Broiler Breeder Nutrition and Feed Management Affects Broiler Progeny Performance

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Categoria: 47esimo CN2010

John T. Brake, Ph.D., PAS
William Neal Reynolds Distinguished Professor  of Poultry Science, Physiology, and Nutrition
Department of Poultry Science, NC State University, Raleigh, NC 27695-7608 USA

Abstract: A series of experiments were conducted to test the hypothesis that the feeding management applied to broiler parent stock (broiler breeders) could alter the performance of the broiler progeny. The broiler breeders were reared in typical litter floor black-out facilities and were moved to slat-litter breeder facilities and photostimulated at 21-22 weeks of age.

In Experiment 1 broiler breeder males were reared on two different cumulative feeding programs providing either 29,580 kcal of ME and 1,470 g of CP or 33,500 kcal of ME and 1,730 g of CP to produce either a Low body weight (Low BW) or High body weight (High BW) at 21 weeks of age, respectively. From 21 weeks of age the males were fed a common diet in the same daily quantity irrespective of the fact that there was a difference in body weight at 21 weeks of age. These males were weighed individually on a regular basis to monitor this effect. Broiler chicks were hatched from eggs collected at 29 weeks of age and grown to 42 days of age. The Low BW males exhibited numerically better fertility (P<0.10) and improved broiler body weight (P<0.06) at 29 weeks of age. As might be expected, the transition to the same feed allocation during the breeding period caused a transient plateau in body weight gain from 22 to 32 weeks of age for the High BW males. Examination of the individual body weight data revealed that it was only the largest males in the High BW treatment that experienced this failure to consistently gain body weight. Thus, the larger males with the superior genetic potential evidently did not mate and produce progeny.

In Experiment 2, two male feeding programs were applied during the production period (Constant or Increasing) beginning at 26 weeks of age. Broilers were hatched at 50 week of age and grown to 42 days of age to evaluate the effect of male treatments on progeny performance. The Constant program elicited lower broiler breeder fertility from 36 to 55 wk of age and this resulted in a lower broiler progeny BW and poorer adjusted feed conversion at 42 d of age. In this case, the larger males in the Increase treatment exhibited a consistent body weight increase while the larger males in the Constant treatment did not. Increasing male feed allocation during the production period improved fertility and favorably impacted progeny performance because the larger males continued to mate.

To evaluate the vertical effects of cumulative nutrition during broiler breeder pullet rearing on performance of broiler offspring, broiler chicks were hatched from broiler breeder females reared on a range of cumulative nutrition in three trials that used graded levels of cumulative crude protein (CP) and metabolizable energy (ME) intakes (High (27,788 kcal ME and 1,485 g CP), Medium (26,020 kcal ME and 1,391 g CP), Low (24,242 kcal ME and 1,296 g CP)) to 22 weeks of age. Breeder reproductive performance was not significantly affected. The high plane of cumulative breeder pullet nutrition increased 21-day broiler male BW in Broiler Trials 1 (P<0.05), 2 (P<0.06), and 4 (P<0.08) at 27, 28, and 33 weeks of age, respectively. There was no significant effect in Broiler Trial 3 when the breeders were 39 weeks of age. Greater broiler breeder pullet nutrition during rearing appeared to positively affect subsequent male broiler growth from early lay broiler breeders without significant impact on breeder performance.

Introduction

Although quantitative feed restriction of broiler parent stock (broiler breeders) has long been known to be required to prevent the most obvious effect of the continued improvement in broiler genetics, excess body weight, it has not been as apparent that this obligatory management might also alter broiler progeny performance in a negative manner. It has become clear that improvements in broiler feed conversion are reducing the amount of feed required to rear a broiler breeder to a given body weight, but selection for growth rate, feed efficiency, and conformation on relatively high density diets has apparently not decreased the nutrient requirements for proper sexual development in a proportionate manner (Walsh, 1996). In fact, it is tempting to suggest that many reproductive problems have been simply due to insufficient nutrition given the genetic and nutritional background of the primary breeding stock (Siegel and Dunnington, 1985). This was also suggested by the work of Sorneson (1980; 1985) who selected meat‑type chickens for increased growth rate on high and low protein diets. When tested on the low protein diet, the low protein selected line progeny grew substantially faster than the high protein line progeny. This meant that the plane of nutrition at the parent stock level would influence the required plane of nutrition at the progeny level. The implications of the protein component of this process on parent stock were further delineated by the work of Lilburn et al. (1992) who reared a heavy weight quail line, selected for several generations on a 28% CP diet, to sexual maturity on a standard 24% CP diet known to produce sexual maturity at 42 days of age in a random bred control line.  Sexual maturity was delayed in the heavy weight line when fed the 24% CP diet (a diet that was suggested by the NRC to be adequate) but the delay in sexual maturity was significantly decreased by rearing the heavy weight line birds on a 30% CP diet, which was more similar to the selection diet. It must be remembered that one of the first problems that arose in modern broiler breeders was delayed onset of sexual maturity. Subsequently, our laboratory demonstrated a specific cumulative protein need for rearing pullets, irrespective of body weight, that seriously called into question the paradigmal view of a need for absolute control of body weight relative to published reference standards provided by primary breeding companies (Walsh and Brake, 1997, 1999). Thus, it must be recognized that broiler parent stock (broiler breeders) females and males continue to exhibit similar improved conformation, growth rate, and feed conversion. This has created broiler breeders that can easily reach their standard (target) body weights during rearing even though they were grown without sufficient nutrition to reproduce and live optimally through the entire production cycle. Many long-standing paradigms need to be reconsidered.

