain B males were significantly heavier than strains A and C, with no difference between strain B and D males. For the females, strain C also had accelerated growth early, by d 17 through d 40, compared with other strains. However, although strain C was larger than strain A at d 17, 32, 40, and 49, there was no difference in BW at processing for these 2 strains, suggesting strain C had a slower growth rate toward the end of grow out. Similar to the males, females of strain B had accelerated growth beyond d 40 and were similar in BW to females of strain C but significantly heavier than females of strains A and D at d 49 and at processing. Differences in growth patterns among the strains can be expected because they have varying selection parameters in the breeding programs. Males weighed significantly more than females at all days measured during grow out. As expected, especially with the overall length of grow out, these differences between sexes became larger as the grow-out period increased. Overall, these growth data for strain indicate that strains B and D are more suited to longer grow outs because they had significantly greater live weights at processing (i.e., 60 d). Carcass and breast yield were assessed to determine processing performance as a result of dietary regimen changes. Phase feeding did not affect carcass yield in any strain, as indicated by no significant differences in ready-to-cook yield between industry and PF dietary treatments (Table 4). Generally, PF did not affect breast yield in strains B, C, and D, as indicated by no
Table 4. Yields of broilers from 4 high-yielding strains fed industry or phase-feeding (PF) diets Strain A Item RTC yield1,2,3 (%) Fillet yield1,2,4 (%) Tender yield1,2,4 (%) Total breast1,2,4 (%) a–cValues
Strain B
Industry
PF
78.4 22.5b 5.65a 28.1b
78.1 21.8c 5.48b 27.4c
Strain C
Industry
PF
78.6 23.5a 5.66a 29.1a
78.7 23.4a 5.58ab 29.0a
within a row lacking a common superscript differ (P < 0.05). averaged over 3 processing days: d 59, 61, and 63. 2Data averaged over 3 debone times: 2, 4, and 6 h postmortem. 3Ready-to-cook (RTC) yield expressed as percentage of live weight. 4Parts yield expressed as a percent of RTC weight. 1Data
Strain D
Industry
PF
78.7 22.2bc 5.57ab 27.8b
79.1 22.1bc 5.49b 27.6bc
Industry
PF
78.9 23.6a 5.68a 29.3a
78.6 23.5a 5.68a 29.2a
Pooled SEM
0.09 0.07 0.03 0.07
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
regimens for the overall period (P = 0.6522) or other periods, with the exception of one instance where strain C had improved FE with the PF regimen during the 17 to 32 d period. As a main effect, feeding regimen did not significantly affect BW at processing (P = 0.5660); however, there was a significant strain by feeding regimen interaction (P = 0.0021). Strain A had decreased BW at processing with PF, whereas strain C had slightly increased BW with the PF regimen at the time of processing (Table 2). The lower gains for strain A over growth periods beyond 40 d, taken cumulatively, likely resulted in the decreased final BW for this strain. These data could indicate that strain A requires a higher level of amino acid density in the diet. Body weights of the strains over the grow-out period are presented in Table 3. Significant differences in BW among strains were observed as early as 3 d. Strain C had the heaviest chicks at 3 d, followed by chicks from the other strains. For males, chicks did not differ in weight between strains A, B, and D. However, for females, 3-d-old chicks from strain C chicks were the heaviest, followed by chicks from strains D, A, and B, which all differed (P < 0.05) from each other. Broilers from strain C had consistently heavier BW at all days measured from 17 to 40 d, compared with other strains for both males and females. All strains varied in growth pattern form 17 to 58 d. For example, strain C males gained significantly more during the early growth periods and then decreased compared with other strains after 40 d. Strains B and D males gained slower during the beginning growth periods, up to 32 d, and then had
1260
Brewer et al.
Table 5. Fillet dimensions of broiler breast fillets from 4 high-yielding strains fed industry or phase-feeding (PF) diets Strain A
Strain B
Item
Industry
PF
Fillet weight1 (g) Length1 (cm) Width1 (cm) Cranial thickness1 (cm) Caudal thickness1 (cm)
546c 19.2b 9.79ab 2.75cde 0.92bcd
504d 18.7c 9.59b 2.62e 0.85d
a–eValues
Strain C
Industry
PF
612a 19.0bc 10.0a 3.01ab 1.04ab
594a 19.0bc 9.81ab 3.15a 1.08a
Strain D
Industry
PF
522d 19.5ab 9.72b 2.69cde 1.02abc
507d 19.4ab 9.88ab 2.66de 0.89cd
Industry
PF
574b 19.4ab 9.79ab 2.88bc 1.09a
582b 19.6a 9.76ab 2.85bcd 0.98abcd
Pooled SEM
3.25 0.20 0.14 0.06 0.03
within a row lacking a common superscript differ (P < 0.05). over 3 processing days: d 59, 61, and 63; data of fillets deboned at 6 h only.
