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Effect of Dietary Lysine on Yield Losses Occurring During Early Feed Restriction to Reduce Ascites
2001 Poultry Science Association, Inc.
EFFECT OF DIETARY LYSINE ON YIELD LOSSES OCCURRING DURING EARLY FEED RESTRICTION TO REDUCE ASCITES N. ACAR1, R. M. HULET, and G. F. BARBATO Department of Poultry Science, The Pennsylvania State University, University Park, Pennsylvania 16802 Phone: (814) 863-8960 FAX: (814) 865-5691 e-mail: [email protected]
SUMMARY This study evaluated additions of dietary lysine to restore yield losses from feed restriction to reduce ascites. Feed restriction was used to limit daily feed intake of the birds to 75% of the metabolizable energy required for normal growth, based on the ad libitum intake of the birds. Grower and finisher diets contained normal lysine (NL) or high lysine (HL). Final body weight of feed-restricted birds was 96% of birds fed ad libitum, indicating that “catch-up” growth was not sufficient to equalize the body weights by 56 d of age between birds on feed restriction and those fed ad libitum. Feed-restricted birds were fatter than those birds fed ad libitum. HL reduced the deficit in the percentage pectoralis minor muscle yield compared with birds fed NL diets, whereas the percentage yield of pectoralis major muscle remained unaffected by dietary lysine. Feed restriction reduced the total ascitic mortality in the cool and control environments. It was concluded that increased lysine did not have any beneficial effect on the final body weight, percentage carcass yield, or any of the carcass characteristics, with the exception of pectoralis minor muscle yield, which was increased when birds were fed HL. Key words: Ascites, broilers, carcass yield, feed restriction, live performance, lysine 2001 J. Appl. Poult. Res. 10:211–220
DESCRIPTION OF PROBLEM Ascites is characterized by an accumulation of fluid in the abdominal cavity of affected birds followed by death [1]. When broiler chickens are selected for increased growth rate and meat yield, metabolic disorders, such as ascites, often accompany the rapid growth. Olkowski et al. [2] have indicated that ascites has become a major economic concern in the broiler industry worldwide. Odom [3] reported that economic losses due to ascites in the United 1
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States have been estimated to exceed $100 million dollars annually. Feed restriction regimens at early ages reduce ascites mortality [4, 5, 6] by slowing the early growth of lean muscle [7]. In our laboratory, ascites has been successfully induced with a “cool model” [4], and the incidence of ascites has been reduced by restricting the feed (growth) to 75% of that ad libitum between 4 and 11 d posthatching [6]. However, early feed restriction results in birds having significantly smaller body weights at a given age than birds
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Primary Audience: Nutritionists, Poultry Producers
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212 fed ad libitum. Further, some early feed-restricted birds tend to have larger abdominal fat pads [8, 9, 10]. Acar et al. [6] also found a breast yield loss due to feed restriction, agreeing with reports by van Harn and Fabri [7]. Our objective in the present study was to determine if muscle-augmenting nutritional strategies of increased dietary lysine would impact breast yield or influence ascites susceptibility.
“COOL MODEL” TO INDUCE ASCITES
MATERIALS AND METHODS
CARCASS YIELD
From Days 14 through 56, birds were exposed to cool temperatures in one room to induce ascites. To obtain this temperature, the thermostat was set for 13°C, and the ventilation controller opened inlets for cool winter air or called for supplemental heat. The experiment was conducted between October and December.
FEED RESTRICTION PROGRAM
MORTALITY
All birds were provided a common starter diet (3,200 kcal/kg metabolizable energy, 23.0% CP, and 1.2% lysine) from 1 to 4 d of age. The feed restriction protocol was used to limit daily feed intake of the birds to 75% of the metabolizable energy required for normal growth of birds fed ad libitum from 4 to 11 d of age. Thereafter, the diet was provided for consumption ad libitum. Restricted-fed birds and birds fed ad libitum were weighed, and feed consumption of birds fed ad libitum was measured daily to calculate the daily allowance of the feed-restricted birds [6]. After feed restriction, the body weights of chicks and feed consumption were recorded weekly for each pen. Commercially mixed grower (3,195 kcal/ kg metabolizable energy and 20% CP from 22 to 42 d of age) and finisher (3,190 kcal/kg metabolizable energy and 18% CP from 43 to 56 d of age) diets contained normal lysine (NL; 1.00 and 0.85%) [NRC, 11] or high lysine (HL; 1.15 and 1.00%), respectively.
Dead birds were recorded and examined for gross lesions of ascites, such as amber-colored fluid in the abdominal cavity and in pericardium and enlarged heart and right ventricle. All data were subjected to statistical analysis [12, 13, 14, 15]. STATISTICAL ANALYSIS The data were analyzed by analysis of variance by using the general linear models procedure of SAS software [12]. From 1 to 21 d of age, feed restriction vs. ad libitum feed treatments (feeding regimen effect) and cool vs. control treatments (temperature effect) were compared (two-way ANOVA). From 22 to 56 d of age, dietary lysine effect was added into the model (three-way ANOVA). Tukey’s multiple comparison was performed when F test was significant [13]. Mortality data were analyzed by weighted ANOVA after arc sine square root percentage transformations [14].
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A total of 1,776 1-d-old male broilers of a commercial strain cross were wing-banded and placed in two identical rooms in an environmentally controlled house. Treatments within each room were feeding regimen (ad libitum vs. feed restriction) and dietary lysine (NRC [11] normal lysine levels vs. high lysine). Within each room, feeding regimen and lysine treatments were replicated six times for a total of 48 floor pens. Lighting was continuous. Birds were vaccinated for Marek’s disease at hatch.
Five birds from each pen were randomly selected and processed according to commercial practices at 56 d of the experiment. Fat pads were removed from the abdominal cavity and weighed. Carcasses were chilled in the slush ice overnight. The next day, chilled carcasses were hung on the lines to let the water drip for approximately 5 min. Carcasses were cut into the following pieces and then weighed: wings, drumsticks, breast fillet (pectoralis major muscle), tenders (pectoralis minor muscle), thigh meat, and “cage” (remaining ribcage, skin and fat).
