Livestock Research for Rural Development 14 (2) 2002

http://www.cipav.org.co/lrrd/lrrd14/2/faro142.htm

Egg production performance of commercial laying hens in Chakwal district, Pakistan

M Farooq, M A Mian, F R Durrani and M Syed 

Faculty of Animal Husbandry and veterinary sciences, NWFP,
Agricultural University, Peshawar, Pakistan.
geanes@psh.paknet.com.pk and durraniff@yahoo.com

 

Abstract

Data were collected during the years 2000-2001 in Chakwal district; Pakistan to investigate egg production performance of 109 randomly selected flocks.

Average age at point-of-lay, and at peak-of-lay, egg laying period, percent hen-day, and peak production and hen-day, and hen-housed egg production were 126±1.02 days, 200±4.84days, 241±4.84 days, 69.3±0.51%, 92.1±0.34%, 205.±3.61 eggs and 185.±3.60 eggs, respectively. Number of culled eggs per bird was 7.70±0.01, including 1.03±0.01% thin shell and 2.71±0.02%, broken eggs. Age at point-of-lay (b=1.130; p<0.0009) and peak-of-lay (b=0.145; p<0.03) had a positive association with mortality. Percent hen-day egg production was negatively associated with age at point-of-lay (b=-0.11; p<0.02) and mortality (b=‑0.32; p<0.014). Hen-day egg production was negatively associated with age at point-of-lay (b=‑0.40; p<0.08), mortality (b=‑1.26; p<0.028) and positively associated with percent hen-day egg production (b=1.45; p<0.001).

Better egg production was found for; Hisex strain of layer than Babcock, Nick-chick and Hyline;  for large than small sized flocks; for layers kept in cages than on floors; for flocks maintained at optimal stocking density under better hygiene as compared to flocks maintained at a higher stocking rate under poor hygiene.

Key words: Age at point-of- lay, cage vs. floor, egg production, housing, laying period, peak lay, stocking rate

Introduction

Eggs are the major business outputs in commercial table egg production and the higher the egg production the better will be the profit. Farooq et al (2001) found positive association of egg production with net profit in broiler breeders and reported major contribution of eggs in total returns. Verma and Singh (1997) reported 87.3% contribution of eggs to total returns.  Commercial egg type layers started laying eggs at the age of 20-21 weeks and produced 277 eggs till 72^nd week of their production cycle according to Petek (1999). North (1984) found 266 and 257 number of eggs as hen-day, and hen-housed egg production during 52 weeks laying period for layers kept in cages.

Egg production is a dependent variable and is influenced by several factors like strain of chicken, feeding, mortality, culling, health and management practices, age at point-of-lay, and peak lay and persistency of lay. North (1984), Petek (1999) and Tolimir and Masic (2000) observed variable egg production performance for various strains of chicken. Adams and Craig (1985) reported a decrease in egg production with increased stocking rate. Carey et al (1995) observed higher incidence of cracked eggs in over-crowded houses as compared to optimal stocking rate. Akyildiz et al (1993), Tanaka (1993) and Kristensen and Silleb-Kristensen (1996) reported that flocks having higher persistency of lay produced more eggs than those with poor persistency. Housing system can also result in variability in performance of laying hens. North (1984), Horne-Van and Van-Horne (1994) and Moorthy et al (2000) found better egg production performance of layers reared in cages than on deep litter (floor rearing).

The present study was undertaken to document egg production parameters and study associated factors affecting egg production performance of commercial laying hens in Chakwal district, Pakistan.
 

Materials and methods

Data source and prediction of sample size

This study was undertaken during the years 2000-2001 to investigate egg parameters and egg production performance of commercial layers in Chakwal, Punjab, Pakistan.  Sample size for the study was determined by calculating the coefficient of variation from the data generated in the same area by Tariq et al (2000). Maximum coefficient of variation observed for total eggs production was selected as an index for estimating sample size to accommodate both maximum and minimum values of variations in other production and economic traits.

The following model, developed by Casely and Kumar (1989) was adopted for determining sample size.

                     K² * V²
                  N =   -----------
                        D²

Where  “N” was sample size, “K” the normal deviation at 95% confidence interval, “V” the coefficient of variation of the selected variable and  “D” the margin of error assumed to be 0.1. 