The results of the broiler progeny have long been recognized as being as important as fertility and egg production as outcomes of good broiler breeder management but data to clearly relate broiler breeder management to broiler performance have been scarce. Less than optimum broiler performance has been observed frequently during the early and late stages of production by commercial broiler breeder flocks. Therefore, it was deemed important to investigate how the management of broiler breeder males and females could affect the performance of the broiler progeny produced by broiler breeder flocks during the early and late stages of production.

Feeding Management of Broiler Breeder Males

In order to study how the feeding management of broiler breeder males could affect broiler progeny a series of studies were undertaken. Broiler breeders were reared sex-separate in a typical black-out house to 21 weeks of age in the presence of 23 hours of light for 7 days followed by 8 hours of light daily. Birds were moved at 21 weeks of age to a curtain-sided, two-thirds slat and litter house where the photoperiod was extended with artificial light to 14 h and 15 h at 21 and 23 weeks of age, and to 15.5 and 16 h at 5% and 50% rate of lay, respectively. All broiler breeder females received a starter diet from 0 to 2 weeks followed by a grower diet to 24 weeks and a breeder diet thereafter. The separate-reared males were managed such that very similar body weight distributions were present in each replicate pen when selected and mixed with replicate pens of females at 21 weeks of age. This was to insure that the normal range of male body weights (therefore similar range of genetic potential) was fairly represented within each replicate breeding pen, and therefore, within each treatment.

In Experiment 1 broiler breeder males were reared on two different cumulative feeding programs providing either 29,580 kcal of ME and 1,470 g of CP or 33,500 kcal of ME and 1,730 g of CP to produce either a Low or High body weight (BW) at 21 weeks of age, respectively (Romero-Sanchez et al., 2007b). From 21 weeks of age the males were fed a common diet in the same daily quantity irrespective of the fact that there was a difference in body weight at 21 weeks of age. This intentionally underfed some larger males and males were weighed individually on a regular basis to monitor this effect. Broiler chicks were hatched from eggs collected at 29 weeks of age. There were 15 male chicks allocated to each pen in a 32-pen house with 16 replicate pens per breeder feeding treatment.

In Experiment 2 broiler breeder males were managed as described by Romero-Sanchez et al. (2007a). A cumulative intake of 31,460 kcal of ME and 1,669 g of CP was attained at 21 weeks of age for all males. Subsequently, two different feed allocation programs (Constant or Increase) were applied after 26 weeks of age (Romero-Sanchez et al., 2007c). The Constant feeding program maintained 110 g/male/d throughout the production period while the Increase feeding program provided biweekly increments of 1 g from 26 to 42 weeks and a similar increase every 4 weeks from 42 to 62 weeks until a daily feed intake of 123 g/male/d was reached. Broiler chicks were hatched from eggs collected at 48 weeks of age. There were 18 replicate pens of either 15 male or female chicks from each breeder feeding treatment within a 72-pen house.

The effect of male broiler breeder feeding program at 29 and 48 weeks of age on fertility and broiler progeny performance in Experiments 1 and 2, respectively, is shown in Table 1. In Experiment 1 the Low BW males exhibited numerically better fertility (P<0.10) and improved broiler body weight (P<0.06) at 29 weeks of age. There had been differences in broiler breeder male body weight during rearing but these differences diminished as the males began to be provided the same daily feed allocation, as would be expected. However, the transition to the same feed allocation during the breeding period did cause a transient plateau in body weight from 22 to 32 weeks of age for the High body weight males. Examination of the individual body weight data taken during this period of time revealed that it was only the largest males in the High body weight treatment that experienced this failure to consistently gain body weight. Fertility has been found to be largely a function of the number of males mating in a flock. In the case of the High body weight treatment the larger males were most likely not mating, as evidenced by a failure to gain body weight, and this resulted in lower broiler body weight. The logic for this explanation lies in the simple fact that the larger males in each treatment were most probably genetically similar so that when the largest males in the respective treatments did not mate the largest broilers were not produced. The larger males in the Low body weight treatment did not exhibit this effect as the daily allocation of ME was evidently sufficient to support normal growth and mating activity. This was most likely due to less than adequate ME to support their higher body weight. The smaller males in both treatments exhibited consistent body weight gain and presumably were equally efficient at mating.