BIRDS AND HOUSING
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TABLE 1. Composition of experimental diets (% of diet) GROWER INGREDIENT
Calculated composition Metabolizable energy, kcal/kg Crude protein, % Lysine, % Methionine, % Cystine, % Analyzed compositionF Crude protein, % Lysine, % Methionine, % Cystine, %
Normal lysine 68.22 20.30 5.00 ... 2.50 2.00 0.259 1.102 0.30 0.024 0.033 0.13 0.25 100.001
A
High lysine 68.15 19.85 5.00 ... 2.50 2.35 0.261 1.105 0.30 0.021 0.196 0.13 0.25 99.996
FINISHER
FINISHER A
Normal lysine 71.47 14.95 4.50 5.00 2.205 0.35 ... 0.972 0.30 0.002 ... ... 0.25 99.999
High lysineA 70.63 15.30 4.45 5.45 2.50 ... ... 0.975 0.30 0.004 0.141 ... 0.25 100.000
3,195 20.00 1.00 0.38 0.35
3,195 20.00 1.15 0.38 0.35
3,190 18.00 0.85 0.32 0.33
3,190 18.00 1.00 0.32 0.33
19.98 0.96 0.35 0.34
19.96 1.11 0.35 0.35
18.01 0.82 0.29 0.33
17.99 0.93 0.32 0.34
Grower diet formulated to contain normal levels of lysine (NL) = (1.0%) or high lysine (HL) = (1.15%); finisher diet contained normal lysine levels (NL), 0.85% or high lysine (HL), 1.00%. Contained 16% Ca and 21% available P. C Contained 38% Ca. D Amprolium (Amprol 25%), Merck & Co., Inc., Rahway, NJ 07065-0912. E Supplied the following per kilogram of vitamin and mineral premix: Vitamin A, 2,640,000 IU (retinyl acetate); cholecalciferol, 880,000 ICU; vitamin E, 6,600 IU (dl-α-tocopherol acetate); menadione, 660 mg; thiamine, 440 mg; riboflavine, 1,760 mg; niacin, 13,200 mg; pantothenic acid, 3,080 mg; pyridoxine, 660 mg; folic acid, 220 mg; biotin, 22 mg; vitamin B12, 3,520 µg; manganese, 26,400 mg; zinc, 22,000 mg; iron, 11,000 mg; copper, 1,760 mg; iodine, 220 mg. F Amino acid analysis of the diets was done by Degussa Corp., Allendale, NJ 07401. A B
RESULTS AND DISCUSSION LIVE PERFORMANCE Analyzed crude protein and calculated energy levels of the diets met the NRC [11] requirements for broilers. Actual lysine levels for the experimental diets (both grower and finisher diets) were from 0.03 to 0.07% lower than the initial formulation (Table 1). Broilers had equal body weights at hatch (49 g) and at 4 d of age (P > 0.05). Feed restriction significantly reduced the body weight and feed intake and increased the feed conversion of the birds from 4 to 11 d of age (Table 2).
At 11 d, body weight of feed-restricted birds was 66% of that of the birds fed ad libitum. Upon realimentation, weight gain was significantly higher (119 vs. 113 g) and feed conversion was better for the feed-restricted birds at 11 to 14 d of age than for the birds fed ad libitum, whereas at 14 d, body weights of feedrestricted birds were 78% of those of the birds fed ad libitum. At 14 d of age, half of the birds were exposed to the cool temperatures to induce ascites. Body weights were reduced by the cool temperatures for both groups of birds; feed-restricted birds weighed up to 85% of the 21-d body weights of birds fed ad libitum (Table 3). Feed
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Ground corn Soybean meal (48% CP) Animal by-product (65% CP) Canola meal Blended fat (8,140 kcal/kg, ME) Corn gluten meal (60% CP) Mono/dicalcium phosphateB LimestoneC Salt DL-Methionine L-LysineⴢHCl CoccidiostatD Vitamin-trace mineralsE Total
GROWER A
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TABLE 2. Live performance of broilers subjected to early feed restrictionA FEED CONVERSION (g feed intake/g weight gain)
BODY WEIGHT (g) TREATMENT Ad libitum Restricted SEMB Significance
4d
11 d
94 94
263 173
0.36 NS
0.86 ***
14 d 376 292 1.20 ***
4–11 d
11–14 d
1.47 1.76
1.48 1.29
0.007 ***
0.011 ***
conversion was better for the restricted birds than the birds fed ad libitum; cool temperatures increased feed conversion significantly (P < 0.01). At 42 d, body weights of feed-restricted birds were 96% of those of the birds fed ad libitum (2,043 vs. 2,128 g). A significant lysine effect indicated that feed conversion was improved for the HL birds when compared to the NL fed birds (2.00 vs. 2.06). Feed conversion was poorer for the birds in the cool environment (2.08 vs. 1.98) than in the control environment, whereas feed-restricted birds had lower feed conversions than the birds fed ad libitum. At 56 d of age, feed-restricted birds did not attain the same body weights as the control birds (3,172 vs. 3,061 g), whereas there were no treatment differences in feed conversions (Table 4).
Early feed-restriction regimens can be used as a management tool to reduce ascitic mortality in rapidly growing broiler chickens [4, 5, 6]. Upon realimentation, birds presumably recover from the growth deficit resulting from limited nutrient intake during feed restriction. This recovery is based on severity and length of feed restriction. According to Plavnik and Hurwitz [15] birds fully compensated for the weight loss when grown to 8 wk after early feed restriction and had improved feed conversion. However, studies using faster-growing or high-yielding contemporary commercial strains of broilers [6, 10] did not achieve complete “catch-up” growth by 7 or 8 wk of age, respectively. It is possible that this finding was attributable to genetic differences [16] and severity of the feed restriction relative to the growth. Jones and Farrell [17]
TABLE 3. Live performance of broilers subjected to early feed restriction and cool temperaturesA (21 d of age) TREATMENT
TEMPERATURE EFFECT
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
Ad libitum
Control Cool
723a 676b
1.47b 1.53c
Restricted
Control Cool
606c 582d
1.40a 1.44b
SEMB Significance Feeding regimen (F) Temperature (T) F×T A
6.2 *** *** *
All values represent the average of 12 pens each having 36 birds. Standard error of the mean. *P < 0.05; **P < 0.01; ***P < 0.001; NS, P > 0.05. a–c Means within a column having different superscripts are significantly different (P < 0.05). B
0.014 *** ** NS
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A All values represent the average of 24 pens, each having 36 birds. Average chick weight at 1 d of age was 49 g for all treatments. B Standard error of the mean. ***P < 0.001; NS, P > 0.05.