1Averaged
in dollars per kilogram of breast meat, as previously reported (Pope et al., 2002; Brewer et al., 2006a,b). Feed savings with PF result from more accurately targeting amino acid requirements of broilers and not overfeeding expensive nutrients. As described by Pope et al. (2002), formulation of PF diets over 2-d intervals is simply not feasible, especially when considering a commercial industry spectrum and addition of cost of feed delivery. However, the PF regimen used in this study and also by Pope et al. (2002) had only 2 diets formulated, and these 2 diets were blended to produce the PF rations. For this to work on a commercial level the HN and LN diets would be delivered to the farm and the diets would be blended using feed equipment on the farm (Warren and Emmert, 2000). In this study, PF feed costs were significantly lower for strain C compared with industry during the grower (17–32 d) period; there were no significant differences due to feeding regimen for strains A, B, and D during that period (Table 6). There were no significant differences in feed cost due to feeding regimen during finisher 1 (32–40 d), finisher 2 (40–49 d), or withdrawal (49–58 d) for any strain. When evaluating costs for the overall period, PF cost significantly less in dollars per kilogram of gain ($0.04 difference) in strain B but not in other strains. However, for all the strains used in this study, the cost difference on a per kilogram of gain basis ranged from $0.01 to $0.04 in all strains, and though not statistically significant, these results are similar to previous research where PF has resulted in a reduction in feed cost between PF and NRC regimen of $0.01/kg of gain and $0.06/kg of breast meat (Pope et al., 2002, 2004). There was some variation among strains in feed cost for birds on the industry diet. Strain D had a significantly lower overall (17–58 d) cost (dollars/kg of gain) compared with strain A, whereas strains B and C were intermediate. When considering feed costs for dollars per kilogram of breast meat, strain D was significantly less expensive to produce compared with strains A and C, but similar to strain B. These differences in costs associated with growth could be attributed to the selection characteristics used in their breeding programs. These decreases in production cost related to feed, not significant in all cases, could seem trivial on a per kilogram basis. However, the large production volume of the poultry industry converts these seemingly small reductions in production costs into substantial savings. Though savings are variable among the strains, PF
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
significant difference in fillet, tender, or total breast yield between industry and PF. With strain A, PF resulted in significantly lower fillet, tender, and total breast yield. This could be attributed to an increased nutritional need for strain A compared with the other strains evaluated. In previous research, a decrease in breast yield was observed when PF amino acid levels were decreased by 10% (PF 10) though normal PF diets had no negative effect on yield (Pope et al., 2002; Brewer et al., 2006b). Therefore, if a broiler had increased nutritional needs in this study, it is possible that breast yield would be reduced. Strain affected breast yields also (Table 4). Strains that showed accelerated growth through the final periods (e.g., strains B and D) are also the strains that had significantly greater breast yield (fillet and total breast). There was no significant difference in breast yield (fillet and total breast) for strains A and C, and they both yielded significantly less than strains B and D, which were similar. These results could be attributed to the possible differences in breeding selection programs for the various strains. Fillet dimensions were also measured and are presented in Table 5. With the exception of strain A, fillet dimensions were not affected by PF, as indicated by no significant difference in the length, width, and height of fillets between industry and PF treatments. In strain A, PF treatments had significantly lower fillet weight and length compared with industry feeding treatments, while no other dimensions were affected. Therefore, it appears that the decrease in yield observed for strain A can be attributed to the decrease in fillet length with the PF treatments. However, Lubritz (1997) suggested that fillet thickness has 7 times more impact on fillet weight than length or width. So, perhaps it was a combination of decreased fillet length and thickness (0.13 cm numerical difference in cranial thickness, though not significant) that were associated with a decrease in fillet weight for the PF regimen with strain A. Strain also affected fillet dimension (Table 5). Strains C and D had significantly longer fillets than strains A and B, with no difference in width for any strains. Increased fillet yield that was reported with strains B and D can be attributed to the thickness of the fillet. At both the cranial and caudal region, the fillets for these strains were significantly thicker than strains A and C. The main advantage of the PF regimen compared with a typical industry regimen is the decrease in cost of feed not only in dollars per kilogram of gain but also
within a row lacking a common superscript differ (P < 0.05). difference = industry feed costs – PF feed costs in dollars/kg. Values in parentheses denote that PF costs more than industry. 2Feed cost per bird was first determined by multiplying the amount of feed consumed by the dietary cost, which was calculated based on values of $0.2425/kg for corn, $0.3968/kg for soybean meal, $1.1908/kg for l-lysine HCl, $3.3069/kg for dl-methionine, and $4.1887/kg for l-threonine. Feed cost per bird was then divided by the weight gain per bird. 3Calculated by dividing the feed cost per bird by the amount of breast meat (fillet and tenders) per carcass. 1Cost
$/kg of breast3
a–dValues
0.00 0.02 0.04 (0.01) 0.01 (0.01) 0.49bc 0.55b 0.70bc 0.75 0.60d 2.27b 0.49bc 0.57ab 0.74abc 0.74 0.61bcd 2.26b 0.03 0.03 (0.03) 0.05 0.02 0.01 0.49c 0.58ab 0.78a 0.75 0.61cd 2.40a 17–32 32–40 40–49 49–58 17–58 $/kg of gain2
Cost
Age
d d d d d
0.51ab 0.59ab 0.78a 0.83 0.65a 2.48a
0.49bc 0.57ab 0.76ab 0.85 0.63abc 2.48a
0.02 0.02 0.02 (0.02) 0.02 0.00
0.50bc 0.54b 0.73abc 0.83 0.64ab 2.37ab
0.49bc 0.56b 0.68bc 0.74 0.60d 2.27b
0.01 (0.02) 0.05 0.08 0.04 0.10
0.52a 0.61a 0.75abc 0.80 0.63abc 2.41a
PF Ind. Cost difference PF Ind. Cost difference PF Ind.
