Effects of Feed Composition and Feeding Schedule on Growth and Development of Broiler Breeder Males1

Effects of Feed Composition and Feeding Schedule on Growth and Development of Broiler Breeder Males 1 P. D. VAUGHTERS, G. M. PESTI,2 and B. HOWARTH, JR. Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication February 3, 1986)

1987 Poultry Science 66:134-146 INTRODUCTION

MATERIALS AND METHODS

Many methods of restricted feeding of broiler breeders have been investigated as a means of improving reproductive performance by delaying sexual maturity and reducing body weight. Low protein diets were a satisfactory method to delay the sexual maturity of pullets raised for commercial egg production (Waldroup and Harms, 1962) and meat-type chick production (Waldroup et al., 1966; Harms et al., 1968), and White Leghorn males (Jones et al., 1967). The skip-a-day feeding program was suggested by Luckham et al. (1963) and by the Arbor Acres Review (Anonymous, 1965). This method of giving little or no feed on the off day was quickly adopted by the poultry industry without extensive or critical testing. The experiments reported here were conducted to study the effects of varied protein and energy levels and different feeding schedules on the growth and subsequent reproductive capacity of broiler breeder males.

Experiment 1. Seven hundred and twenty Hubbard White Mountain breeder cockerels were hatched March 10, 1983. They received vaccinations for Marek's, Newcastle, and bronchitis diseases and were dubbed and detoed at the hatchery. Thirty chicks were placed in each of 24 pens containing wood shavings. Birds received 24 hr artificial light the first 3 days and then natural daylength until the 28th day. The 15 and 20% protein starter diets (Table 1) were each fed to 12 replicate pens of males. At 28 days of age each bird was weighed individually, the length of the right shank was measured (top of the shank to the end of the middle toe), and the bird was transferred to a floor pen in a windowless house with 8 hr light/ day. Two grower diets containing 2.85 or 2.00 kcal metabolizable energy (ME)/g were fed either ad libitum, every other day (EOD), or every day (ED) to four replicate pens of 30 birds per treatment as shown in Table 1. Restricted feeding was based on a 15% protein and 2.85 kcal/g diet fed EOD as recommended by the Hubbard Management Guide (1983); both diets were fed on an equal ME intake basis. The ED and EOD-fed birds received the same amount of feed in each 2-day period. The amount of

'A preliminary presentation of part of this work was presented at the XVII World's Poultry Congress, Helsinki, Finland, August, 1984. 2 To whom correspondence should be addressed.

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ABSTRACT Two experiments were conducted to compare the effects of feeding broiler breeder males: 1) a 15 or 20% protein starter diet (0 to 4 weeks) and 2) varying levels of energy and protein on an every day (ED) or on an every other day (EOD) basis during the growing period (4 to 20 weeks). Weight gain and shank length at 28 days were less for males started on 15% protein in both experiments. In the first experiment, males fed diets containing 2.8 kcal metabolizable energy (ME)/g during the grower period weighed and gained more than those fed 2.0 kcal ME/g although total ME intake was the same. Males fed ED gained significantly more than those fed EOD. In the second experiment, males fed 15% protein during the grower period gained and weighed more than those fed 12 or 18% protein, and those fed 15% ED gained and weighed significantly more than those fed 20% EOD. In both experiments males fed ED were more feed efficient (as measured by gain/feed consumed) than males fed EOD but consuming the same amount of feed. Semen characteristics were not affected by feeding schedule or grower diet protein level. Fertility was higher in 3 of the 4 weeks sampled for males fed 15% ED. Results indicate that feeding schedule (ED vs. EOD) as well as nutrient intake influence body weight gains of broiler breeder males. (Key words: broiler breeders, restricted feeding, protein, metabolizable energy)

FEEDING BROILER BREEDER MALES

135

TABLE 1. Composition of basal diets fed in Experiment 1 Ingredient

Starter diets

Corn Soybean meal Oats, ground Wheat middlings Alfalfa meal Poultry oil Dicalcium phosphate Limestone Salt (NaCl) Vitamin premix 2 Mineral premix 3 DL-Methionine L-Lysine 60% Choline chloride Composition by calculation (National Research Council, 1984) Metabolizable energy, kcal/g Protein, % Methionine, % Methionine + cystine, % Methionine + cystine, % of protein Lysine, % Lysine, % of protein Calcium, % Phosphorus, % Sodium, % Chloride, %

58.11 26.52

63.70 12.62

11.65

19.85

1.45 1.41 .40 .25 .05 .17

1.43 1.49 .40 .25 .05 .10 .10 .02

2.85 20.00 .50 .82 4.1 1.06 5.3 .94 .70 .19 .28

2.85 15.00 .36 .61 4.1 .79 5.3 .94 .70 .20 .28

48.40 14.88 30.82 .50 2.64 2.04 .40 .25 .05 .01

2.85 15.00 .27 .52 3.5 .74 4.9 1.41 .81 .20 .30

15.00 3.39 25.72 51.62 .50 2.99 .40' .25 .05 .08

2.00 15.00 .30 .51 3.4 .65 4.3 1.41 .81 .24 .52

Salt was decreased to .2% after 2 weeks because of wet litter, making Na = .16% and CI = .24%.