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
42 d
21–42 d
56 d
42–56 d
TEMPERATURE EFFECT
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Ad libitum
Control Cool
2,164a 2,071bc
2,178a 2,098b
2.06cd 2.17e
2.00b 2.09d
3,158ab 3,181ab
3,167ab 3,182
2.57 2.47
2.56 2.40
Restricted
Control Cool
2,033cd 2,023d
2,107b 2,008d
1.97b 2.03bc
1.88a 2.03bc
3,031d 3,112bc
3,055cd 3,046cd
2.57 2.55
2.65 2.57
TREATMENT
SEMD
29
0.035
45
0.106
Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
*** ** NS NS NS NS NS
*** *** NS * NS NS NS
** NS NS NS NS NS NS
NS NS NS NS NS NS NS
ACAR ET AL.: FEED RESTRICTION AND LYSINE
TABLE 4. Effect of dietary lysine on the live performance of broilers subjected to early feed restriction and cool temperaturesA
A
All values represent an average of 6 pens, each having approximately 36 birds. Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). C Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. D Standard error of the mean. *P < 0.05; **P < 0.01; ***P < 0.001; NS, P > 0.05. a–e Means within a column having different superscripts are significantly different (P < 0.05). B
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CARCASS YIELD Chilled carcass weights were significantly reduced by the early feed restriction (2,387 vs. 2,294 g). The percentage reduction in the chilled carcass weights was parallel to the reduction in live body weights (4%) due to the feed restriction. A significant interaction (P < 0.05) between feeding regimen and lysine level shows that (Table 5) chilled carcass yield of birds fed ad libitum was increased with increasing lysine, whereas yield was decreased in feedrestricted birds by increasing the lysine in the diets. Three-way interactions (P < 0.05) among treatments suggested that control birds fed ad libitum or restricted and birds in the cool temperature that were restricted-fed had reduced yields, whereas birds in the cool temperature fed ad libitum had significantly greater yield when fed HL. Feed-restricted birds were significantly (P < 0.05) fatter (7.9%) than the birds fed ad libitum (Table 5). The cool environment decreased the percentage abdominal fat of feed-restricted birds compared with those kept in the control environment. Although not significant for other comparisons, the trend was for cool temperatures to reduce percentage abdominal fat. A significant interaction (P < 0.05) between feeding regimen and dietary lysine suggested that abdominal fat pad was decreased (8.3%) in birds fed ad libitum and increased (4.3%) in feed-restricted birds when dietary lysine increased. On an absolute weight basis, early feed restriction significantly reduced (data not shown)
pectoralis major (447 vs. 430 g) and minor (124 vs. 119 g) muscles; however, this effect disappeared when the values were expressed as the percentage of chilled carcasses (Table 5). Although high lysine level had no impact on the percentage pectoralis major muscle, pectoralis minor muscle yield was increased (P < 0.05). Feed restriction and cool temperatures increased the percentage wings yield, whereas percentage drumsticks yield was increased by only control temperatures. Percentage thigh and “cage” were not impacted by any of the treatments (Table 6). Previous research suggests that increased lysine in diets improved feed efficiency and breast meat yield and decreased the percentage of carcass fat in high meat yielding broilers [19, 20], whereas live body weights remained unaffected. An attempt was made herein to alleviate a possible loss in breast yield resulting from feed restriction [6] by increasing lysine concentration in grower and finisher diets. Plavnik and Hurwitz [21] indicated that the lysine requirement for normal growth was increased as a result of feed restriction. However, final body weights and chilled carcass yield did not benefit from increasing dietary lysine after early feed restriction in the present study. Among the parts, only percentage pectoralis minor muscle benefited from high lysine in the grower and finisher diets, which partially confirmed our hypothesis because percentage yield of pectoralis major muscle remained unchanged. Jones and Farrell [17] found no conclusive results at 49 d of age when the early feed-restricted birds received supplemental lysine and methionine in the finisher diet. Feed restriction resulted in fatter birds when compared with birds fed ad libitum in the present study, agreeing with previous reports [6, 10, 16, 18, 22, 23]. Higher lysine levels produced less abdominal fat pad in birds fed ad libitum, which agreed with the study reported by Acar et al. [20]. However, although the opposite was true for the feed-restricted birds, it is not clear at this point why higher lysine levels in the grower and finisher diets produced a larger abdominal fat pad. MORTALITY Mortality from hatch to 21 d of age was negligible (1%). Actual average temperature in
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observed a 4 and 10% decrease in body weight when the duration of the feed restriction was 4 and 6 d, respectively, compared with birds fed ad libitum. Deaton [18] reported that male broilers had reduced growth by 8% by restricting feed intake 10% between 7 and 14 d of age. However, 25 to 40% feed intake restriction resulted in about 18% or greater reduction in body weight at 14 d, and these birds did not fully compensate by 41 d of age. In the present study, relative growth was accelerated in feedrestricted birds; however, it was not sufficient to equalize final body weights by 56 d of age between feed-restricted birds and birds fed ad libitum.
CHILLED CARCASSB
ABDOMINAL FAT PADB
PECTORALIS MAJORC
PECTORALIS MINORC
57 d
57 d
57 d
57 d
TEMPERATURE EFFECT
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Ad libitum
Control Cool
73.77ab 73.12bc
73.53bc 74.48a
2.06ab 1.89bc
1.81c 1.81c
18.06b 19.35a
18.27b 19.13a
5.30ab 4.96d
5.23ab 5.26ab
Restricted
Control Cool
73.06bc 74.07ab
72.86cd 73.22bc
2.11a 1.91b
2.16a 2.04ab
18.39b 19.18a
18.25b 19.13a
5.13bc 5.03cd
5.39a 5.31a
TREATMENT
SEMF Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
0.335
0.091
0.239
0.112
NS NS NS NS * NS *
* NS NS NS * NS NS
NS *** NS NS NS NS NS
NS NS NS * NS NS NS
ACAR ET AL.: FEED RESTRICTION AND LYSINE
TABLE 5. Effect of dietary lysine on the carcass characteristics of broilers subjected to early feed restriction and cool temperatures (%)A
A
All values represent the average of 5 birds of a pen of 36 birds. Chilled carcasses and abdominal fat pad were expressed relative to live weights at 56 d. Pectoralis major and minor were expressed relative to chilled carcass weights. D Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). E Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. F Standard error of the means. *P < 0.05; ***P < 0.001; NS, P > 0.05. a–d Means within a column having different superscripts are significantly different (P < 0.05). B C
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TABLE 6. Effect of dietary lysine on the carcass characteristics of broilers subjected to early feed restriction and cool temperatures (%)A WINGSB
DRUMSTICKSB
THIGH MEATB
CAGEB
57 Days
57 Days
57 Days
57 Days
TEMPERATURE EFFECT
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Ad libitum
Control Cool
11.48bc 11.65ab
11.45c 11.67ab
14.32a 13.85c
14.26ab 13.98bc
17.99 17.60
18.38 18.59
32.18 32.30
32.14 30.97
Restricted
Control Cool
11.72ab 11.84a
11.55bc 11.80a
14.26ab 13.99bc
14.25ab 13.94c
17.95 18.06
18.19 18.01
32.00 31.64
31.98 31.38
TREATMENT
0.119
0.154
0.303
0.376
* * NS NS NS NS NS
NS ** NS NS NS NS NS
NS NS NS NS NS NS NS
NS NS NS NS NS NS NS
A
All values represent the average of 5 birds of a pen of 36 birds. Wings, drumsticks, thigh meat, and “cage” were expressed relative to chilled carcass weights. C Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). D Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. E Standard error of the means. *P < 0.05; **P < 0.01; NS, P > 0.05. a–c Means within a column having different superscripts are significantly different (P < 0.05). B
TABLE 7. Effect of dietary lysine on the total and ascitic mortality of broilers subjected to early feed restriction and cool temperatures (%) TOTAL MORTALITY
ASCITIC MORTALITY
TEMPERATURE EFFECT
Normal lysineA
High lysineB
Normal lysineA
High lysineB
Ad libitum
Control Cool
8.57c 12.08b
5.12def 15.78a
2.25cd 7.01b
1.39d 10.21a
Restricted
Control Cool
3.24f 6.46cde
0.93d 1.42d
0.46d 3.71c
TREATMENT
SEMC Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L A
4.61ef 7.60cd 1.882
1.388
*** *** NS NS NS NS NS
** *** 0.076 NS NS 0.080 NS
Both growth and finisher diets contained NRC [11] recommendation levels (1.00 and 0.85%, respectively). Both growth and finisher diets contained 1.15 and 1.00% lysine, respectively. Standard error of the means. **P < 0.01; ***P < 0.001; NS, P > 0.05. a–f Means within a column having different superscripts are significantly different (P < 0.05). B C
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SEME Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
ACAR ET AL.: FEED RESTRICTION AND LYSINE
ing that the cool model induces ascites. A nonsignificant interaction (P = 0.076) between feeding regimen and temperature suggested that the increase in the ascitic mortality due to the cool environment was more drastic in the birds fed ad libitum compared with the feed-restricted birds. Another nonsignificant interaction (P = 0.08) between the temperature and lysine suggested that the ascitic mortality was decreased by the additional dietary lysine in control environment, whereas it was exacerbated (40%) by the additional dietary lysine in the cool environment. Lott et al. [24] reported that increased lysine levels did not contribute to ascites mortality, whereas Kerr et al. [25] agreed with the current findings indicating that increased dietary lysine increased the overall mortality.