PF
Cost difference1
Ind.
Strain B Strain A
Table 6. Feed costs associated with industry (Ind.) and phase-feeding (PF) diets for 4 high-yielding broiler strains
1261
could still potentially save companies billions of dollars in feed costs.
Conclusion In conclusion, PF did not negatively affect weight gain or feed efficiency over the overall grow-out period (17–58 d). Furthermore, yields (ready to cook, fillet, and total breast) were not negatively affected by PF in most strains. Strain and sex had significant effects on growth performance, yield, and fillet dimensions. Results suggest that PF does not negatively affect growth performance and that feed costs could be reduced when using PF in all strains used in this study on a dollar/ kg of gain.
ACKNOWLEDGMENTS The authors are appreciative for the support of CobbVantress Inc. (Siloam Springs, AR) and the University of Arkansas Division of Agriculture (Fayetteville, AR) throughout this project.
REFERENCES Bilgili, S. F., M. A. Alley, J. B. Hess, and M. Nagara. 2006. Influence of age and sex on footpad quality and yield in broiler chickens reared on low and high density diets. J. Appl. Poult. Res. 15:433–441. Brewer, V., P. Pillai, A. Saha, C. Owens, J. Meullenet, and J. Emmert. 2006a. Phase-feeding in broilers: Impact on breast fillet dimension, cook loss and tenderness. Poult. Sci. 85(Suppl. 1):159. (Abstr.) Brewer, V. B., P. B. Pillai, T. O’Connor-Dennie, and J. L. Emmert. 2006b. Phase-feeding during the grower and finisher phases: Impact on growth, uniformity, and production cost. Poult. Sci. 85(Suppl. 1):205. (Abstr.) Emmert, J. L., and D. H. Baker. 1997. Use of the ideal protein concept for precision formulation of amino acid levels in broiler diets. J. Appl. Poult. Res. 6:462–470. Lubritz, D. L. 1997. A statistical model for white meat yield in broilers. J. Appl. Poult. Res. 6:253–259. Mehaffey, J. M., S. P. Pradhan, J. F. Meullenet, J. L. Emmert, S. R. McKee, and C. M. Owens. 2006. Meat quality evaluation of minimally aged broiler breast fillets from five commercial genetic strains. Poult. Sci. 85:902–908. NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. Peak, S. D., T. J. Walsh, C. E. Benton, J. Brake, and P. L. M. van Horne. 2000. Effects of two planes of nutrition on performance and uniformity of four strains of broiler chicks. J. Appl. Poult. Res. 9:185–194. Pope, T., and J. L. Emmert. 2001. Phase-feeding supports maximum growth performance of broiler chicks from forty-three to seventyone days of age. Poult. Sci. 80:345–352. Pope, T., L. N. Loupe, P. B. Pillai, and J. L. Emmert. 2004. Growth performance and nitrogen excretion of broilers using a phasefeeding approach from twenty-one to sixty-three days of age. Poult. Sci. 83:676–682. Pope, T., L. N. Loupe, J. A. Townsend, and J. L. Emmert. 2002. Growth performance of broilers using a phase-feeding approach with diets switched every other day from forty-two to sixty-three days of age. Poult. Sci. 81:466–471. Warren, W. A., and J. L. Emmert. 2000. Efficacy of phase-feeding in supporting growth performance of broiler chicks during the starter and finisher phases. Poult. Sci. 79:764–770. Young, L. L., J. K. Northcutt, R. J. Buhr, C. E. Lyon, and G. O. Ware. 2001. Effect of age, sex, and duration of postmortem aging on percentage yield of parts form broiler chicken carcasses. Poult. Sci. 80:376–379.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
Strain C
Strain D
Cost difference
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS
Key words: phase feeding, strain, broiler, yield 2012 Poultry Science 91:1256–1261 http://dx.doi.org/10.3382/ps.2011-01707
INTRODUCTION Commercial broiler production is a dynamic and ever-changing industry, and poultry nutritionists and researchers are not exempt from this change. Many recommendations have been made for the nutrient requirements of broilers at a wide variety of ages, as well a variety of feeding regimens to best meet these needs. The NRC (1994) has a single set of recommendations for both male and female broilers; however, these recommendations are rarely used in a commercial setting because these recommendations over-feed valuable nutrients throughout the life of the broiler. Less of the valuable nutrients in broiler diets are needed for the maintenance of muscle than for the accretion of muscle. Because of this, it is common practice in the poultry industry for commercial nutritionists to formulate as many as 6 diets for the growth of one flock to accurately meet nutritional needs. This may negatively affect ©2012 Poultry Science Association Inc. Received June 27, 2011. Accepted January 16, 2012. 1 Corresponding author: [email protected]
the meat quality of the modern high-yielding broiler, which accrue much of their muscle mass beyond 40 d of age and, therefore, actually need a more nutrient-dense diet in the later stages of grow out. However, it does reduce the cost of production by substantially reducing feed costs compared with the NRC recommendations. Phase feeding (PF) describes the philosophy of feeding broilers over shorter periods of time with the goal of precisely feeding broilers to meet, but not exceed, their amino acid requirements. Emmert and Baker (1997) developed a series of regression equations that are the basis of PF. Using these equations, digestible amino acid content of a diet is expressed as a function of age. Therefore, amino acid requirements for broilers can be predicted at a wide variety of ages, and excess dietary amino acids and CP can be eliminated. Phase feeding has been used switching diets weekly (Pope and Emmert, 2001) and every other day (Pope et al., 2002; Brewer et al., 2006b). The nature of the PF regimen and the regression equations used to formulate the diets allow for a variety of feeding intervals to be used. In previous research, PF has maintained growth and parts yields while improving feed efficiency and uni-