2

Vitamin premix provides (per kg diet): vitamin A, 55,000 IU; vitamin D 3 , 1100 ICU; vitamin E, 11 IU; riboflavin, 4.4 mg; Ca pantothenate, 12 mg; nicotinic acid, 44 mg; choline Cl, 220 mg; vitamin B „ , 6.6 meg; vitamin B 6 , 2.2 mg; menadione, 1.1 mg; folic acid, .55 mg; d-biotin, .11 mg, thiamine 2.2 mg; ethoxyquin, 125 mg. 3

Mineral premix provides (ppm of diet): Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.05.

feed offered to restricted-fed birds was adjusted weekly to account for mortality and the entire flock was weighed by pen every 4 weeks to ensure adherence to the management guide target body weights. At 19 weeks each bird was individually weighed and the right shank was measured. During the growing period (4 to 19 weeks), birds were vaccinated for Newcastle disease, infectious bursal disease, laryngotracheitis, and fowl pox. Beaks were trimmed at 8 weeks of age. Light was increased 1 hr/week during the last 2 weeks. Experiment 2. Seven hundred and twenty Hubbard White Mountain breeder cockerels were hatched April 16, 1984. Brooding conditions were the same as in Experiment 1; starter diets were similar to those in Experiment 1 (Table 2). Each diet was fed to 12 pens of 30

chicks per treatment. At 28 days all birds were individually weighed and the right shank length was measured. Two birds per pen were killed and liver, heart, pancreas, intestine, testes, and left pectoralis major were weighed. The intestine was opened, rinsed of all feed, and blotted dry. Remaining birds were then transferred to floor pens in a windowless house and provided 10 hr/day artificial light. The experimental design was a 2 x 3 factorial design with two programs (15% starter with grower fed ED or 20% starter with grower fed EOD) and three grower diet protein levels (12, 15, or 18% (Table 2). Thus, there were four replicate pens of 28 chicks per treatment. Restricted feeding was based on 15% protein fed EOD as recommended by the Hubbard Management Guide (1983), and all diets were fed on an

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1

Grower diets

136

VAUGHTERS ET AL. TABLE 2. Composition of basal diets fed in Experiment 2 Grower diets

Ingredient

Starter diets

Corn Soybean meal Oats, ground Poultry oil Defluorinated phosphate Limestone Salt (NaCl) Vitamin premix 1 Mineral premix 2 Selenium premix 3 DL-Methionine Composition by calculat ion, National Research Council, 1984 Metabolizable energy, kcal/g Protein, % Methionine, % Methionine + cystine, % Methionine + cystine, % of protein Calcium, % Phosphorus, % Sodium, % Chloride, %

38.63 13.60 43.51 1.00 1.81 .65 .40 .25 .05 .05 .05

40.02 27.06 28.71 1.00 1.73 .65 .40 .25 .05 .05 .08

37.93 6.71 51.08 1.00 1.86 .65 .40 .25 .05 .05 .02

38.63 13.60 43.51 1.00 1.81 .65 .40 .25 .05 .05 .05

39.46 21.67 34.63 1.00 1.76 .65 .40 .25 .05 .05 .07

2.85 15.00 .30 .55 3.7 .90 .64 .29 .31

2.85 20.00 .40 .73 3.7 .90 .67 .28 .30

2.85 12.44 .24 .46 3.7 .90 .62 .30 .31

2.85 15.00 .30 .55 3.7 .90 .64 .29 .31

2.85 18.00 .36 .66 3.7 .90 .65 .28 .30

(ni)

'Mineral premix provides (ppm of diet): Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.05. 3

Selenium premix provides .1 mg/kg selenium as sodium selenate.

equal weight basis from this recommendation. The ED and EOD feeding method was identical to that used in Experiment 1. Vaccination and debeaking schedules were the same as in Experiment 1. Amount fed was adjustedd weekly to account for mortality. Birds were weighed by pen every 4 weeks. At 20 weeks each bird was individually weighed, the right shank was measured, and two birds per pen were killed for organ weight measurement. The procedures were the same as those used at 28 d. In addition, two birds per pen were bled via the brachial vein and tested for Gumboro antibody titers. Ten males per treatment were transferred to individual cages and fed a diet containing 17% protein and 2.975 kcal ME/g. Feeding levels followed the Hubbard Management Guide (1983). Lights were increased 1 hr/week to a maximum of 14 hr/day. Males were ejaculated by abdominal massage once per week until 24 weeks of age, at which time there was sufficient