CONCLUSIONS AND APPLICATIONS 1. Using the method described, it has been clearly shown that feed-restricted modern commercial broilers do not show complete “catch-up” growth by 56 d. Lysine did not have any beneficial effect on the final body weights and feed conversions. 2. In parallel with final body weights, chilled carcass weights of feed-restricted birds were 4% behind the birds fed ad libitum. 3. Feed restriction resulted in fatter birds. Additional dietary lysine decreased the fat in the birds fed ad libitum, whereas it increased the fat in the feed-restricted birds. 4. Although feed restriction decreased p. major and minor muscles significantly on an actual weight basis, lysine improved the deficit in the muscle reduction due to the feed restriction in the p. minor muscle but not in the p. major muscle. 5. Total mortality was decreased by the early feed restriction. Ascitic mortality was elevated in the cool environment compared with the control environment, confirming that the cool model is effective. Increased dietary lysine levels resulted in a greater susceptibility to ascites in cool temperatures.
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3. Odom, T.W., 1993. Ascites syndrome: Overview and update. Poult. Dig. 50:14–22.
7. van Harn, J., and T. Fabri, 1995. Voersturing bij vleeskuikens: Minder uitval, minder filet. Praktijkonderzoek Pluimveehouderij 2:14–17.
4. Shlosberg, A., E. Berman, U. Bendheim, and I. Plavnik, 1991. Controlled early feed restriction as a potential means of reducing the incidence of ascites in broilers. Avian Dis. 35:681–684.
8. Beane, W.L., J.A. Cherry, and W.D. Weaver, Jr., 1979. Intermittent light and restricted feeding of broiler chickens. Poultry Sci. 58:567–571.
5. Arce, J., M. Berger, and C.L. Coello, 1992. Control of ascites syndrome by feed restriction techniques. J. Appl. Poult. Res. 1:1–5.
9. Summers, J.D., D. Spratt, and J.L. Atkinson, 1990. Restricted feeding and compensatory growth for broilers. Poult. Sci. 69:1855–1861.
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the cool room was 14.3°C and control room was 23°C between 14 and 56 d. From 21 to 56 d of age (Table 7), feed restriction did, in fact, decrease the total percentage mortality by 47% (10.39 vs. 5.48% of mortality with birds fed ad libitum and feed-restricted birds, respectively). Fontana et al. [22] reported that mortality was significantly reduced by the early feed restriction. A significant (P < 0.001) temperature effect shows that there was a greater incidence of mortality in the cool environment (10.48%) than in the control environment (5.38%). There was no overall lysine effect on the total mortality. When the ascitic mortality was partitioned from the total mortality, significant effects were observed for feed and temperature. Feed restriction reduced the ascitic mortality, whereas ascitic mortality was greater in the cool environment than in the control environment, confirm-
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220 10. Yu, M.W., F.E. Robinson, M.T. Cladinin, and L. Bodnar, 1990. Growth and composition of broiler chickens in response to different regimes of feed restriction. Poult. Sci. 69:2074–2081. 11. National Research Council, 1984. Nutrient requirements of poultry. 8th. rev. ed. National Academy Press, Washington, DC. 12. SAS Institute, 1994. SAS/STAT User’s Guide. Release 6.08 Edition. SAS Institute Inc., Cary, NC. 13. Steel, R.G.D., and J.H. Torrie, 1980. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York, NY. 14. Snedecor, G.W., and W.G. Cochran, 1967. Statistical Methods. 6th ed. Iowa State University Press, Ames, IA. 15. Plavnik, I., and S. Hurwitz, 1985. The performance of broilers chicks during and following a severe feed restriction at an early age. Poult. Sci. 64:348–355. 16. Sizemore, F.G., 1994. Genetics of growth and development in chickens from different lines subjected to neonatal feed restriction. Ph.D. Dissertation. The Pennsylvania State University, University Park, PA.
18. Deaton, J. W., 1995. The effect of early feed restriction on broiler performance. Poult. Sci. 74:1280–1286. 19. Moran, E.T., Jr., and S.F. Bilgili, 1990. Processing losses, carcass quality and meat yield of broiler chickens as influenced by dietary lysine. Poult. Sci. 69:702–709.
20. Acar, N., E.T. Moran, Jr., and S.F. Bilgili, 1991. Live performance and carcass yield of male broilers from two commercial strain crosses receiving rations containing lysine below and above the established requirement between six and eight weeks of age. Poult. Sci. 70:2315–2321. 21. Plavnik, I., and S. Hurwitz, 1989. Effect of dietary protein, energy and feed pelleting on the response of chicks to early feed restriction. Poult. Sci. 68:1118–1125. 22. Fontana, E., W.D. Weaver, Jr., B.A. Watkins, and D.N. Denbow, 1992. Effect of early feed restriction on growth, feed conversion, and mortality in broilers chickens. Poult. Sci. 71:1296–1305. 23. Sizemore, F. G., and H.S. Siegel, 1993. Growth, feed conversion, and carcass composition in females of four broiler crosses fed starter diets with different energy levels and energy to protein ratios. Poult. Sci. 72:2216–2228. 24. Lott, B.D., S.L. Branton, and J.D. May, 1997. Dietary lysine and ascites incidence. J. Appl. Poult. Res. 6:331–334. 25. Kerr, B.J., M.T. Kidd, K.M. Halpin, G.W. McWard, and C.L. Quarles, 1999. Lysine level increase live performance and breast yield in male broilers. J. Appl. Poult. Res. 8:381–390.