1256
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
ABSTRACT Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains and sex has not been assessed. An experiment was conducted using 4 commercial broiler strains grown up to 63 d of age (n = 1,440), comparing a PF approach to an industry-type diet. At d 17, birds began either the industry or PF regimen. The industry regimen consisted of average industry nutrient levels with periods from 17 to 32 d, 32 to 40 d, 40 to 49 d, and 49 d to the end of trial. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient density diets were blended to produce rations containing amino acid levels
1257
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS Table 1. Percentage of composition of basal diets, as-fed basis Industry Item Ingredient Corn Soybean meal Poultry fat Vitamin mineral mix Dicalcium PO4 Limestone NaCl dl-Methionine l-Threonine Composition ME,2 kcal/kg CP, % Total Lys, % Total Met, % Total Cys, % Total Thr, %
17–32 d
32–40 d
40–49 d
49–59 d
65.6 28.0 2.50 0.30 1.55 1.25 0.40 0.246 0.070 3,100 19.3 1.10 0.52 0.31 0.78
69.1 24.5 2.66 0.30 1.32 1.25 0.35 0.264 0.043 3,150 17.9 1.00 0.39 0.43 0.70
69.8 23.5 3.25 0.30 1.25 1.10 0.35 0.222 0.040 3,200 17.5 0.97 0.36 0.41 0.68
71.2 22.4 3.00 0.30 1.25 1.10 0.35 0.222 0.040 3,200 17.1 0.94 0.47 0.29 0.65
PF HN1
PF LN1
17–19 d
57–59 d
62.0 31.2 2.96 0.30 1.50 1.25 0.40 0.216 0.039 3,100 20.5 1.19 0.41 0.44 0.80
79.2 16.6 1.03 0.30 1.20 1.10 0.35 0.072 0.024 3,150 14.9 0.76 0.28 0.30 0.56
formity, when compared with both NRC and a typical industry-type feeding regimen (Warren and Emmert, 2000; Pope and Emmert, 2001; Pope et al., 2002; Brewer et al., 2006b). Phase feeding has also been shown to reduce nitrogen excretion and improve broiler performance during periods of heat stress (Pope and Emmert, 2001). However, previous research with PF has always been conducted with a male breeder by-product of one commercial strain. There are many strains available for broiler production, and much research has been conducted on the performance of various broiler strains. Some strains have improved growth and parts yield, especially breast yield, compared with others (Peak et al., 2000; Bilgili et al., 2006; Mehaffey et al., 2006). Also, typically male and female broilers are reared together. Research conducted where both genders were evaluated has indicated differences in the growth and in the yield of male and female broilers (Young et al., 2001). Therefore, the objective of this study was to evaluate the effect of PF, strain, and sex on growth performance, feed efficiency, parts yield, fillet dimension, and uniformity.
MATERIALS AND METHODS All procedures were approved by the University of Arkansas Institutional Animal Care and Use Committee. For this experiment, 4 commercial strains commonly used in industry were reared up to 63 d to simulate a big-bird production scenario. The strains were bred to be high or moderate breast-yielding broilers, and all strains are used in typical industry big-bird programs. A factorial arrangement of treatments was used with 4 strains and 2 diets, resulting in 8 experimental treatments; treatments were replicated 6 times (n = 1,440 total). Birds, 15 male and 15 female chicks per pen, were reared in floor pens. On d 3, all chicks were
weighed and allotted to pens so that initial pen weight was uniform; wing bands were used for individual identification throughout the trial period. Prior to d 3, birds were held in groups according to strain and sex. From 0 to 17 d, all treatments were fed a common starter diet. At d 17, the trial period began and birds were fed either an industry-type diet or a PF regimen (Table 1). Treatments were held on a 23L:1D photoperiod and both water and experimental diets were provided ad libitum.
Phase-Feeding Regimen Phase-feeding regimens were based on regression equations from Emmert and Baker (1997) and were used to predict every-other-day amino acid requirements as follows: digestible Lys, y = 1.22 – 0.0095x; digestible Met and Cys, y = (0.88 – 0.0063x)/2; and digestible Thr, y = 0.8 – 0.0053x, where y = digestible amino acid level, and x = midpoint (day) of the desired age range. For this regimen, a high-nutrient (HN) diet was formulated for predicted amino acid requirements for 17 to 19 d, and the low-nutrient (LN) diet was formulated for predicted amino acid requirements for 58 to 60 d (Table 1). The HN and LN diets were blended to produce the PF diets throughout the trial period; there were 22 intermittent blends of the formulated HN and LN diets. The industry regimen was based on averaged industry nutrient levels, and periods were as follows: grower (17–32 d), finisher 1 (32–40 d), finisher 2 (40–49 d), and withdrawal (49 to end of trial). To assess growth performance, birds were individually weighed, and feed was weighed at d 3, 17, 32, 40, and 49. On d 58, one day before processing, group weights were measured for feed intake and feed efficiency (FE; gain:feed) data, and individual live weights were measured at the dock before processing. Weight gain, feed intake, and FE were determined through d 58. Mortal-
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
1Phase feeding (PF) diets were formulated to contain Lys, sulfur amino acid, and Thr levels predicted by linear regression equations for 17- to 19-dold [PF high nutrient (HN)] or 57- to 59-d-old [PF low nutrient (LN)] broilers. Experimental diets were produced by blending PF HN and PF LN diets invariable quantities (see Materials and Methods). 2ME data represent calculated values; all other data represent analyzed values.