Measurements and data structure for statistical analysis

After determining the required sample size, data were collected from 109 randomly selected flocks. Factors studied were stocking density, hen-housed, rearing system, cage vs. floor rearing of bird, hygienic measures adopted, vaccination practice, daily mortality (if any) during egg laying period, age at point-of-lay, age at peak-of-lay, daily egg production and voluntary culling during growing and laying periods. Hygienic status of the farm was categorized as good, average and poor on the basis of floor and house construction, vicinity of the farm, distance between sheds or other dwellings, housing conditions, all-in, all-out system, cleanliness and sanitation of equipments/houses and disinfecting procedures / adopted. All farmers were following standard vaccination and debeaking programs advised by the chick suppliers.  Stocking rate of laying hens was assessed on the basis of number of chicks or birds/m². Deviation above or below the recommended level was grouped as over or under utilization of the available space.

Data analysis

Data were analyzed using relevant statistical methods of data analysis, namely, weighted mean procedures, general linear model (GLM) procedures, production functions and regression procedures.

Weighted means or averages

To account for the wide variability in flock size, weighted means were calculated instead of simple averages, using the following equation;

X  =  S WiXi/SWi   

 Where  “X “ was weighted mean, “Xi “ the variable, “ Wi” the weight factor/number for a particular variable.

 The effect of density of birds/m², hygienic condition of the farm, strain of chicken, flock size, cage vs. floor rearing and system of housing on hen-day egg production of egg type layers maintained in Chakwal was studied. The following statistical model was constructed adopting the procedure of Steel and Torrie (1981):

                    Y_ijklmno = ΅ + a_i + b_j + c_k + d_l  +  e_m  + f_n  + (axb)_ij  +  g_ijklmno  

Where “Y_ijklmno“ was the response variable, “΅” the population constant common to all observations, “a_i“ the effect of i-th hygienic condition on the farm (i= poor, average and good), “b_j“ the effect of j-th stocking rate in terms of birds/m² area in the shed (j= more than required number of birds/m², optimum number of birds/m² and less than required number of birds/m²),  “c_k“ the effect of k-th rearing system (k = brood-grow-lay house, brood-grow and lay house, brood and grow-lay house), “d_l” the effect of l-th cage vs. floor rearing system (l= cage and floor), “e_m” the effect of m-th flock size (m= small; ≤10,000, medium; >10,000<20,000 and large; >20,000), “f_n” the effect of n-th strain of chicken (n= Babcock, Nick-chick, Hyline and Hisex), “(axb)_ij“ the interaction between i-th hygienic condition and j-th density of birds/m² and “g_ijklmno” the residual term associated with each Y_ijklmno, normally, independently and identically distributed with mean zero and unit variance.

A similar model was used to study the effect of aforementioned variables on age at first and peak lay, peak and hen-day lay, egg laying period and hen-housed egg production.

Association between various parameters namely, mortality during egg laying period, voluntary culling, age at first and peak lay, peak and hen-day lay, egg laying period and hen-day egg production was worked out using the following regression model.

                                    Y =  b₀ + b_iX_i + e_i                                                                                           

Where  “Y” was response variable, “b_i “ the partial regression coefficients, “X_i “ the independent variable and “e_i “  the residual term.

The coefficient of multiple determinations "R²" was computed as follows,

                                                R² = (r_y^y)²                                                                                          

Where “R² “ was the coefficient of multiple determination, “r_y^y “ the correlation between predicted and actual values. The coefficient R² was adjusted using the following definition:

                        R² (adjusted) = [(n-1)R² - k]/[n-k-1]                                                                           

Where “n” was the number of observations and “k”  the number of independent  variables in the Model (Wonnacott and Wonnacott 1985).

Results and discussion

Age at point-of-lay and peak-of-lay

North (1984) and Singh and Belsare (1994) reported higher age at point-of-lay and at peak-of- lay than the present findings (Table 1). Tolimir and Masic (2000) found almost similar age at point-of-lay whereas Lai and Kan (2000) reported higher age at peak-of-lay than the present findings. The findings of the present study suggest an earlier age at point-of-lay and delayed age at peak-of-lay in laying hens maintained in Chakwal. 

Flock size, stocking rate and rearing system had no significant effect on age at point-of-lay whereas, strain of the chicken and hygienic conditions on farm had a significant effect. Layers kept in cages attained peak-of-lay at lower age compared with those kept on the floor (Table 2). Hisex layers had earlier age at point-of-lay and peak-of-lay than Babcock (Table 3).  