ACKNOWLEDGMENTS Authors express their gratitude to Carol and William Crouch, Eric Lorenz, Dirk Wise, Gillian R. Leach, and Candace L. Kerr for their technical help. We greatly appreciate the support by Heartland Lysine Inc. for providing the lysine hydrochloride for this research.
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17. Jones, G.P.D., and D.J. Farrell, 1992. Early-life food restriction of broiler chickens 1. methods of application, amino acid supplementation and the age at which restrictions should commence. Br. Poult. Sci. 33:579–587.
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EFFECT OF DIETARY LYSINE ON YIELD LOSSES OCCURRING DURING EARLY FEED RESTRICTION TO REDUCE ASCITES N. ACAR1, R. M. HULET, and G. F. BARBATO Department of Poultry Science, The Pennsylvania State University, University Park, Pennsylvania 16802 Phone: (814) 863-8960 FAX: (814) 865-5691 e-mail: [email protected]
SUMMARY This study evaluated additions of dietary lysine to restore yield losses from feed restriction to reduce ascites. Feed restriction was used to limit daily feed intake of the birds to 75% of the metabolizable energy required for normal growth, based on the ad libitum intake of the birds. Grower and finisher diets contained normal lysine (NL) or high lysine (HL). Final body weight of feed-restricted birds was 96% of birds fed ad libitum, indicating that “catch-up” growth was not sufficient to equalize the body weights by 56 d of age between birds on feed restriction and those fed ad libitum. Feed-restricted birds were fatter than those birds fed ad libitum. HL reduced the deficit in the percentage pectoralis minor muscle yield compared with birds fed NL diets, whereas the percentage yield of pectoralis major muscle remained unaffected by dietary lysine. Feed restriction reduced the total ascitic mortality in the cool and control environments. It was concluded that increased lysine did not have any beneficial effect on the final body weight, percentage carcass yield, or any of the carcass characteristics, with the exception of pectoralis minor muscle yield, which was increased when birds were fed HL. Key words: Ascites, broilers, carcass yield, feed restriction, live performance, lysine 2001 J. Appl. Poult. Res. 10:211–220
DESCRIPTION OF PROBLEM Ascites is characterized by an accumulation of fluid in the abdominal cavity of affected birds followed by death [1]. When broiler chickens are selected for increased growth rate and meat yield, metabolic disorders, such as ascites, often accompany the rapid growth. Olkowski et al. [2] have indicated that ascites has become a major economic concern in the broiler industry worldwide. Odom [3] reported that economic losses due to ascites in the United 1
To whom correspondence should be addressed.
States have been estimated to exceed $100 million dollars annually. Feed restriction regimens at early ages reduce ascites mortality [4, 5, 6] by slowing the early growth of lean muscle [7]. In our laboratory, ascites has been successfully induced with a “cool model” [4], and the incidence of ascites has been reduced by restricting the feed (growth) to 75% of that ad libitum between 4 and 11 d posthatching [6]. However, early feed restriction results in birds having significantly smaller body weights at a given age than birds
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Primary Audience: Nutritionists, Poultry Producers
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212 fed ad libitum. Further, some early feed-restricted birds tend to have larger abdominal fat pads [8, 9, 10]. Acar et al. [6] also found a breast yield loss due to feed restriction, agreeing with reports by van Harn and Fabri [7]. Our objective in the present study was to determine if muscle-augmenting nutritional strategies of increased dietary lysine would impact breast yield or influence ascites susceptibility.
“COOL MODEL” TO INDUCE ASCITES
MATERIALS AND METHODS
CARCASS YIELD
From Days 14 through 56, birds were exposed to cool temperatures in one room to induce ascites. To obtain this temperature, the thermostat was set for 13°C, and the ventilation controller opened inlets for cool winter air or called for supplemental heat. The experiment was conducted between October and December.
FEED RESTRICTION PROGRAM
MORTALITY
All birds were provided a common starter diet (3,200 kcal/kg metabolizable energy, 23.0% CP, and 1.2% lysine) from 1 to 4 d of age. The feed restriction protocol was used to limit daily feed intake of the birds to 75% of the metabolizable energy required for normal growth of birds fed ad libitum from 4 to 11 d of age. Thereafter, the diet was provided for consumption ad libitum. Restricted-fed birds and birds fed ad libitum were weighed, and feed consumption of birds fed ad libitum was measured daily to calculate the daily allowance of the feed-restricted birds [6]. After feed restriction, the body weights of chicks and feed consumption were recorded weekly for each pen. Commercially mixed grower (3,195 kcal/ kg metabolizable energy and 20% CP from 22 to 42 d of age) and finisher (3,190 kcal/kg metabolizable energy and 18% CP from 43 to 56 d of age) diets contained normal lysine (NL; 1.00 and 0.85%) [NRC, 11] or high lysine (HL; 1.15 and 1.00%), respectively.
Dead birds were recorded and examined for gross lesions of ascites, such as amber-colored fluid in the abdominal cavity and in pericardium and enlarged heart and right ventricle. All data were subjected to statistical analysis [12, 13, 14, 15]. STATISTICAL ANALYSIS The data were analyzed by analysis of variance by using the general linear models procedure of SAS software [12]. From 1 to 21 d of age, feed restriction vs. ad libitum feed treatments (feeding regimen effect) and cool vs. control treatments (temperature effect) were compared (two-way ANOVA). From 22 to 56 d of age, dietary lysine effect was added into the model (three-way ANOVA). Tukey’s multiple comparison was performed when F test was significant [13]. Mortality data were analyzed by weighted ANOVA after arc sine square root percentage transformations [14].
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A total of 1,776 1-d-old male broilers of a commercial strain cross were wing-banded and placed in two identical rooms in an environmentally controlled house. Treatments within each room were feeding regimen (ad libitum vs. feed restriction) and dietary lysine (NRC [11] normal lysine levels vs. high lysine). Within each room, feeding regimen and lysine treatments were replicated six times for a total of 48 floor pens. Lighting was continuous. Birds were vaccinated for Marek’s disease at hatch.
Five birds from each pen were randomly selected and processed according to commercial practices at 56 d of the experiment. Fat pads were removed from the abdominal cavity and weighed. Carcasses were chilled in the slush ice overnight. The next day, chilled carcasses were hung on the lines to let the water drip for approximately 5 min. Carcasses were cut into the following pieces and then weighed: wings, drumsticks, breast fillet (pectoralis major muscle), tenders (pectoralis minor muscle), thigh meat, and “cage” (remaining ribcage, skin and fat).