1258
1,031b 534ab 575b 588ab 2,728ab 1,659b 998a 1,389bc 1,551abc 5,593ab 622ab 536ab 411ab 382ab 488ab 3,170bc 1,031b 516bc 563b 529abc 2,641ab 1,663b 969a 1,390bc 1,306cd 5,325b 621ab 534abc 405ab 402a 495a 3,096cd 1,105a 524bc 489d 535abc 2,657ab 1,757a 1,021a 1,310c 1,391bcd 5,475b 630a 513bc 372c 390ab 484ab 3,138bcd within a row lacking a common superscript differ (P < 0.05). = phase feeding. 2Data combined across sex for strain and feeding regimen comparison. 3Data combined across 3 processing days: d 59, 61, and 63. 1PF
a–eValues
Final BW2,3 (g)
Feed efficiency2 (G:F, g:kg)
Feed intake2 (g/chick)
17–32 32–40 40–49 49–58 17–58 17–32 32–40 40–49 49–58 17–58 17–32 32–40 40–49 49–58 17–58 Weight gain2 (g/chick)
d d d d d d d d d d d d d d d
1,006bc 509c 543bc 561abc 2,619ab 1,652b 986a 1,413abc 1,583bc 5,629ab 609bc 515bc 385bcd 360ab 466c 3,119cd
996c 516bc 498d 478bc 2,488b 1,608b 994a 1,316c 1,461bcd 5,376b 619ab 519bc 379cd 329b 463c 2,997e
992c 557a 623a 641a 2,811a 1,611b 1,005a 1,520a 1,802a 5,933a 613ab 554a 411ab 357ab 475bc 3,320a
991c 550a 618a 614ab 2,775a 1,587b 1,030a 1,468ab 1,625ab 5,706ab 625ab 534abc 422a 382ab 485ab 3,231ab
1,078a 457d 516cd 456c 2,508b 1,821a 921a 1,294c 1,197d 5,229b 593c 496c 398abc 379ab 479abc 3,035de
Industry PF Industry
PF
Strain C Strain B
PF1 Industry Period Item
Phase feeding as a main effect significantly affected weight gain during the 32 to 40 d and 40 to 49 d growth periods (P = 0.0003 and P = 0.0333, respectively); however, there was a significant interaction between strain and feeding regimen for those periods. Therefore, the interactions for growth parameters are presented in Table 2. Phase feeding did not affect weight gain of broilers, with the exception of strain A from 40 to 49 d and strain C from 32 to 40 d. However, the effect of PF in these 2 instances was different. Weight gain was increased with strain C due to PF and was decreased with strain A due to PF in the before-mentioned periods. For the overall growth period (17–58 d), there was no significant effect of PF on weight gain for any strain (P = 0.7716). Furthermore, there was no effect of PF on feed intake over any growth period, including the overall growth period (P = 0.9510). Strain had a greater effect on feed intake; however, it varied depending on feeding regimen and growth period. Also, there was no difference in FE between industry and PF
Strain A
RESULTS AND DISCUSSION
Table 2. Effect of strain and feeding regimen on weight gain, feed intake, feed efficiency, and BW
The experiment was analyzed as a randomized complete block design with a factorial arrangement of treatments (strain, diet, sex). For weight gain, BW, and yields, and individual bird was the experimental unit; for feed intake and FE, pen was the experimental unit. The GLM procedure of SAS was used to conduct ANOVA on all data. For feed data differences among treatments, means were established using the least significant difference multiple comparison procedure. For growth, yield and fillet dimension data differences were established using Duncan’s multiple-range test. Differences were considered significant at P < 0.05. In this study, deboning hour did not significantly affect yield; therefore, yield data was pooled across all deboning hours. Debone hour did significantly affect fillet dimension; therefore, only the data of fillets deboned at 6 h PM is presented.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
Statistical Analysis
Industry
Strain D
PF
Pooled SEM
ity and culls were accounted for daily and all calculations were adjusted accordingly. Mortality was approximately 6% for the overall grow-out period (through 58 d). Following a 10-h feed-withdrawal period, birds were processed at the university pilot poultry processing plant using commercial methods (Mehaffey et al., 2006). Briefly, birds were stunned, exsanguinated, scalded, picked, and eviscerated on an in-line commercial-type system, followed by chilling to 4°C internal temperature. Processing took place over 3 d (d 59, 61, 63), 2 replicates per day, and carcasses were deboned at 2, 4, and 6 h postmortem (PM) and parts weighed to determine yields. Fillet dimensions were measured at 24 h PM on fillets deboned at 6 h PM, according to procedures described by Mehaffey et al. (2006) for an additional assessment of growth performance.