semen to begin fertility and semen quality measurements. Thereafter birds were ejaculated on Mondays for fertility studies and on Wednesdays for semen quality studies. Fertility of males was determined by pooling semen from the 10 males in each treatment and artificially inseminating 15 laying Single Comb White Leghorn females. Eggs were collected daily and set once per week. Eggs were incubated for 7 days before candling for embryonic growth. Eggs appearing to be infertile were broken open and the germinal disc was examined macroscopically for development. Individual semen samples were obtained for measurements of semen volume and semen percent packed cell volume (PCV). Semen volume was measured in 1 cc plastic syringes graduated in increments of .01 cc. The PCV was determined by filling a microhematocrit tube with thoroughly mixed semen, centrifuging for 5 min (centrifuge model MB, International Equipment Company, Boston, MA), and measuring the

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'Vitamin premix provides (per kg diet): vitamin A, 55,000 IU; vitamin D 3 , 1100 ICU; vitamin E, 11 IU; riboflavin, 4.4 mg; Ca pantothenate, 12 mg, nicotinic acid, 44 mg; choline CI, 220 mg; vitamin B 1 2 , 6.6 Mg; vitamin B 6 , 2.2 mg; menadione, 1.1 mg; folic acid, .33 mg; d-biotin, .11 mg, thiamine 2.2 mg; ethoxyquin, 125 mg.

FEEDING BROILER BREEDER MALES TABLE 3. Effect of starting diet protein content on performance (0 to 27 days) of breeder males at 4 weeks (Experiment l)1 Dietary protein

Gain

Consumption

(%)

(kg)

(kg)

15

.59 ± . 0 1 a

1.31 ± .06 a

20

b

a

.73 ± , 0 2

1.32 + .04

Efficiency

.46 ± .02 a .56 + , 0 1 b

'Mean ± SE.

packed cell and fluid portion of the semen (Arscott and Kuhns, 1969). Statistical significance in both experiments was determined by analysis of variance and Duncan's new multiple range test (1955) using the general linear models procedure described in the SAS User's Guide (SAS Institute, 1979).

RESULTS

Experiment 1. Males started on the low protein (15%) diet gained less than those started on the high protein diet during the starter period, although they consumed an almost identical amount of feed (Table 3). Frame size, as indicated by shank length, was significantly less for chicks started on the low protein diet, even though the difference was small (5%; Table 4). There were no differences in uniformity in body weights or frame size between starter diets as indicated by within-pen coefficients of variation. Males fed the high energy grower diet (2.85 kcal/g) gained and weighed more than those fed

the low energy grower diet (Table 5). Males started on low protein diets gained and weighed more at 19 weeks than those started on high protein diets. The full-fed males gained and weighed nearly twice that of those fed by the other two schedules at 19 weeks. There was a smaller, consistent, and significant difference between males fed ED and those fed EOD. The males fed ED gained more than those fed EOD on nearly identical amounts of feed. Shank length at 19 days was not influenced by starter diet, but males fed the high energy grower diet and those full fed had longer shanks than the others (Table 6). However, only full feeding altered within-pen variability of body weights and shank length at 19 weeks of age. Variability in body weight was decreased (birds were all quite large), but variability in shank length was not affected (Table 7). Mortality did not appear to be influenced by starter diet protein, grower diet energy, or feeding schedules. There were significant interactions beween growing diet and feeding schedule for several dependent variables (Table 8). This resulted from the large increase in body weight gain of the full-fed birds receiving the high vs. low energy diet. There was a difference between high and low energy diets for restricted birds, but it was much smaller in magnitude than with the full-fed birds. Experiment 2. During the brooding period, males started on the low protein (15%) starter diet gained less and consumed significantly less feed than those started on a high protein diet (Table 9). Shank length was smaller for those birds started on low protein, but within pen coefficients of variation indicated less variability in body weights and shank length on the 20% protein starter diet (Table 10). The left pectoralis major was larger in males fed the high protein

TABLE 4. Body weight and shank length means and coefficients of variation of 4 week-old breeder males fed two starter diet protein levels ad libitum (Experiment l)1 Dietary protein

Shank length

Body weight Mean

Mean

CV

CV

,

(%) 15

.63 ± .008 b

20

a

.76 ± .015

C
(>-m) 15.5 + . 5 a

11.1 ± . l b

5.7±.8a

a

a

4.8±.2a

15.7 + l . l

11.7 ± . l

a ' b Values with different superscripts within columns are significantly different (P<.05). 1

Values ± SE.

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Values with different superscripts within columns are significantly different (P<.05).

137

138

VAUGHTERS ETAL.