BIRDS AND HOUSING
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TABLE 1. Composition of experimental diets (% of diet) GROWER INGREDIENT
Calculated composition Metabolizable energy, kcal/kg Crude protein, % Lysine, % Methionine, % Cystine, % Analyzed compositionF Crude protein, % Lysine, % Methionine, % Cystine, %
Normal lysine 68.22 20.30 5.00 ... 2.50 2.00 0.259 1.102 0.30 0.024 0.033 0.13 0.25 100.001
A
High lysine 68.15 19.85 5.00 ... 2.50 2.35 0.261 1.105 0.30 0.021 0.196 0.13 0.25 99.996
FINISHER
FINISHER A
Normal lysine 71.47 14.95 4.50 5.00 2.205 0.35 ... 0.972 0.30 0.002 ... ... 0.25 99.999
High lysineA 70.63 15.30 4.45 5.45 2.50 ... ... 0.975 0.30 0.004 0.141 ... 0.25 100.000
3,195 20.00 1.00 0.38 0.35
3,195 20.00 1.15 0.38 0.35
3,190 18.00 0.85 0.32 0.33
3,190 18.00 1.00 0.32 0.33
19.98 0.96 0.35 0.34
19.96 1.11 0.35 0.35
18.01 0.82 0.29 0.33
17.99 0.93 0.32 0.34
Grower diet formulated to contain normal levels of lysine (NL) = (1.0%) or high lysine (HL) = (1.15%); finisher diet contained normal lysine levels (NL), 0.85% or high lysine (HL), 1.00%. Contained 16% Ca and 21% available P. C Contained 38% Ca. D Amprolium (Amprol 25%), Merck & Co., Inc., Rahway, NJ 07065-0912. E Supplied the following per kilogram of vitamin and mineral premix: Vitamin A, 2,640,000 IU (retinyl acetate); cholecalciferol, 880,000 ICU; vitamin E, 6,600 IU (dl-α-tocopherol acetate); menadione, 660 mg; thiamine, 440 mg; riboflavine, 1,760 mg; niacin, 13,200 mg; pantothenic acid, 3,080 mg; pyridoxine, 660 mg; folic acid, 220 mg; biotin, 22 mg; vitamin B12, 3,520 µg; manganese, 26,400 mg; zinc, 22,000 mg; iron, 11,000 mg; copper, 1,760 mg; iodine, 220 mg. F Amino acid analysis of the diets was done by Degussa Corp., Allendale, NJ 07401. A B
RESULTS AND DISCUSSION LIVE PERFORMANCE Analyzed crude protein and calculated energy levels of the diets met the NRC [11] requirements for broilers. Actual lysine levels for the experimental diets (both grower and finisher diets) were from 0.03 to 0.07% lower than the initial formulation (Table 1). Broilers had equal body weights at hatch (49 g) and at 4 d of age (P > 0.05). Feed restriction significantly reduced the body weight and feed intake and increased the feed conversion of the birds from 4 to 11 d of age (Table 2).
At 11 d, body weight of feed-restricted birds was 66% of that of the birds fed ad libitum. Upon realimentation, weight gain was significantly higher (119 vs. 113 g) and feed conversion was better for the feed-restricted birds at 11 to 14 d of age than for the birds fed ad libitum, whereas at 14 d, body weights of feedrestricted birds were 78% of those of the birds fed ad libitum. At 14 d of age, half of the birds were exposed to the cool temperatures to induce ascites. Body weights were reduced by the cool temperatures for both groups of birds; feed-restricted birds weighed up to 85% of the 21-d body weights of birds fed ad libitum (Table 3). Feed
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Ground corn Soybean meal (48% CP) Animal by-product (65% CP) Canola meal Blended fat (8,140 kcal/kg, ME) Corn gluten meal (60% CP) Mono/dicalcium phosphateB LimestoneC Salt DL-Methionine L-LysineⴢHCl CoccidiostatD Vitamin-trace mineralsE Total
GROWER A
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TABLE 2. Live performance of broilers subjected to early feed restrictionA FEED CONVERSION (g feed intake/g weight gain)
BODY WEIGHT (g) TREATMENT Ad libitum Restricted SEMB Significance
4d
11 d
94 94
263 173
0.36 NS
0.86 ***
14 d 376 292 1.20 ***
4–11 d
11–14 d
1.47 1.76
1.48 1.29
0.007 ***
0.011 ***
conversion was better for the restricted birds than the birds fed ad libitum; cool temperatures increased feed conversion significantly (P < 0.01). At 42 d, body weights of feed-restricted birds were 96% of those of the birds fed ad libitum (2,043 vs. 2,128 g). A significant lysine effect indicated that feed conversion was improved for the HL birds when compared to the NL fed birds (2.00 vs. 2.06). Feed conversion was poorer for the birds in the cool environment (2.08 vs. 1.98) than in the control environment, whereas feed-restricted birds had lower feed conversions than the birds fed ad libitum. At 56 d of age, feed-restricted birds did not attain the same body weights as the control birds (3,172 vs. 3,061 g), whereas there were no treatment differences in feed conversions (Table 4).
Early feed-restriction regimens can be used as a management tool to reduce ascitic mortality in rapidly growing broiler chickens [4, 5, 6]. Upon realimentation, birds presumably recover from the growth deficit resulting from limited nutrient intake during feed restriction. This recovery is based on severity and length of feed restriction. According to Plavnik and Hurwitz [15] birds fully compensated for the weight loss when grown to 8 wk after early feed restriction and had improved feed conversion. However, studies using faster-growing or high-yielding contemporary commercial strains of broilers [6, 10] did not achieve complete “catch-up” growth by 7 or 8 wk of age, respectively. It is possible that this finding was attributable to genetic differences [16] and severity of the feed restriction relative to the growth. Jones and Farrell [17]
TABLE 3. Live performance of broilers subjected to early feed restriction and cool temperaturesA (21 d of age) TREATMENT
TEMPERATURE EFFECT
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
Ad libitum
Control Cool
723a 676b
1.47b 1.53c
Restricted
Control Cool
606c 582d
1.40a 1.44b
SEMB Significance Feeding regimen (F) Temperature (T) F×T A
6.2 *** *** *
All values represent the average of 12 pens each having 36 birds. Standard error of the mean. *P < 0.05; **P < 0.01; ***P < 0.001; NS, P > 0.05. a–c Means within a column having different superscripts are significantly different (P < 0.05). B
0.014 *** ** NS
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A All values represent the average of 24 pens, each having 36 birds. Average chick weight at 1 d of age was 49 g for all treatments. B Standard error of the mean. ***P < 0.001; NS, P > 0.05.