4.0 3.1 4.5 15.5 32.2 14.3 12.0 17.7 42.4 67.6 2.6 4.6 4.1 7.6 2.7 13.2
Brewer et al.
1259
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS Table 3. Body weights of males and females from 4 high-yielding broiler strains Strain A BW1 (g)
Female
Day 3 Day 17 Day 32 Day 40 Day 49 Final BW2
77d 472d 1,411d 1,883e 2,355e 2,870e
Strain B
Male 78d 503c 1,565c 2,116c 2,678c 3,263c
Female
Male
74e 447e 1,385d 1,887e 2,459d 3,031d
Strain C Female
79d 492c 1,542c 2,145bc 2,837a 3,561a
Male
87b 522b 1,537c 2,005d 2,485d 2,947de
Strain D Female
93a 572a 1,733a 2,245a 2,761b 3,247c
83c 466d 1,411d 1,875e 2,394e 2,879e
Pooled SEM
Male 77d 490c 1,608b 2,185b 2,809ab 3,411b
0.3 2.0 5.4 7.1 9.1 13.2
a–eValues
within a row lacking a common superscript differ (P < 0.05). combined across feeding regimen for strain and sex comparison. 2Data combined across 3 processing days: d 59, 61, and 63. 1Data
accelerated growth during the later periods, after 40 d, weighing more at the time of processing than strain C. By d 49, strain B males were significantly heavier than strains A and C, with no difference between strain B and D males. For the females, strain C also had accelerated growth early, by d 17 through d 40, compared with other strains. However, although strain C was larger than strain A at d 17, 32, 40, and 49, there was no difference in BW at processing for these 2 strains, suggesting strain C had a slower growth rate toward the end of grow out. Similar to the males, females of strain B had accelerated growth beyond d 40 and were similar in BW to females of strain C but significantly heavier than females of strains A and D at d 49 and at processing. Differences in growth patterns among the strains can be expected because they have varying selection parameters in the breeding programs. Males weighed significantly more than females at all days measured during grow out. As expected, especially with the overall length of grow out, these differences between sexes became larger as the grow-out period increased. Overall, these growth data for strain indicate that strains B and D are more suited to longer grow outs because they had significantly greater live weights at processing (i.e., 60 d). Carcass and breast yield were assessed to determine processing performance as a result of dietary regimen changes. Phase feeding did not affect carcass yield in any strain, as indicated by no significant differences in ready-to-cook yield between industry and PF dietary treatments (Table 4). Generally, PF did not affect breast yield in strains B, C, and D, as indicated by no
Table 4. Yields of broilers from 4 high-yielding strains fed industry or phase-feeding (PF) diets Strain A Item RTC yield1,2,3 (%) Fillet yield1,2,4 (%) Tender yield1,2,4 (%) Total breast1,2,4 (%) a–cValues
Strain B
Industry
PF
78.4 22.5b 5.65a 28.1b
78.1 21.8c 5.48b 27.4c
Strain C
Industry
PF
78.6 23.5a 5.66a 29.1a
78.7 23.4a 5.58ab 29.0a
within a row lacking a common superscript differ (P < 0.05). averaged over 3 processing days: d 59, 61, and 63. 2Data averaged over 3 debone times: 2, 4, and 6 h postmortem. 3Ready-to-cook (RTC) yield expressed as percentage of live weight. 4Parts yield expressed as a percent of RTC weight. 1Data
Strain D
Industry
PF
78.7 22.2bc 5.57ab 27.8b
79.1 22.1bc 5.49b 27.6bc
Industry
PF
78.9 23.6a 5.68a 29.3a
78.6 23.5a 5.68a 29.2a
Pooled SEM
0.09 0.07 0.03 0.07
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
regimens for the overall period (P = 0.6522) or other periods, with the exception of one instance where strain C had improved FE with the PF regimen during the 17 to 32 d period. As a main effect, feeding regimen did not significantly affect BW at processing (P = 0.5660); however, there was a significant strain by feeding regimen interaction (P = 0.0021). Strain A had decreased BW at processing with PF, whereas strain C had slightly increased BW with the PF regimen at the time of processing (Table 2). The lower gains for strain A over growth periods beyond 40 d, taken cumulatively, likely resulted in the decreased final BW for this strain. These data could indicate that strain A requires a higher level of amino acid density in the diet. Body weights of the strains over the grow-out period are presented in Table 3. Significant differences in BW among strains were observed as early as 3 d. Strain C had the heaviest chicks at 3 d, followed by chicks from the other strains. For males, chicks did not differ in weight between strains A, B, and D. However, for females, 3-d-old chicks from strain C chicks were the heaviest, followed by chicks from strains D, A, and B, which all differed (P < 0.05) from each other. Broilers from strain C had consistently heavier BW at all days measured from 17 to 40 d, compared with other strains for both males and females. All strains varied in growth pattern form 17 to 58 d. For example, strain C males gained significantly more during the early growth periods and then decreased compared with other strains after 40 d. Strains B and D males gained slower during the beginning growth periods, up to 32 d, and then had
1260
Brewer et al.