TABLE 5. Effect of feeding schedule, starter diet protein concentration, and grower diet energy level on body •weight gains, feed consumption, and feed efficiency of breeder males at 19 weeks (Experiment l)1 Feeding schedule Grower diet

Starter diet

(kcal/g)

(% protein)

2.85

15 20 15 20

2.00

Full fed

Every day 138-day Weight

4.93 ± 4.82+ 3.51 + 3.35 + 4.15 a

Mean

.00 .03 .02 .00

2.53 + 2.51 + 2.15 ± 2.04 + 2.31b

4.30 ± 4.04 ± 2.89 ± 2.58 ± 3.45 a

.04 .04 .02 .01

15 20 15 20

19.48 ± 22.10 ± 20.05 ± 22.02 ± 20.91 a

.13 .54 .54 .62

Mean

Mean y 3

2.41 ± 2.32 + 1.96 ± 1.92 + 2.15 c

.04 .06 .03 .03

3.25 a

2.92 a 2.83 b

2.49 b

n

1.91 ± .00 1.74 ± .04 1.52 ± .05 1.26 ± .05 1.61 b

1.79 ± .05 1.55 ± .11 1.33 ± .06 1.17 ± .08 1.46c

2.56 a

2.29 a 2.06 b

1.79 b

138-day Consun 2.85 2.00 Mean

8.59 ± 12.07 ± 8.79 ± 12.00 ± 10.36 b

.01 .06 .31 .15

- to 138-day Eff 2.85

15 20 15 20

2.00 Mean

.220 ± .202 ± .131 ± .117 + .168 a

.003 .004 .004 .004

.222 ± .198 ± .126 ± .105 ± .163 a

.000 .011 .003 .005

8.57 ± 12.03 ± 8.54 ± 12.01 ± 10.28 b

.04 .13 .05 .04

iciency .209 ± .181 ± .111 ± .097 ± .150 b

.006 .014 .004 .006

15.37 a 12.33 b

.205 a .115 b

13.80 a 13.90 a

.170 a .150 b

' ' Values with different superscript within columns or within rows are significantly different (P<.05). 'Mean + SE. 2

Mean x = mean by grower diet.

3

Mean v = mean by starter diet.

starter (Table 11), but no differences were found in other organs. During the growing period males fed the 15% protein grower diet gained and weighed more than those fed 12% or 18% protein diets (Table 12), and those males fed 15% ED gained and weighed significantly more than those fed 20% EOD. Feed consumption was nearly identical under all treatments. Again, this was due to better feed efficiency by the 15% ED-fed birds (Table 13). Shank length was not affected by feeding schedule, but the 18% protein growing diet produced longer shanks (Table 13). Mortality was highest when males were fed 18% protein and lowest when males were fed 15% protein. Feeding schedule did not appear to affect mortality (P>.05).

Between-pen variability of body weights was greatest when males were fed 15% ED or 18% protein (Table 14). There were no differences in variability in shank lengths due to feeding schedule or grower diet protein concentration. Some organ weight differences were found at 20 weeks of age. The heart was larger and the intestine smaller in males fed on the 15% ED schedule (Table 15). A significantly smaller intestine was also present in those fed 15% protein. No differences occurred in the breast muscle due to feeding schedule, but there was a slight increase when birds were fed a 15% protein grower diet. The high protein diet produced a slight increase in pancreas weight. Gumboro titers were measured and the reciprocal end point dilutions where antibodies were detected were 675:1 for males raised on low

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2.00

15 20 15 20

Mean x 2

KKg)

.01 .07 .06 .08

r +-n 1 2 D r l . , , f

2.85

Every other day

FEEDING BROILER BREEDER MALES

139

TABLE 6. The effect of feeding schedule, starter diet protein concentration, and grower diet energy level on shank length and mortality of breeder males at 19 weeks (Experiment l)1 Feeding schedule Starter diet

Full fed

2.85

15 20 15 20

21.7 ± 22.0 ± 20.6 ± 20.6 ± 21.2 a

15 20 15 20

22 20 7 10

2.00 Mean 2.85 2.00

± ± ± ±

.4 .1 .1 .2

11 2 0 7

Every other day

Mean x 2

Meany 3

19.3 ± 19.3 ± 19.1 ± 19.2 ± 19.2 b

19.6 ± 19.6+ 18.5 ± 18.8 + 19.1 b

20.3 a

19.8 a 19.9 a

10 8 18 10

15a

Mean

Every day

.1 .2 .3 .1

±0 ±4 ±1 ±3

9 7 11 28

.1 .2 .1 .2

19.5 b

13a

±2 ±0 ±4 ±4

13a 14a

14a

14a

12a

a,b. Values with different superscripts within columns or within rows are significantly different (P<.05). Mean ± SE. Mean x = mean by grower diet. Mean„ = mean by starter diet.