Table 1.           Effect of male broiler breeder body weight (BW) and feeding program on fertility and broiler performance (adapted from Romero-Sanchez et al. 2008).

 

Experiment

Breeder

Flock Age

Breeder

Treatment

Fertility

Broiler

BW@42 days

Sex

 

(week)

(%)

(g)

1

29

Low BW1

97.6x

2766x

Male

 

 

High BW

96.2y

2669y

Male

 

 

 

 

 

 

2

48

Constant2

92.9b

2546b

Mix

 

 

Increase

95.2a

2604a

Mix

x,y  Means in a column within an experiment with no common superscripts differ at P < 0.10.
a,b  Means in a column within an experiment with no common superscripts differ at P < 0.05.
1 Low BW males were 3096 g and High BW males were 3,565 g at 21 weeks of age but were  fed in a similar manner thereafter in Experiment 1.
2 The Constant treatment males received 110 g of feed daily from 26 to 50 weeks of age while the Increase treatment males experienced an increase from 110 to 121 during the same period in Experiment 2.

The Increase feeding program during the production period produced improved broiler breeder fertility and greater broiler body weight at 48 weeks of age in Experiment 2 (Table 1). In Experiment 2 the body weight gain of the Increase treatment was greater than for the Constant treatment. Again, examination of the body weight data from individual males revealed that it was only the larger males that were the most affected by the apparently less than adequate feed (ME) allocation of the Constant versus Increase feeding programs. The failure to gain body weight in a consistent and appropriate manner was most likely the cause of the lower fertility of the Constant treatment as the larger males did not mate, as evidenced by lower broiler body weight. The data of Experiment 2 were similar to the reports of Attia et al. (1993; 1995) that showed improved broiler performance due to a greater daily ME allocation in Ross 344 broiler breeder males. {mosimage}

The conclusion appears to be simple. The broiler breeder males that produced the progeny with the greatest genetic potential were the largest broiler breeder males and they had to be fed in a programmed manner that achieved early sexual maturity and persistent fertility. Further, if fertility decreased due to less than adequate male ME allocation then there was a decrease in broiler body weight. This clearly demonstrated that the larger males in the broiler breeder flock produced the larger broilers and that they have to be fed appropriately in order to obtain maximum broiler performance.

Feeding Management of Broiler Breeder Females

To evaluate vertical effects of cumulative nutrition during the pullet rearing period on performance of broiler progeny, four broiler trials were conducted using chicks hatched from broiler breeder females reared on a range of cumulative nutrition in three consecutive broiler breeder trials. Breeder Trials 1 and 2 each used three graded levels of cumulative crude protein (CP and metabolizable energy (ME) intakes (High (27,788 kcal ME and 1,485 g CP), Medium (26,020 kcal ME and 1,391 g CP), and Low (24,242 kcal ME and 1,296 g CP)) for pullets to 22 weeks of age. Breeder Trial 3 used only the High and Low levels. The Low feeding program could be described as concave from 2 to 22 weeks of age while the High feeding program could be described as convex in form. The Medium program was linear and fell between the Low and High programs. Males were grown sex-separate on a 17% CP, 2.90 kcal/g ME growing diet to a cumulative nutrient intake of about 32,000 kcal ME and 1,600 grams CP as determined by our laboratory to be satisfactory (Peak, 1996; 2001). A single 16% CP, 2.90 kcal/g ME breeder laying diet and identical management practices were applied to breeder hens in all three breeder trials during the laying period. Males and females were fed separately the same breeder laying diet during the laying period. There were four replicate pens for each cumulative pullet nutrition treatment. The breeder facility was a two-thirds slat design with curtains and fans for ventilation. Breeders were moved from a black-out rearing (8 hours of light) facility to the laying facility and photostimulated (14 hours of light) at 22 weeks of age. Identity of breeder treatments was preserved during egg collection, egg storage, egg incubation, and chick processing. Broiler Trial 1 used chicks hatched from Breeder Trial 1 at 27 weeks of age. Broiler Trials 2 and 3 evaluated chicks hatched from Breeder Trial 2 at 28 and 39 weeks of age, respectively, and Broiler Trial 4 used chicks hatched from Breeder Trial 3 at 33 weeks of age. There were 12 pens of male and 12 pens of female broiler chicks from each breeder pullet cumulative nutrition treatment in Broiler Trials 1, 2, and 3 while there were 18 pens per sex in Broiler Trial 4.

There was no consistent effect of cumulative pullet nutrition on any reproductive variable measured. Egg production, fertility, and fertile hatchability were very similar and quite acceptable while percentage shell was not significantly affected. Egg weight (Table 2) was not significantly affected except at 34 weeks of age in Breeder Trial 3 where the High treatment exhibited greater egg weight.