Table 5. Fillet dimensions of broiler breast fillets from 4 high-yielding strains fed industry or phase-feeding (PF) diets Strain A
Strain B
Item
Industry
PF
Fillet weight1 (g) Length1 (cm) Width1 (cm) Cranial thickness1 (cm) Caudal thickness1 (cm)
546c 19.2b 9.79ab 2.75cde 0.92bcd
504d 18.7c 9.59b 2.62e 0.85d
a–eValues
Strain C
Industry
PF
612a 19.0bc 10.0a 3.01ab 1.04ab
594a 19.0bc 9.81ab 3.15a 1.08a
Strain D
Industry
PF
522d 19.5ab 9.72b 2.69cde 1.02abc
507d 19.4ab 9.88ab 2.66de 0.89cd
Industry
PF
574b 19.4ab 9.79ab 2.88bc 1.09a
582b 19.6a 9.76ab 2.85bcd 0.98abcd
Pooled SEM
3.25 0.20 0.14 0.06 0.03
within a row lacking a common superscript differ (P < 0.05). over 3 processing days: d 59, 61, and 63; data of fillets deboned at 6 h only.
1Averaged
in dollars per kilogram of breast meat, as previously reported (Pope et al., 2002; Brewer et al., 2006a,b). Feed savings with PF result from more accurately targeting amino acid requirements of broilers and not overfeeding expensive nutrients. As described by Pope et al. (2002), formulation of PF diets over 2-d intervals is simply not feasible, especially when considering a commercial industry spectrum and addition of cost of feed delivery. However, the PF regimen used in this study and also by Pope et al. (2002) had only 2 diets formulated, and these 2 diets were blended to produce the PF rations. For this to work on a commercial level the HN and LN diets would be delivered to the farm and the diets would be blended using feed equipment on the farm (Warren and Emmert, 2000). In this study, PF feed costs were significantly lower for strain C compared with industry during the grower (17–32 d) period; there were no significant differences due to feeding regimen for strains A, B, and D during that period (Table 6). There were no significant differences in feed cost due to feeding regimen during finisher 1 (32–40 d), finisher 2 (40–49 d), or withdrawal (49–58 d) for any strain. When evaluating costs for the overall period, PF cost significantly less in dollars per kilogram of gain ($0.04 difference) in strain B but not in other strains. However, for all the strains used in this study, the cost difference on a per kilogram of gain basis ranged from $0.01 to $0.04 in all strains, and though not statistically significant, these results are similar to previous research where PF has resulted in a reduction in feed cost between PF and NRC regimen of $0.01/kg of gain and $0.06/kg of breast meat (Pope et al., 2002, 2004). There was some variation among strains in feed cost for birds on the industry diet. Strain D had a significantly lower overall (17–58 d) cost (dollars/kg of gain) compared with strain A, whereas strains B and C were intermediate. When considering feed costs for dollars per kilogram of breast meat, strain D was significantly less expensive to produce compared with strains A and C, but similar to strain B. These differences in costs associated with growth could be attributed to the selection characteristics used in their breeding programs. These decreases in production cost related to feed, not significant in all cases, could seem trivial on a per kilogram basis. However, the large production volume of the poultry industry converts these seemingly small reductions in production costs into substantial savings. Though savings are variable among the strains, PF
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
significant difference in fillet, tender, or total breast yield between industry and PF. With strain A, PF resulted in significantly lower fillet, tender, and total breast yield. This could be attributed to an increased nutritional need for strain A compared with the other strains evaluated. In previous research, a decrease in breast yield was observed when PF amino acid levels were decreased by 10% (PF 10) though normal PF diets had no negative effect on yield (Pope et al., 2002; Brewer et al., 2006b). Therefore, if a broiler had increased nutritional needs in this study, it is possible that breast yield would be reduced. Strain affected breast yields also (Table 4). Strains that showed accelerated growth through the final periods (e.g., strains B and D) are also the strains that had significantly greater breast yield (fillet and total breast). There was no significant difference in breast yield (fillet and total breast) for strains A and C, and they both yielded significantly less than strains B and D, which were similar. These results could be attributed to the possible differences in breeding selection programs for the various strains. Fillet dimensions were also measured and are presented in Table 5. With the exception of strain A, fillet dimensions were not affected by PF, as indicated by no significant difference in the length, width, and height of fillets between industry and PF treatments. In strain A, PF treatments had significantly lower fillet weight and length compared with industry feeding treatments, while no other dimensions were affected. Therefore, it appears that the decrease in yield observed for strain A can be attributed to the decrease in fillet length with the PF treatments. However, Lubritz (1997) suggested that fillet thickness has 7 times more impact on fillet weight than length or width. So, perhaps it was a combination of decreased fillet length and thickness (0.13 cm numerical difference in cranial thickness, though not significant) that were associated with a decrease in fillet weight for the PF regimen with strain A. Strain also affected fillet dimension (Table 5). Strains C and D had significantly longer fillets than strains A and B, with no difference in width for any strains. Increased fillet yield that was reported with strains B and D can be attributed to the thickness of the fillet. At both the cranial and caudal region, the fillets for these strains were significantly thicker than strains A and C. The main advantage of the PF regimen compared with a typical industry regimen is the decrease in cost of feed not only in dollars per kilogram of gain but also
within a row lacking a common superscript differ (P < 0.05). difference = industry feed costs – PF feed costs in dollars/kg. Values in parentheses denote that PF costs more than industry. 2Feed cost per bird was first determined by multiplying the amount of feed consumed by the dietary cost, which was calculated based on values of $0.2425/kg for corn, $0.3968/kg for soybean meal, $1.1908/kg for l-lysine HCl, $3.3069/kg for dl-methionine, and $4.1887/kg for l-threonine. Feed cost per bird was then divided by the weight gain per bird. 3Calculated by dividing the feed cost per bird by the amount of breast meat (fillet and tenders) per carcass. 1Cost
$/kg of breast3
a–dValues
0.00 0.02 0.04 (0.01) 0.01 (0.01) 0.49bc 0.55b 0.70bc 0.75 0.60d 2.27b 0.49bc 0.57ab 0.74abc 0.74 0.61bcd 2.26b 0.03 0.03 (0.03) 0.05 0.02 0.01 0.49c 0.58ab 0.78a 0.75 0.61cd 2.40a 17–32 32–40 40–49 49–58 17–58 $/kg of gain2
Cost
Age
d d d d d
0.51ab 0.59ab 0.78a 0.83 0.65a 2.48a
0.49bc 0.57ab 0.76ab 0.85 0.63abc 2.48a
0.02 0.02 0.02 (0.02) 0.02 0.00
0.50bc 0.54b 0.73abc 0.83 0.64ab 2.37ab
0.49bc 0.56b 0.68bc 0.74 0.60d 2.27b
0.01 (0.02) 0.05 0.08 0.04 0.10
0.52a 0.61a 0.75abc 0.80 0.63abc 2.41a
PF Ind. Cost difference PF Ind. Cost difference PF Ind.