TABLE 7. Coefficients of variation of body weight and shank length means of 19 week old breeder males fed two starter diet protein levels and two grower diet energy levels by different schedules (Experiment l)1 Feeding schedule Grower diet

Starter diet

(kcal/g)

(% Protein)

2.85 2.00

Every day

Full fed

Mean x 2

Meany 3

18.4 a

17.7 a 18.7 a

— Body weight (i[iS>

15 20 15 20

16.5 ± 14.4 ± 12.5 ± 14.5 ± 14.5 b

1.0 2.9 .7 .8

15 20 15 20

4.2 ± 5.7 ± 5.5 ± 5.7 ± 5.3 a

.4 .7 .2 .7

Mean

Every other day

18.8 ± 23.3 ± 19.7 ± 20.8 ± 19.5 a

1.7 .9 1.0 2.1

5.9 ± 5.6+ 6.9 ± 5.2 ± 5.9 a

1.4 .6 1.0 .3

18.3 ± 19.0 ± 20.2 ± 20.4 ± 20.6 a

1.0 1.0 1.1 .4

18.0 a

Shank length (( 2.85 2.00 Mean

4.2 ± 5.7 ± 7.0 ± 5.1 ± 5.5 a

.8 .4 .4 .3

5.2 a 5.9 a

5.6 a 5.5 a

a ' b Values with different superscripts within columns or within rows are significantly different (P<.05). 1

Mean ± SE.

2

Mean x = mean by grower diet.

3

Mean y = mean by starter diet.

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Grower diet

15 20

<.001

Gain

.001

Efficiency

Starting period

<.001

Shank length .043 -C001 .006 .453 .725 <.001

Gain

1

Mean + SE.

.014 .673 <.001 .764 .296 .724

Efficiency

Growing period

.582 <.001 .002 .399 .520 <.001

Weight

.515 ± .010 a .795 ± .012 b

Gain (kg)

1.150 ± .031 a 1.390+ . 0 2 1 b

Consumption

TABLE 9. Effect of starting diet protein concentration on gain feed consumption and feed e for breeder males at 4 weeks (Experiment 2)1

Based on arcsine-transformed data.

df

a ' b Values with different superscripts within columns are significantly different (P<.05).

(%)

df

2

Probability that differences observed occurred by chance.

Degrees of freedom.

Starter protein

3

2

1

Starting diet (SD) Growing diet (GD) Feeding schedule (FS) SDX FS SDX GD GDX FS

Independent variable

TABLE 8. Significance probabilities1 for the effects of starting diet protein level (15 vs. 20%), growing diet energy and feeding schedule (full fed vs. restricted every day vs. restricted every other day) on the growth and developm

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12.18±.08

13.01 ± 2 . 5 2 b

28.98 ± 3.29 a

Body weight CV

.785±.015b

.611±.019a

,644±.017

a

a

.020 ± .001 a

.018 ± .002

Testes

4.748 ± .106 b

4.014 ± . 0 9 1

a

Left pectoralis major

ab ' Values with different superscripts within columns are significantly different (P<.05). 1 Mean ± SE.

.611±.033

15

20

a

t\,z\

<%)

Heart

.„,>

3.875 ± .1

4.473 ± .2

Total intestine

TABLE 11. Effect of starting diet protein concentration on organ weights as a percent of body weight of bre

Mean ± SE.

' Values with different superscripts within columns are significantly different (P<.05).

Body weight

1

a

Starter protein

20

(cm) 10.91 ± .07 a

(%) 15 b

Shank length

Starter protein

TABLE 10. Effect of starting diet protein concentration on shank length and on coefficients of and shank length means of 4Jweek-old breeder males (Experiment 2)1

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142

VAUGHTERS ETAL. TABLE 12. Effects of feeding schedule, starting diet protein concentration, and growing diet protein concentration on final body weight, gain, and feed consumption for breeder males at 20 weeks (Experiment 2)1 Feeding schedule

Grower diet

Every day

Every other day

(% Protein)

(15% Starter diet)

(20% Starter diet)

12 15 18 Mean

2.08 ± .02 2.17 + .01 2.09 ± .03 2.11*

12 15 18 Mean

1.53 ± .01 1.61 ± .02 1.54 ± .05 1.56*

1.13 ± .01 1.22 ± .03 1.14 ± .02 1.16 b

1.33* 1.42 b 1.34*

12 15 18 Mean

7.96 ± .02 7.95 ± .01 8.01 ± .02 7.97*

7.98 ± .02 7.96 ± .02 8.02 ± .06 7.98*

7.97* 7.95* 8.01*

2.02* 2.11b 2.03*

ab ' Values with different superscripts within columns or within rows are significantly different (P<.05). 1

Mean ± SE.