 

TABLE 2. Effect of cumulative pullet nutrition during the rearing period on subsequent egg weight

 

Breeder Trial

 

Breeder Age

 

Cumulative Pullet Nutrition1

 

 

 

High

Medium

Low

 

 

(weeks)

---------------- (g) ----------------

 

1

28

57.2

56.4

56.4

 

1

34

63.9

62.9

63.9

 

1

46

68.3

68.2

68.4

 

2

28

55.3

57.2

54.5

 

2

34

63.8

63.2

62.7

 

2

40

67.4

67.0

66.7

 

3

28

58.6

-

57.4

 

3

34

64.8a

-

63.7b

 

3

40

66.6

 

66.2

 

a,b  Means in a column within a trial with no common superscripts differ at P < 0.05.

1Breeder Trials 1 and 2 each used three graded levels of cumulative crude protein (CP) and metabolizable energy (ME) intakes (High (27,788 kcal ME and 1,485 g CP), Medium (26,020 kcal ME and 1,391 g CP), Low (24,242 kcal ME and 1,296 g CP)) to 22 weeks of age. Breeder Trial 3 used only the High and Low levels.

 

All pullets were weighed at 22 weeks of age to confirm treatment effects and the Low, Medium, and High treatments typically weighed 2,450 grams, 2,550 grams, and 2,660 grams, respectively. Although pullet body weight did differ during rearing, these differences gradually disappeared during the laying period, as would be expected once a similar daily allocation of ME was applied. Body weights taken from 20 hens per pen near the time of each egg collection for each Broiler Trial are shown in Table 3.

 

TABLE 3. Effect of cumulative pullet nutrition during the rearing period on subsequent breeder hen body weight1

 

Broiler Trial

 

Breeder Trial

 

Breeder Age

 

Cumulative Pullet Nutrition

 

 

 

High

Medium

Low

 

 

(weeks)

----------------- (kg) --------------

1

1

26

3.2

3.3

3.3

2

2

28

3.6

3.6

3.5

3

2

40

4.0

4.0

3.9

4

3

32

3.8

-

3.8

1Hen body weights taken from a random sample of 20 hens from each of twelve 200-hen pens at the ages shown.

 

 

There were no consistent significant effects of plane of pullet cumulative nutrition on broiler feed conversion or mortality to 21 days of age (data not shown). However, there were reasonably consistent effects on broiler body weight as shown in Table 4. The high plane of cumulative breeder nutrition increased 21 day broiler male BW in Broiler Trials 1, 2, and 4. There was no effect in Broiler Trial 3 when the breeders were 39 weeks of age, as might be expected of a so-called “prime” flock, although there was a residual numerical effect. Female BW was affected by plane of breeder nutrition in Broiler Trial 2 only as the effect appeared to be less consistent for female offspring.

 

TABLE 4. Effect of cumulative pullet nutrition during the rearing period on subsequent 21-day broiler body weights

 

Broiler Trial

 

Breeder Trial

 

Breeder Age

 

Broiler Sex

 

Cumulative Pullet Nutrition1

 

P =

 

 

 

 

High

Medium

Low

 

 

 

(weeks)

 

-------------- (g) ---------------

 

1

1

27

M

910

850

900

0.01

1

1

27

F

810

810

800

0.93

2

2

28

M

950

940

900

0.06

2

2

28

F

900

870

860

0.03

3

2

39

M

950

920

920

0.31

3

2

39

F

870

890

870

0.57

4

3

33

M

920

-

890

0.09

4

3

33

F

830

-

860

0.28

1Breeder Trials 1 and 2 each used three graded levels of cumulative crude protein (CP) and metabolizable energy (ME) intakes (High (27,778 kcal ME and 1,485 g CP), Medium (26,020 kcal ME and 1,391 g CP), Low (24,242 kcal ME and 1,296 g CP)) to 21 weeks of age. Breeder Trial 3 used only the High and Low levels.

 

It was interesting to note that the male body weights at 21 days of age were in the 900 gram range. This was very good early broiler growth by most standards and the fact that the increased body weight observed in the male was evidenced in the presence of such good control (Low) performance was remarkable.

Conclusion

It is not unreasonable to assume that birds with greater genetic potential may need more nutrition in order to fully express their phenotype as the animals with greater genetic potential in this case would be expected to have a higher maintenance requirement and possibly a higher critical body weight to initiate and maintain reproduction, as suggested by these studies.

 

Many long held ideas about broiler breeder management apparently require thoughtful reconsideration. Nothing should be “sacred” when an analysis from a different perspective might well provide an explanation. Just because one has always done something in one manner does not mean that it necessarily has to continue to be done in that manner. One has to remember to “listen to the chickens!”