PF
Cost difference1
Ind.
Strain B Strain A
Table 6. Feed costs associated with industry (Ind.) and phase-feeding (PF) diets for 4 high-yielding broiler strains
1261
could still potentially save companies billions of dollars in feed costs.
Conclusion In conclusion, PF did not negatively affect weight gain or feed efficiency over the overall grow-out period (17–58 d). Furthermore, yields (ready to cook, fillet, and total breast) were not negatively affected by PF in most strains. Strain and sex had significant effects on growth performance, yield, and fillet dimensions. Results suggest that PF does not negatively affect growth performance and that feed costs could be reduced when using PF in all strains used in this study on a dollar/ kg of gain.
ACKNOWLEDGMENTS The authors are appreciative for the support of CobbVantress Inc. (Siloam Springs, AR) and the University of Arkansas Division of Agriculture (Fayetteville, AR) throughout this project.
REFERENCES Bilgili, S. F., M. A. Alley, J. B. Hess, and M. Nagara. 2006. Influence of age and sex on footpad quality and yield in broiler chickens reared on low and high density diets. J. Appl. Poult. Res. 15:433–441. Brewer, V., P. Pillai, A. Saha, C. Owens, J. Meullenet, and J. Emmert. 2006a. Phase-feeding in broilers: Impact on breast fillet dimension, cook loss and tenderness. Poult. Sci. 85(Suppl. 1):159. (Abstr.) Brewer, V. B., P. B. Pillai, T. O’Connor-Dennie, and J. L. Emmert. 2006b. Phase-feeding during the grower and finisher phases: Impact on growth, uniformity, and production cost. Poult. Sci. 85(Suppl. 1):205. (Abstr.) Emmert, J. L., and D. H. Baker. 1997. Use of the ideal protein concept for precision formulation of amino acid levels in broiler diets. J. Appl. Poult. Res. 6:462–470. Lubritz, D. L. 1997. A statistical model for white meat yield in broilers. J. Appl. Poult. Res. 6:253–259. Mehaffey, J. M., S. P. Pradhan, J. F. Meullenet, J. L. Emmert, S. R. McKee, and C. M. Owens. 2006. Meat quality evaluation of minimally aged broiler breast fillets from five commercial genetic strains. Poult. Sci. 85:902–908. NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. Peak, S. D., T. J. Walsh, C. E. Benton, J. Brake, and P. L. M. van Horne. 2000. Effects of two planes of nutrition on performance and uniformity of four strains of broiler chicks. J. Appl. Poult. Res. 9:185–194. Pope, T., and J. L. Emmert. 2001. Phase-feeding supports maximum growth performance of broiler chicks from forty-three to seventyone days of age. Poult. Sci. 80:345–352. Pope, T., L. N. Loupe, P. B. Pillai, and J. L. Emmert. 2004. Growth performance and nitrogen excretion of broilers using a phasefeeding approach from twenty-one to sixty-three days of age. Poult. Sci. 83:676–682. Pope, T., L. N. Loupe, J. A. Townsend, and J. L. Emmert. 2002. Growth performance of broilers using a phase-feeding approach with diets switched every other day from forty-two to sixty-three days of age. Poult. Sci. 81:466–471. Warren, W. A., and J. L. Emmert. 2000. Efficacy of phase-feeding in supporting growth performance of broiler chicks during the starter and finisher phases. Poult. Sci. 79:764–770. Young, L. L., J. K. Northcutt, R. J. Buhr, C. E. Lyon, and G. O. Ware. 2001. Effect of age, sex, and duration of postmortem aging on percentage yield of parts form broiler chicken carcasses. Poult. Sci. 80:376–379.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on May 11, 2015
Strain C
Strain D
Cost difference
PHASE FEEDING IN BIG-BIRD PRODUCTION SYSTEMS