TABLE 13. Effects of feeding schedule, starting diet protein concentration, and growing diet protein concentration on efficiency, shank length, and mortality of breeder males at 20 weeks (Experiment 2)1 Grower diet

Every day

Every other day

(% Protein)

(15% Starter diet)

(20% Starter diet)

.192 ± .001 .202 ± .002 .193 ± .006 .196*

.141 ± .001 .154 ± .005 .143 ± .002 .146 b

12 15 18 Mean

Mean

.167* .178 b .168*

12 15 18 Mean

19.91 ± .11 19.82 ± .14 19.55 ± .11 19.76*

19.79 ± .04 19.80 ± .12 19.44 ± .10 19.68*

19.85* 19.81* 19.50 b

12 15 18 Mean

20 12 30 20*

17 12 22 17*

l8ab 12* 26b

±6 ±4 ± 8

±2 +3 ±4

ab ' Values with different superscripts within columns or within rows are significantly different (P<.05). ' M e a n t SE.

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vveigiu, n u ways (.Kg; 1.97 ± .01 2.06 ± .03 1.97 + .01 2.00 b

Mean

FEEDING BROILER BREEDER MALES TABLE 14. Coefficients of variation of body weight and shank length means of20-week-old fed two starter diet protein levels and three grower diet protein levels by different schedules (Experiment 2)1

143 breeder males

Grower diet

Every day

Every other day

(% Protein)

(15% Starter diet)

(20% Starter diet)

12 15 18 Mean

20.15 ± 4.63 21.06 ± 2.40 24.04 ± 2.21 21.75 a

15.31 ± 1.31 15.97+ 1.09 20.23 ± 5.35

17.73 a 18.52 a 22.14 b

12 15 18 Mean

4.94 ± 1.57 4.59 ± .32 4.89 ± .85 4.81 a

3.95 ± .95 4.50 ± .49 4.55 ± .89 4.33 a

4.45 a 4.55 a 4.72 a

Mean

1

Mean + SE.

protein starter and 336:1 for those raised on high protein starter diets. Semen volume and PCV were not affected by feeding schedule or by grower diet (Table 16). Fertility was higher during the 4-week test period for those males grown on 18% protein and consistently lower for those that had received 15% protein. Males grown on 12% protein were intermediate in fertility. At 24, 25, and 27 weeks of age, fertility was higher for those birds fed 15% ED. The males fed 20% EOD had improved fertility during week 26. Differences were smaller (1%) but significant. DISCUSSION

The production of smaller chicks at 4 weeks of age by feeding the 15 vs. 20% protein diet (Tables 3,8, and 9) was expected from the literature (Waldroup and Harms, 1962; Waldroup et al., 1966; Jones et al., 1967). However, it was not expected that these smaller chicks would be larger at 20 weeks as a result of eating identical amounts of grower diet fed larger chicks (Tables 8, 12, and 13). It may be that small chicks used a reduced proportion of their feed for maintenance and thus had a larger proportion available for growth, or that their early low plane of nutrition conditioned them to use feed more efficiently, or both. Because there was more than 1 month's difference in hatch dates of the two flocks, tempera-

ture differences and day length differences probably contributed to the difference in feed consumption patterns between the experiments. Males in Experiment 2 were exposed to a longer day and warmer temperatures. Had the males fed 15% protein consumed and gained as much as in Experiment 1, variability in body weights and frame or skeletal size (as indicated by shank length) may have been reduced (Tables 4 and 10). Differences in variability in Experiment 2 were obvious upon visual inspection of the birds. This is indicative of Gumboro disease, for which the birds had not been vaccinated. Antibody titers measured at 20 weeks of age indicated that the chicks fed low protein had been exposed to Gumboro and suffered the disease to a greater extent than the chicks fed 20% protein. Thus, it is possible that a 15% protein starter diet is adequate under good management conditions, but not if the males are subjected to the stress of exposure to disease. The difference in pectoralis major weights in Experiment 2 parallels the difference in frame size (Tables 9 and 11). The larger size can be attributed to bone and muscle differences because organ measurements in Experiment 2 showed no differences due to starter diets. Every day feeding appears to be preferable to EOD feeding for body weights, gains, and feed efficiency. This was reported by Pesti (1984) for standard, and Leeson and Summers (1985) for dwarf broiler breeders (Tables 5, 12, and 13). Males fed ED were 7% heavier than males

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ab ' Values with different superscripts within columns or within rows are significantly different (P<.05).

VAUGHTERS ETAL.