 Age at point-of lay and peak-of-lay was higher (p<0.05) in laying hens maintained under poor hygienic conditions than those under good hygienic conditions (Table 4). The delay in age at point-of-lay under poor hygienic conditions is attributable to higher mortality and stressful conditions that the laying hens were exposed to. This was also evident from the positive association (b=1.13; p<0.0009) of age at point-of-lay with mortality. Holding other independent variables constant, one percent unit increase in mortality delayed age at point-of-lay by 1.13 days.  Age at peak-of-lay was also found positively associated (b=0.14; p<0.03) with mortality, suggesting that increase in mortality by one percent unit will increase age at peak-of-lay by 0.145days. 

North (1984), Petek (1999) and Kristensen and Sillebak-Kristensen (1999) reported higher egg laying period (>52 weeks) than the present findings (Table 1). The smaller egg laying period in the present study was because of seasonal trends and higher fluctuations in egg prices. Price offered for an egg in summer season was not even compensating the incurred cost on individual eggs as consumption declines during summer season. Customarily people prefer other livestock products like yogurt instead of eggs during summer season. There are no proper processing and egg storage facilities in the country that could provide better option to continue egg production in summer season as well. The farmers usually tried to terminate egg production in summer season and get new flocks in egg production at the end of summer season. Chicks were usually procured from February through May and the same flock was disposed off before May in the commencing year.

Flock size, stocking rate, strain of the chicken, rearing system, cage vs. floor rearing and hygienic conditions on farm had no effect on egg laying period. Egg laying period was positively associated with percent hen-day production (b=2.84; p<0.0008), age at peak-of-lay (b=2.01; p<0.007) but negatively associated with age at point-of-lay (b=-2.07; p<0.001) and mortality (b=-0.545; p<0.1564).  The adjusted R² of the fitted model was 31.4%. Holding other independent variables constant, a 1% unit increase in percent hen-day egg production and one-day increase in age at peak-of-lay, increased egg laying period by 2.84and 2.01days, respectively.  On the other hand a 1% unit increase in mortality and delay in age at point-of-lay by one day reduced egg laying period by 2.07and 0.54days, respectively.

Percent hen-day egg production

Akyildiz et al (1993) reported lower percent hen-day egg production (67.3%), whereas Tanaka (1993), Kristensen and Sillebak-Kristensen (1996) and North (1984) found higher values (72.5, 74.5, 73%, respectively) than the present findings. The smaller percent hen-day egg production in the present study could be attributed to poor management and hygienic conditions on farms. Percent hen-day egg production was negatively associated with age at point-of-lay  (b=-0.11; p<0.02), age at peak-of-lay (b=-0.09; p<0.68) and mortality (b=‑0.31; p<0.014) but positively associated with peak percent lay (b=0.13; p<0.4). The adjusted R² of the fitted model was 21.4%. Holding other independent variables constant, a 1% unit increase in mortality, delay in age at point-of-lay by one day and reduction of one percentage unit  in peak percent lay, reduced percent hen-day egg production by 0.11%, 0.091% and 0.32%, respectively. An increase in percent hen-day egg production by 0.14% was obtained with one percent unit increase in peak percent lay.

Flock size, cage vs. floor rearing, hygienic conditions on the farm and stocking rate had a significant effect (p<0.02) on percent hen-day egg production. Large sized flocks were more persistent, having higher peak percent lay and percent hen-day production than small sized flocks (Table 4). Laying hens maintained in cages had higher peak percent lay and percent hen-day egg production than those kept on floor (Table 2). Kumar and Mahalati (1998) and Nair and Ghadoliya (2000) reported better egg-laying performance in large than small sized flocks. Muthusamy and Viswanathan (1998) and Petek (1999) found higher egg laying performance of laying hens in cages than those kept on floor. The higher percent hen-day egg production in large sized flocks and hens kept in cages could be attributed to better management and rearing environment.

Interaction of hygiene and stocking rate also affected percent hen-day egg production. Poor hygiene coupled with higher stocking rate significantly reduced hen-day lay. Layers maintained under poor hygienic conditions had lower peak percent lay and percent hen-day egg production than those under good hygienic conditions (Table 6). Laying hens maintained at optimum stocking rate were more persistent in percent hen-day egg production as compared to those at a higher stocking rate (Table 5). Probably, laying hens maintained under poor hygiene in overcrowded houses were more exposed to stress and polluted environment that could have caused deterioration in their performance.