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
BODY WEIGHT (g)
FEED CONVERSION (g feed intake/g weight gain)
42 d
21–42 d
56 d
42–56 d
TEMPERATURE EFFECT
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Normal lysineB
High lysineC
Ad libitum
Control Cool
2,164a 2,071bc
2,178a 2,098b
2.06cd 2.17e
2.00b 2.09d
3,158ab 3,181ab
3,167ab 3,182
2.57 2.47
2.56 2.40
Restricted
Control Cool
2,033cd 2,023d
2,107b 2,008d
1.97b 2.03bc
1.88a 2.03bc
3,031d 3,112bc
3,055cd 3,046cd
2.57 2.55
2.65 2.57
TREATMENT
SEMD
29
0.035
45
0.106
Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
*** ** NS NS NS NS NS
*** *** NS * NS NS NS
** NS NS NS NS NS NS
NS NS NS NS NS NS NS
ACAR ET AL.: FEED RESTRICTION AND LYSINE
TABLE 4. Effect of dietary lysine on the live performance of broilers subjected to early feed restriction and cool temperaturesA
A
All values represent an average of 6 pens, each having approximately 36 birds. Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). C Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. D Standard error of the mean. *P < 0.05; **P < 0.01; ***P < 0.001; NS, P > 0.05. a–e Means within a column having different superscripts are significantly different (P < 0.05). B
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CARCASS YIELD Chilled carcass weights were significantly reduced by the early feed restriction (2,387 vs. 2,294 g). The percentage reduction in the chilled carcass weights was parallel to the reduction in live body weights (4%) due to the feed restriction. A significant interaction (P < 0.05) between feeding regimen and lysine level shows that (Table 5) chilled carcass yield of birds fed ad libitum was increased with increasing lysine, whereas yield was decreased in feedrestricted birds by increasing the lysine in the diets. Three-way interactions (P < 0.05) among treatments suggested that control birds fed ad libitum or restricted and birds in the cool temperature that were restricted-fed had reduced yields, whereas birds in the cool temperature fed ad libitum had significantly greater yield when fed HL. Feed-restricted birds were significantly (P < 0.05) fatter (7.9%) than the birds fed ad libitum (Table 5). The cool environment decreased the percentage abdominal fat of feed-restricted birds compared with those kept in the control environment. Although not significant for other comparisons, the trend was for cool temperatures to reduce percentage abdominal fat. A significant interaction (P < 0.05) between feeding regimen and dietary lysine suggested that abdominal fat pad was decreased (8.3%) in birds fed ad libitum and increased (4.3%) in feed-restricted birds when dietary lysine increased. On an absolute weight basis, early feed restriction significantly reduced (data not shown)
pectoralis major (447 vs. 430 g) and minor (124 vs. 119 g) muscles; however, this effect disappeared when the values were expressed as the percentage of chilled carcasses (Table 5). Although high lysine level had no impact on the percentage pectoralis major muscle, pectoralis minor muscle yield was increased (P < 0.05). Feed restriction and cool temperatures increased the percentage wings yield, whereas percentage drumsticks yield was increased by only control temperatures. Percentage thigh and “cage” were not impacted by any of the treatments (Table 6). Previous research suggests that increased lysine in diets improved feed efficiency and breast meat yield and decreased the percentage of carcass fat in high meat yielding broilers [19, 20], whereas live body weights remained unaffected. An attempt was made herein to alleviate a possible loss in breast yield resulting from feed restriction [6] by increasing lysine concentration in grower and finisher diets. Plavnik and Hurwitz [21] indicated that the lysine requirement for normal growth was increased as a result of feed restriction. However, final body weights and chilled carcass yield did not benefit from increasing dietary lysine after early feed restriction in the present study. Among the parts, only percentage pectoralis minor muscle benefited from high lysine in the grower and finisher diets, which partially confirmed our hypothesis because percentage yield of pectoralis major muscle remained unchanged. Jones and Farrell [17] found no conclusive results at 49 d of age when the early feed-restricted birds received supplemental lysine and methionine in the finisher diet. Feed restriction resulted in fatter birds when compared with birds fed ad libitum in the present study, agreeing with previous reports [6, 10, 16, 18, 22, 23]. Higher lysine levels produced less abdominal fat pad in birds fed ad libitum, which agreed with the study reported by Acar et al. [20]. However, although the opposite was true for the feed-restricted birds, it is not clear at this point why higher lysine levels in the grower and finisher diets produced a larger abdominal fat pad. MORTALITY Mortality from hatch to 21 d of age was negligible (1%). Actual average temperature in
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observed a 4 and 10% decrease in body weight when the duration of the feed restriction was 4 and 6 d, respectively, compared with birds fed ad libitum. Deaton [18] reported that male broilers had reduced growth by 8% by restricting feed intake 10% between 7 and 14 d of age. However, 25 to 40% feed intake restriction resulted in about 18% or greater reduction in body weight at 14 d, and these birds did not fully compensate by 41 d of age. In the present study, relative growth was accelerated in feedrestricted birds; however, it was not sufficient to equalize final body weights by 56 d of age between feed-restricted birds and birds fed ad libitum.
CHILLED CARCASSB
ABDOMINAL FAT PADB
PECTORALIS MAJORC
PECTORALIS MINORC
57 d
57 d
57 d
57 d
TEMPERATURE EFFECT
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Normal lysineD
High lysineE
Ad libitum
Control Cool
73.77ab 73.12bc
73.53bc 74.48a
2.06ab 1.89bc
1.81c 1.81c
18.06b 19.35a
18.27b 19.13a
5.30ab 4.96d
5.23ab 5.26ab
Restricted
Control Cool
73.06bc 74.07ab
72.86cd 73.22bc
2.11a 1.91b
2.16a 2.04ab
18.39b 19.18a
18.25b 19.13a
5.13bc 5.03cd
5.39a 5.31a
TREATMENT
SEMF Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
0.335
0.091
0.239
0.112
NS NS NS NS * NS *
* NS NS NS * NS NS
NS *** NS NS NS NS NS
NS NS NS * NS NS NS
ACAR ET AL.: FEED RESTRICTION AND LYSINE
TABLE 5. Effect of dietary lysine on the carcass characteristics of broilers subjected to early feed restriction and cool temperatures (%)A
A
All values represent the average of 5 birds of a pen of 36 birds. Chilled carcasses and abdominal fat pad were expressed relative to live weights at 56 d. Pectoralis major and minor were expressed relative to chilled carcass weights. D Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). E Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. F Standard error of the means. *P < 0.05; ***P < 0.001; NS, P > 0.05. a–d Means within a column having different superscripts are significantly different (P < 0.05). B C
217
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TABLE 6. Effect of dietary lysine on the carcass characteristics of broilers subjected to early feed restriction and cool temperatures (%)A WINGSB
DRUMSTICKSB
THIGH MEATB
CAGEB
57 Days
57 Days
57 Days
57 Days
TEMPERATURE EFFECT