144

TABLE 15. Effect of feeding schedule, starting diet protein concentration, and growing diet protein concentration on organ weights as a percent of body weight at 20 weeks (Experiment 2)1 Feeding schedule Grower diet

Every day

(% Protein)

(15% Starter diet)

Every other day

Mean

(20% Starter diet) - Heart

.341 ± .014 .361 ± .008 .329 ± .027 .343 a

.313 ± .008 .315 ± .006 .315 ± .024 .315 b

12 15 18 Mean

.017 + .001 .019 ± .001 .016 ± .001 .017 a

Testes .015 + .002 .017 ± .001 .018 ± .002 .017 a

12 15 18 Mean

4.690 ± .140 5.433 ± .161 4.972 ± .279 5.032 a

12 15 18 Mean

1.842 ± .154 1.268 + .027 1.529 ± .098 1.547 a

1.853 ± .090 1.599 ± .067 1.854 ± .123 1.769 b

12 15 18 Mean

1.313 ± .052 1.362 ± .033 1.418* .160 1.364 a

1.302 ± .008 1.373 ± .065 1.357 ± .019 1.344 a

12 15 18 Mean

.175 ± .018 .171 ± .007 .187 ± .006 .178 a

.327a .338a .322a

.016a .018a .017a

- Left pectoralis major • 4.515 ± .147 4.824 ± .119 4.947 ± .156 4.762 a

4.603a 5.128b 4.960ab

Total intestine • 1.848a 1.434b 1.692a

Liver ——— 1.308a 1.368a 1.387a

— Pancreas .169 ± .005 .187 ± .014 .213 + .005 .190 a

.172a .179:ab .200b

ab ' Values with different superscripts within columns and within rows are significantly different (P<.05). ' M e a n t SE.

fed EOD in Experiment 1 and 5% heavier in Experiment 2. These gains resulted without changes in frame size (shank length), mortality, or variabilities (Tables 6, 7, 13, and 14). The ED technique promises substantial feed savings if it can be adopted by the commercial industry without complications. In both experiments variability in body weight was similar at 4, 19, and 20 weeks (Tables 4, 7, 10, and 14). High variability at 4 weeks resulted in high variability at 20 weeks. These results indicate that variability at 19 or 20 weeks is closely related to variability at 4 weeks, and is not affected differently by ED or

EOD feeding during the grow out period. Producers should be concerned about flock uniformity when birds are placed in the breeder house. Further investigation is needed in methods to overcome variability once it has occurred. Low energy grower diets appeared to be acceptable although body weights, gains, and efficiencies at 19 weeks were reduced by use of 2.00 kcal/g diets (Table 5). Fifteen percent protein grower diets also appeared to be preferable to other levels because body weights, gains, and efficiencies were significantly improved by their use (Tables 12 and 13). Quantities to feed are really questions of economics. If low energy

Downloaded from http://ps.oxfordjournals.org/ at Cornell University Library on June 26, 2015

12 15 18 Mean

27

26

.06 .07 .11

.04 .09 .06

.05 .06 .06

.41* .48* .44*

.43* .45* .40*

.38* .40* .44*

.34* .24* .29*

Mean

9.46 ± 7.83 ± 11.20 + 9.36* 14.22 + 13.87 ± 14.64 ± 14.25* 13.89 ± 16.58 ± 11.81 ± 14.17* 15.38 ± 18.04 ± 16.09 ± 16.52* 2.27 1.82 2.08

1.31 1.28 1.49

1.58 1.11 1.42

1.46 1.60 2.55

10.39 ± 7.68 + 9.37 ± 9.10* 14.31 ± 14.20 + 15.50 ± 14.70* 13.51 ± 13.12 ± 15.05 ± 13.91* 17.78 ± 17.98 ± 20.12 ± 18.71* 2.69 1.02 1.55

1.92 1.67 1.27

.86

1.14

.67

.90 .95

1.12

(20% Starter)

Every oither day

Packed cell volume

(15% Starter)

Every day

'Mean + SE.

' ' Values with different superscripts within columns and within rows are significantly different (P<.05).

18 Mean

12 15

Mean

12 15 18

Mean

12 15 18

Mean

.38 ± .10 .25 + .04 .34 + .04 .32* .38 ± .05 .35 ± .03 .53 ± .07 .42* .41 + .06 .38 ± .05 .45 ± .08 .41* .41 ± .09 .41 ± .04 .45 ± .08 .42*

25

(20% Starter)

.31 ± .21 ± .23 ± .26* .39 ± .44 ± .34 ± .39* .45 ± .54 ± .34 ± .45* .41 ± .55 ± .44 ± .47*

12 15 18

.06 .03 .04

(15% Starter)

(% Protein)

(Weeks)

24

Every other day

Every day

Growing diet

Age

Semen volume

16.45 18.01 18.21

13.71 14.85 13.52

14.27 14.03 15.07

9.93 7.75 10.17

Mean

TABLE 16. Effect of feeding schedule, starting diet protein concentration, growing diet protein concen semen packed cell volume, and fertility at sexual maturity in broiler breeder males (E

from http://ps.oxfordjournals.org/ at Cornell University Library on June 26, 2015

146

VAUGHTERS ET AL.

