The effects of forced molting nutritional methods on semi-heavy layer performance during such period

Introduction

Molting is characterized by a period of time in which hens experience a reduced or even halted egg production, aiming to renew their feathers and restore their reproductive tracts. This phenomenon typically occurs during decreasing photoperiod times (winter), and it can last for nearly 4 months (Silva, 2000). Nevertheless, this does not assure that birds will continue laying eggs during a second cycle.

The technique of forcing layers to molt in an attempt to optimize egg production for one additional cycle, was first used in the US in the 1960s, but currently several other methods are being evaluated. In the practice, the most popular methods include several different management practices. The feed restriction method is most popular due to its low cost and high efficiency (Rodrigues et al., 1995). In Brazil, the long-fasting technique (i.e., California method) is commonly used, but it has been questioned lately since it badly affects animal welfare. This is why the search is ongoing for alternative methods in agreement with both market perspectives and farm convenience.

In accordance with Lee (1982), when forced molting is practiced properly, it results in increased laying rates and improved internal/external egg quality during the second cycle, as compared with the late stages of the first laying cycle.

Among the major consequences of molting, despite of the use of alternative methods, body weight losses occur thus interfering with the late stages of the first laying cycle. In addition, high mortality rates occur.

The objective of this research was to study the effects of applying various forced molting methods on the productive performance of commercial layers.

Materials and Methods

The study was carried out in the experimental farm, Visconde de Graça Agritechnical Cluster (CAVG/UFPel), Brazil. Four hundred and forty eight (448) 100-week-old Hisex Brown hens were divided into two 32-cage batteries within a blackout house. The lighting program included 8 hours of light per day.

The experimental design was completely at random, and the experimental unit was one 7-bird cage. Each treatment included 16 repetitions. The experimental period lasted for 14 days.

Birds were subjected to 4 treatments: T1, 10-day fasting (control group) plus 4 days with ground corn; T2, soy hulls + vitamin premix; T3, wheat bran + vitamin premix; T4, high tannin sorghum + vitamin premix. In the fed groups, feed was given daily at the rate of 100 g per bird. Water was given ad libitum. In T2, T3 and T4 the feeds were offered for 14 days on a row.

The variables evaluated in this period included feed intake (FI) recorded daily, live weight (LW), weight loss (WL) in the 10-day period, egg (ED), livability (LIV) and mortality (MORT).

Data was subjected to both analysis of variance (ANOVA) and Tukey´s test (P<0.05).

Results and Discussion

Results are shown in Table 1.

Table 1. Comparison of different forced molting methods regarding layer performance

	FI (g)	LW (g)	WL(g)	LIV (%)	ED(%)	MORT(%)
T1	0.00^c	1,328.19^b	526.88^a	88.39^a	3.63^b	2.06^b
T2	3,425.38^b	1,447.88^b	399.38^b	91.96^a	3.94^b	2.06^b
T3	6,484.94^a	1,719.75^a	132.38^c	95.53^a	5.69^b	3.13^b
T4	675.94^a	1,729.31^a	131.13^c	97.32^a	10.38^a	5.38^a
P²	<0.0001	<0.0001	<0.0001	0.0877	<0.0001	<0.0001
CV	11.35	9.40	-26.07	11.23	61.35	57.17
Standard error	464.98	146.29	77.53	10.47	3.62	1.80

^{Means with different letters are statistically different (P<0.05).}

Significant differences were found in the following variables: FI, LW, ED, and MORT.

Regarding FI and WL, no statistical differences were found between T3 and T4. Also no statistical differences were found in LW between T1 and T2, or between T3 and T4.

T2 differed from all other treatments in terms of FI, while T1 had significant differences with all other treatments regarding FI. This is due to the fact that birds were subjected to feed restriction, leading to increased WL. T2 resulted in a lower FI reduction. In T3 and T4, WL can be explained by the fact that the diet included fibrous, low palatable ingredients thus reducing digestibility.

T4 caused lower MORT and increased lay persistence due to higher FI, which means a lower efficacy to halt egg production thus delaying the start of a new cycle. This means that feed restriction time needs to be extended.

In accordance with Schmidt and Figueiredo (2004), the selection of birds for the second laying cycle is one factor impacting egg production/quality/quantity in the second cycle, so that WL control becomes crucial at molting, as shown in T4.

No statistical differences were detected in any of the treatments regarding flock LIV, which ensures that forced molting is one of the best ways for hens to continue laying eggs.

Conclusions

The forced molting methods applied herein showed to be suitable to replace the conventional fasting method, since they resulted in good livability and small variations. Forced molting by the use of a high-tannin sorghum diet shows advantages in terms of mortality, even though it does not increase egg production significantly, and results in a slower molting process. The use of soy hulls was a more efficient as an alternative to stop egg production within a short time period.

Bibliography

Lee K. 1982. Effects of forced molt period on posmolt performance of leghorn hens. Poultry Science 61(10):1594-1598.

Rodrigues PB, Bertechini AG, Oliveira BL. 1995. Fatores nutricionais que influenciam o desempenho e a qualidade do ovo de poedeiras comerciais no segundo ciclo de produção. p. 478-479. In: Reunião Da Sociedade Brasileira De Zootecnia. 1992. Brasília. Anais... Brasília: Sociedade Brasileira de Zootecnia.

Schmidt GS & Figueiredo EAP. 2004. Efeito da seleção no primeiro ciclo de postura para produção de ovos sobre o desempenho no segundo ciclo. Ciência Rural 34(1) jan./fev.

Silva JA. 2000. Muda forçada! Como? Quando? Porque?. Revista Alimentação Animal 17:7-8, - jan./mar. Disponível em http:// www.portalaveworld.com.br. Acesso em 28/06/2009.

The effects of forced molting nutritional methods on semi-heavy layer performance during such period

Evonik Animal Nutrition

Hangzhou DE Mark Industrial Co Ltd

Hy-Line International

Life Rainbow