Selection for food conversion in broilers: Direct and correlated responses to selection for body‐weight gain, food consumption and food conversion ratio

1979 ◽  
Vol 20 (1) ◽  
pp. 73-86 ◽  
Author(s):  
R. A. E. Pym ◽  
P. J. Nicholls
1990 ◽  
Vol 51 (1) ◽  
pp. 35-46 ◽  
Author(s):  
R. A. Mrode ◽  
C. Smith ◽  
R. Thompson

ABSTRACTCorrelated responses in two lines of Hereford cattle selected for lean growth rate (LGR) from birth to 400 days of age and lean food conversion ratio (LFCR) from 200 to 400 days of age for a period of 8 years were evaluated. Correlated changes were estimated by two methods: deviation of selected lines from a control line and restricted maximum likelihood. Generally, estimates from the two methods were similar but tended to be more precise for the latter. Statistically significant correlated responses occurred in growth rate in the LGR line and in lean proportion and food conversion ratio in both selected lines. Selection for LGR was accompanied by increases in body weight at various ages in both male and female progeny. In the LFCR line there were little or no changes in body weight for male calves but some increases at certain ages for female progeny. There were no adverse correlated responses detected in reproductive traits such as calving difficulty and calving and pre-weaning mortality.


PLoS ONE ◽  
2016 ◽  
Vol 11 (1) ◽  
pp. e0146141 ◽  
Author(s):  
Cicero L. T. Chang ◽  
Chih-Yao Chung ◽  
Chih-Horng Kuo ◽  
Tien-Fen Kuo ◽  
Chu-Wen Yang ◽  
...  

Author(s):  
N.D. Cameron

An experiment was started in 1984 at Edinburgh and Wye to study responses to divergent selection for lean growth rate (LGA), lean food conversion ratio (LFC) and daily food intake (DFI). This paper measured the selection pressure applied, the responses in the selection criteria and estimated the genetic and phenotypic relationships between the selection criteria with ad-libitum feeding of Large White pigs after four generations of selection.Selection objectives and criteria. The LGA (LFC) selection objective was to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The LGA, LFC and DFI selection criteria had phenotypic s.d. of 27, 29 and 250 units and results are presented in s.d. units.


1983 ◽  
Vol 37 (3) ◽  
pp. 375-385 ◽  
Author(s):  
A. J. Webb ◽  
J. W. B. King

ABSTRACTAn experiment was conducted to show the effectiveness of selection for improved food conversion ratio on ad libitum group feeding. Selection (32 ♀♀ and 8 ♂♂) and unselected control (32 ♀♀ and 16 ♂♂ lines were maintained for seven generations at the rate of one per year. Progeny were fed ad libitum from 27 to 82 kg live weight: boars singly or in pairs, and gilts in litter groups. Selection was on pen average food conversion ratio (food/live-weight gain), recalculated as each pig reached 82 kg.In spite of selection differentials averaging 0·61 s.d. per generation, there was no response (selection minus control) in food conversion at Generation 6 (−0·03, s.e. 0·08). However, there were correlated increases in daily live-weight gain (56, s.e. 18 g), daily food intake (145, s.e. 59 g) and ultrasonic backfat (2·4, s.e. 0·4 mm). In Generation 7, 146 full-sib pairs (male castrate and gilt) were tested on ad libitum or scale (0·77 g/g ad libitum daily food intake) feeding. Line by feeding regime interactions were absent for all traits except killing-out proportion and belly thickness.The increased fatness of the selection line on ad libitum feeding was retained on the scale (2·2 v. 2·4, s.e. 10 mm), suggesting a primary difference in partition of nutrients rather than intake. The selection procedure adopted was not successful in improving food conversion, but no clear conclusions could be drawn from the experiment. Uncertainty remains as to the value of group food consumption measurements in selection programmes.


2021 ◽  
Vol 888 (1) ◽  
pp. 012072
Author(s):  
Siti Khairunnisa ◽  
Sumiati ◽  
Cece Sumantri ◽  
Wiwin Winarsih

Abstract This study aimed to evaluate the effect of zinc supplementation in various diets on the performance and health status of IPB-D2 chickens. Subsequently, about 180 one-week-old IPB-D2 chickens were used in the study and were fed the treatment diets for 12 weeks. Also, this study employed a completely randomised factorial design with six treatments and three replications of ten birds each. These treatment diets included A1, which contained nutrients based on SNI (2013) without Zn supplementation, A2 which is a combination of A1 and 60 ppm of Zinc, B1 which contained nutrients 5% higher than SNI without Zn supplementation, B2 which is a combination of B1 and 60 ppm Zinc, C1 which contains nutrients 10% higher than SNI without Zn supplementation, and lastly, C2 which is a combination of C1 and 60 ppm of Zinc. Furthermore, the data were analysed using ANOVA, and the parameters observed were the body weight, body weight gain, feed consumption, feed conversion ratio, blood profile and the villi surface area of the jejunum. Consequently, the results showed that C2 significantly (P<0.05) increased the body weight and body weight gain when fed to the finisher and grower chickens, respectively. More so, when the finisher chickens were fed the 10% SNI diet, there was an increased body weight gain and also a significantly (P<0.05) decreased feed conversion ratio. Furthermore, the addition of 60 ppm zinc increased haemoglobin significantly (P<0.05), whereas C2 decreased leukocytes significantly (P<0.05) in chicken blood. However, the treatments had no effect on feed consumption in the villi surface area of the jejunum. Therefore, the study concluded that supplementing the IPB-D2 chickens with 60 ppm zinc in a 10% SNI diet resulted in the best performance and health status.


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