if the results reported here can be confirmed with birds kept under commercial conditions. ACKNOWLEDGMENT

This research was supported by state and Hatch funds allocated to the Georgia Agricultural Experiment Stations of the University of Georgia. The authors gratefully acknowledge the able technical assistance of Lynn O. Faust. REFERENCES Anonymous, 1965. Skip-a-day pullet feeding. Poult. Dig. 24:325-327. Arscott, G. H., and R. V. Kuhns, 1969. Packed sperm volume versus optical density as a measure of semen concentration. Poultry Sci. 48:1126-1127. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Harms, R. H., B. L. Damron, and H. R. Wilson, 1968. Performance of broiler breeder pullets as influenced by composition of grower and layer diets. Br. Poult. Sci. 9:359-366. Hubbard Management Guide, 1983. Hubbard Farms, Walpole, NH. Jones, J. E., H. R. Wilson, R. H. Harms, C. F. Simpson, and P. W. Waldroup, 1967. Reproductive performance in male chickens fed protein deficient diets during the rearing period. Poultry Sci. 46:1569-1577. Leeson, S., and J. D. Summers, 1985. Effect of cage versus floor rearing and skip-a-day versus every-day feed restriction on performance of dwarf broiler breeders and their offspring. Poultry Sci. 64:1742-1749. Luckham, D. G., S. J. Slinger, I. R. Slinger, I. R. Sibbald, and G. C. Ashton, 1963. Methods of restricting feed or energy intake of growing Leghorn pullets and their effect on subsequent reproductive performance. Poultry Sci. 42:1285. (Abstr.) National Research Council, 1984. Nutrient Requirement of Domestic Animals. 1. Nutrient Requirements of Poultry. Natl. Acad. Sci., Washington, DC. Pesti, G. M., 1984. Proc. 1984 World Poultry Sci. Assoc. Mtg., Helsinki, Finland. SAS User's Guide, 1979. SAS Inst., 1979. 9th ed. Raleigh, N.C. Waldroup, P. W, B. L. Damron, and R. H. Harms, 1966. The effect of low protein and high fiber grower diets on the performance of broiler pullets. Poultry Sci. 45:393-401. Waldroup, P. W, and R. H. Harms, 1962. Effect of grower diets on the performance of egg production type pullets. Fla. Agric. Exp. St. Tech. Bull. 646. Wilson, H. R., L. O. Rowland, Jr., andR. H. Harms, 1971. Use of low protein grower diets to delay sexual maturity of broiler breeding males. Br. Poult. Sci. 12:157-163. Wilson, H. R., R. A. Voitle, and R. H. Harms, 1972. Reproductive capacity of broiler males following protein restriction at various ages. Nutr. Rep. Int. 5:9-15. Wilson, H. R., P. W. Waldroup, J. E. Jones, D. J. Duerre, and R. H. Harms, 1965. Protein levels in growing diets and reproductive performance of cockerels. J. Nutr. 85:29-37.

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and low protein diets are inexpensive enough, they could be used to produce capable males. However, more feed would be required to maintain performance, so both prices and performance need to be compared. Testes weight results did not agree with previous results with White Leghorn males (Table 16). Wilson et al. (1965) and Jones et al. (1967) reported smaller testes weights just prior to sexual maturity in males fed low protein diets (< 10%); results from the present experiment indicate no difference due to protein level. Results of experiments by Wilson et al. (1971) with broiler breeder males and Wilson et al. (1972) are similar to the present experiment wherein semen volume and semen concentrations were not affected by low protein grower diets. Only fertility gave an indication of the effects of feeding schedule or grower diets. In 3 of the 4 weeks studied fertility was better in birds fed ED, but the difference was only about 1%. This was not surprising because males were heavier, and heavier males generally mature first. Use of the 18% protein grower diet produced consistently higher fertility throughout the test period. The 12% protein diet gave fertility that was intermediate, and males fed 15% protein consistently had the lowest fertility. Wilson etal. (1971, 1972) found better fertility when low protein grower diets were fed, and those results are confirmed by those reported here: the 12% protein grower diet produced better fertility than did the 15% protein grower diet. The EOD feeding schedule was adopted by the poultry industry without critical comparisons with ED schedules. In early studies with pullets fed EOD (on range), it was a method of producing quantitative restriction and a qualitative change to feeding on more growing vegetation. The present studies and those of Leeson and Summers (1985) indicate that the EOD practice results in feeding wastage when adapted to modern confinement conditions. Feed savings resulted from ED feeding without an increase in bird variation. Additional benefits of ED feeding are a reduction in litter consumption (decreasing exposure to disease and parasites) and less aggressive breeders (our observation with these two flocks and one other; Pesti, 1984). Fifteen percent protein starter diets followed by ED feeding appears to be a viable alternative to the present system of higher protein and EOD feeding