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Normal lysineC
High lysineD
Ad libitum
Control Cool
11.48bc 11.65ab
11.45c 11.67ab
14.32a 13.85c
14.26ab 13.98bc
17.99 17.60
18.38 18.59
32.18 32.30
32.14 30.97
Restricted
Control Cool
11.72ab 11.84a
11.55bc 11.80a
14.26ab 13.99bc
14.25ab 13.94c
17.95 18.06
18.19 18.01
32.00 31.64
31.98 31.38
TREATMENT
0.119
0.154
0.303
0.376
* * NS NS NS NS NS
NS ** NS NS NS NS NS
NS NS NS NS NS NS NS
NS NS NS NS NS NS NS
A
All values represent the average of 5 birds of a pen of 36 birds. Wings, drumsticks, thigh meat, and “cage” were expressed relative to chilled carcass weights. C Grower and finisher diets contained NRC [11] recommended levels (1.00 and 0.85%, respectively). D Grower and finisher diets contained 1.15 and 1.00% lysine, respectively. E Standard error of the means. *P < 0.05; **P < 0.01; NS, P > 0.05. a–c Means within a column having different superscripts are significantly different (P < 0.05). B
TABLE 7. Effect of dietary lysine on the total and ascitic mortality of broilers subjected to early feed restriction and cool temperatures (%) TOTAL MORTALITY
ASCITIC MORTALITY
TEMPERATURE EFFECT
Normal lysineA
High lysineB
Normal lysineA
High lysineB
Ad libitum
Control Cool
8.57c 12.08b
5.12def 15.78a
2.25cd 7.01b
1.39d 10.21a
Restricted
Control Cool
3.24f 6.46cde
0.93d 1.42d
0.46d 3.71c
TREATMENT
SEMC Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L A
4.61ef 7.60cd 1.882
1.388
*** *** NS NS NS NS NS
** *** 0.076 NS NS 0.080 NS
Both growth and finisher diets contained NRC [11] recommendation levels (1.00 and 0.85%, respectively). Both growth and finisher diets contained 1.15 and 1.00% lysine, respectively. Standard error of the means. **P < 0.01; ***P < 0.001; NS, P > 0.05. a–f Means within a column having different superscripts are significantly different (P < 0.05). B C
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SEME Significance Feeding regimen (F) Temperature (T) F×T Lysine (L) F×L T×L F×T×L
ACAR ET AL.: FEED RESTRICTION AND LYSINE
ing that the cool model induces ascites. A nonsignificant interaction (P = 0.076) between feeding regimen and temperature suggested that the increase in the ascitic mortality due to the cool environment was more drastic in the birds fed ad libitum compared with the feed-restricted birds. Another nonsignificant interaction (P = 0.08) between the temperature and lysine suggested that the ascitic mortality was decreased by the additional dietary lysine in control environment, whereas it was exacerbated (40%) by the additional dietary lysine in the cool environment. Lott et al. [24] reported that increased lysine levels did not contribute to ascites mortality, whereas Kerr et al. [25] agreed with the current findings indicating that increased dietary lysine increased the overall mortality.
CONCLUSIONS AND APPLICATIONS 1. Using the method described, it has been clearly shown that feed-restricted modern commercial broilers do not show complete “catch-up” growth by 56 d. Lysine did not have any beneficial effect on the final body weights and feed conversions. 2. In parallel with final body weights, chilled carcass weights of feed-restricted birds were 4% behind the birds fed ad libitum. 3. Feed restriction resulted in fatter birds. Additional dietary lysine decreased the fat in the birds fed ad libitum, whereas it increased the fat in the feed-restricted birds. 4. Although feed restriction decreased p. major and minor muscles significantly on an actual weight basis, lysine improved the deficit in the muscle reduction due to the feed restriction in the p. minor muscle but not in the p. major muscle. 5. Total mortality was decreased by the early feed restriction. Ascitic mortality was elevated in the cool environment compared with the control environment, confirming that the cool model is effective. Increased dietary lysine levels resulted in a greater susceptibility to ascites in cool temperatures.
REFERENCES AND NOTES 1. Hall S.A., and N. Machicao, 1968. Myocarditis in broiler chickens reared at high altitude. Avian Dis. 12:75–84. 2. Olkowski, A.A., L. Kumor, and H.L. Classen, 1996. Changing epidemiology of ascites in broiler chickens. Can. J. Anim. Sci. 76:135–140.
6. Acar, N., G.F. Sizemore, G.R. Leach, R.F. Wideman, Jr., R.L. Owen, and G.F. Barbato, 1995. Growth of broiler chickens in response to feed restriction regimens to reduce ascites. Poultry Sci. 74:833–843.
3. Odom, T.W., 1993. Ascites syndrome: Overview and update. Poult. Dig. 50:14–22.
7. van Harn, J., and T. Fabri, 1995. Voersturing bij vleeskuikens: Minder uitval, minder filet. Praktijkonderzoek Pluimveehouderij 2:14–17.
4. Shlosberg, A., E. Berman, U. Bendheim, and I. Plavnik, 1991. Controlled early feed restriction as a potential means of reducing the incidence of ascites in broilers. Avian Dis. 35:681–684.
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the cool room was 14.3°C and control room was 23°C between 14 and 56 d. From 21 to 56 d of age (Table 7), feed restriction did, in fact, decrease the total percentage mortality by 47% (10.39 vs. 5.48% of mortality with birds fed ad libitum and feed-restricted birds, respectively). Fontana et al. [22] reported that mortality was significantly reduced by the early feed restriction. A significant (P < 0.001) temperature effect shows that there was a greater incidence of mortality in the cool environment (10.48%) than in the control environment (5.38%). There was no overall lysine effect on the total mortality. When the ascitic mortality was partitioned from the total mortality, significant effects were observed for feed and temperature. Feed restriction reduced the ascitic mortality, whereas ascitic mortality was greater in the cool environment than in the control environment, confirm-
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20. Acar, N., E.T. Moran, Jr., and S.F. Bilgili, 1991. Live performance and carcass yield of male broilers from two commercial strain crosses receiving rations containing lysine below and above the established requirement between six and eight weeks of age. Poult. Sci. 70:2315–2321. 21. Plavnik, I., and S. Hurwitz, 1989. Effect of dietary protein, energy and feed pelleting on the response of chicks to early feed restriction. Poult. Sci. 68:1118–1125. 22. Fontana, E., W.D. Weaver, Jr., B.A. Watkins, and D.N. Denbow, 1992. Effect of early feed restriction on growth, feed conversion, and mortality in broilers chickens. Poult. Sci. 71:1296–1305. 23. Sizemore, F. G., and H.S. Siegel, 1993. Growth, feed conversion, and carcass composition in females of four broiler crosses fed starter diets with different energy levels and energy to protein ratios. Poult. Sci. 72:2216–2228. 24. Lott, B.D., S.L. Branton, and J.D. May, 1997. Dietary lysine and ascites incidence. J. Appl. Poult. Res. 6:331–334. 25. Kerr, B.J., M.T. Kidd, K.M. Halpin, G.W. McWard, and C.L. Quarles, 1999. Lysine level increase live performance and breast yield in male broilers. J. Appl. Poult. Res. 8:381–390.
ACKNOWLEDGMENTS Authors express their gratitude to Carol and William Crouch, Eric Lorenz, Dirk Wise, Gillian R. Leach, and Candace L. Kerr for their technical help. We greatly appreciate the support by Heartland Lysine Inc. for providing the lysine hydrochloride for this research.
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