.Strain of the chicken and rearing system had a significant on percent hen-day egg production. Although, Nick-chick had a higher peak percent lay than Hisex, Hisex was more persistent in percent hen-day production than Nick-chick (Table 3). Differences in percent hen-day egg production among various strains of chicken were also reported by North (1984) and Lai and Kan (2000). Percent hen-day egg production was significantly higher for laying hens in brood-grow and lay houses than those in brood-grow-lay houses (Table 7).

 

Hen-day and hen-housed egg production

North (1984) reported higher hen-housed and hen-day egg production during 52 weeks of production period than the present findings. Hen-day and hen-housed egg production in the present study was for 241 days (34.5 weeks) compared with 52 weeks for the study reported by North (1984). Nevertheless, the observed hen-day and hen-housed egg production could be considered higher as there was a difference of  71 eggs in about 117 days period.  Hen-day egg production was negatively associated with age at point-of-lay (b=‑0.40; p<0.08), peak percent lay (b=‑0.066; p<0.94) and mortality (b=‑1.26; p<0.028) but positively associated with percent hen-day egg production (b=1.45; p<0.001), laying period (b=0.47; p<0.53), peak percent lay (b=0.61; p<0.42) and voluntary culling (b=0.33; p<0.71). Adjusted R² of the fitted model was 67.2%. Findings of the present study suggested that higher age at point-of-lay, peak percent lay and mortality reduced hen-day egg production. On the other hand increase in percent hen-day egg production, egg laying period, peak percent lay and voluntary culling resulted in an increase in hen-day egg production.

Flock size, cage vs. floor rearing, strain of the chicken, stocking rate and hygienic conditions on the farm had a significant effect on hen-day and hen-housed egg production. Significantly higher hen-day, and hen-housed egg production was obtained in large than small sized flocks (Table 6). Significant differences were also found in hen-day and hen-housed egg production among laying hens produced either in small or medium sized flocks. Ames and Ngemba (1986), Kumar and Mahalati (1998), Nair and Ghadoliya (2000) and Farooq et al (2001) reported better egg production performance in large than small sized flocks. Significantly higher hen-day and hen-housed egg production was observed for egg laying hens kept in cages than those kept on floor (Table 2). North (1984),  Horne-Van and Van-Horne (1994), Muthusamy and Viswanathan (1998) and Petek (1999) reported higher egg production of layers in cages than those kept on the floor. The findings of the present study suggested better management and appropriate rearing environment for layers in large flocks kept in cages.  

Higher hen-day and hen-housed egg production was found for Hisex than Babcock (Table 3). Differences in hen-day and hen-housed egg production for Nick-chick and Babcock were also significant. North (1984), Petek (1999) and Tolimir and Masic (2000) also found strain differences in hen-day and hen-housed egg production. Hen-day and hen-housed egg production was higher under brood-grow and lay rearing system than under brood-grow-lay rearing system (Table 7).  

Significantly higher hen-day and hen-housed egg production was found under good than that under poor hygienic conditions on farm (Table 6). Differences in hen-day and hen-housed egg production under poor and average hygienic conditions on farms were also significant. . Significantly lower hen-day and hen-housed egg production was found at lower stocking than at optimal stocking rate (Table 5). Non-significant differences were found in hen-day egg production at higher or lower stocking rate. Adams and Craig (1985) and Carey et al (1995) also reported poor egg production performance of egg laying hens at a higher stocking rate. Interactions  between hygienic conditions on farm and stocking density of birds also had a significant influence on hen-day and hen-housed egg production. Considering both qualitative variables as dummies in the model after defining hen-day egg production as function of hygiene and stocking density, a decline in hen-day egg production was found with increased stocking rate and hygiene approaching poor from good.

Culled eggs

Incidence of broken eggs was higher on floor than in layers kept in cages (Table 2).  Adams and Craig (1985) and Carey et al  (1995) also found higher incidence of broken eggs in floor-reared laying hens than those kept in cages. The higher proportion of culled eggs on floor rearing could be attributed to poor management.

Conclusions and recommendations

Age at point of lay was lower than most of the reported research findings.

Better egg production was found for;

• Hisex strain of layer than Babcock, Nick-chick and Hyline

• large than small sized flocks

• layers kept in cages than on floors

• layers reared in brood-grow and lay houses

• flocks maintained at optimal stocking density under better hygiene as compared to flocks maintained at a higher stocking rate under poor hygiene. 

Higher stocking density coupled with poor hygiene had adverse effects on egg production performance. Maintaining larger flocks in brood-grow and lay houses under good hygiene and use of cages instead of floor housing will improve egg production performance of laying hens in Chakwal district.
 

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 Received 30 January 2002

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