Interest of the use of quantitative feed restriction in the production of heavy broilers

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Volume 35, Article 4

[Volume 35, Article 4]

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C. Kouki ¹

R. Bergaoui ¹

¹ Department of Animal Production, National Agronomic Institute of Tunisia, University of Carthage.

Abstract - 200 chickens, one day old, of Hubbard Classic heavy strain were distributed in 5 groups. A Quantitative feed restriction was used for broiler chickens slaughtered at different ages to estimate his impact on their performances, breast and thigh yields. Feed quantitative restriction (75% of a control group C fed ad -libitum during the experiment) was applied for two weeks as : R42 _21-35 chickens restricted from 21 to 35 d of age and slaughtered at 42 days , R49 _28-42 chickens restricted from 28 to 42 d and slaughtered at 49 days ; R56 _35-49 chickens restricted from 35 to 49 d and slaughtered at 49 days ; R63 _42-56 chickens restricted from 42 to 56 d and slaughtered at 63 days. After one week of re-feeding a sample of broilers of each group (C, R42, R49, R56, R63) was slaughtered in order to determinate the weight of the carcass, thigh, breast and to calculate the fat yields. Restricted broiler chickens R63 _42-56 have improved their feed conversion during the re-feeding period and had a similar body weight than those of ad- libitum group. Restricted broilers R56 and R63 improved significantly the gain weight during the re-feeding period. At 63 days of age the R63 had a similar breast and carcass weight to that of ad-libitum group contrary to others group having a breast and carcass’s weight significantly lower than ad-libitum broilers. The breast, thigh‘s and carcass yields of restricted chickens slaughtered at different age were not affected by feed restriction. This study showed that gizzard fat and abdominal fat weights of restricted group were significantly lower than those of ad-libitum group. However no significant difference between abdominal fat deposition yields of restricted and ad-libitum group to the different slaughtering ages. Mortality by ascites was reduced significantly at late ages (8 and 9 weeks of age) by feed restriction. A slaughter age of restricted broilers of 63 day may be effective for improvement of growth performances and reducing mortality of fast growth broilers breaded to late age for cutting.

Keywords: ascites, quantitative feed restriction, broiler chickens, slaughter age, breast and thigh yields.

1. Introduction

Nowadays, consumers of poultry meat demand faster and easy to bake products with a low fat yield. These products require heavy broilers with high weight of noble parts like breasts and thighs and the intervention of a processing industry. Heavy broiler market for cutting requires production of heavy and late slaughter broilers. However, the increase in the age and weight of the broiler tends to cause problems related to the ascites disease. The incidence of ascites is higher in chickens with high mortality rate during finishing, mostly at warm period of the year, slow weight gain and higher feed conversion (Buys et al 1999). Late slaughter increases abdominal fat deposition (Rabot et al, 1995). Feed restriction can reduce the frequency of the pathologies as ascites (Acar et al, 1995, Jones (1995) , Mcgovern et al (1999) et Camacho et al (2004)). Several studies have shown that feed restriction reduces mortality ( Quarter et al, 1990) and abdominal fat ((Palvink et Hurwitz , 1985 ; Palvink et al , 1986), Zubair et al ,1994). Some studies had been reported that feed quantitative restriction improved feed conversion (Deaton, 1995)) and weight gain (Ozkan et al, 2006). Tumova et al (2002) indicate that feed restriction causes an accelerate growth (compensatory growth) while. Palvink and Hurwitz (1985) demonstrate that early growth restriction of broilers induced by feed restriction improved feed efficiency and carcass quality by decreasing fat deposition.

The objective of this study is to estimate the impact of quantitative restriction applied at different ages which aims to produce a heavy broiler with high performances, high yield’s meat and reduced fat deposition and to demonstrate if feed restriction limit high mortality related to late slaughter.

2. Materials and methods

   1. Exprimental design

The present study was conducted with 200 chickens (one day old) of Hubbard Classic heavy strain produced by a commercial hatchery and with an average weight of 43 g. The chicks were distributed at the first day of age in 5 groups. Chickens received in succession during the whole period of the trial a starting, growing and finishing rations (table 1). The chicks were fed ad-libitum until the age of 21 days. By later, they were transferred to allocate 20 cages on 5 treatments. Each treatment was assigned in 4 repetitions of 20 birds per pen. Feed quantitative restriction was applied as approximately 75% of the control group C fed ad-libitum. The other four treatments were:  R42 _(21-35) chickens restricted from 21 to 35 and killed at 42 days of age, R49 _(28-42) chickens restricted from28 to 42 day of age and killed at 49; R56 _(35-49) chickens restricted from 35 to 49 day and killed at 56 ; R63 _(42-56) chickens restricted from 42 to 56 day of age and killed at 63. Each restricted group was re-feeded for one week after the restriction period. A sample of animals (n=12) of each group C; R42; R49; R56 and R63 were slaughtered respectively at the slaughters ages (42d , 49d , 56 d and 63d). Broiler's carcasses were cut for determination weight and calculation of carcass, thigh, breast and fat yields.

2. Statistical analysis

All data were submitted to analysis of variance using the One –Way Anova procedure of Mintab .Differences among treatments were determined as significant at 5% level by Tukey’s multiple.

3. Results and discussion

   1. Performances

      1. Body weight

Results of body weights are presented in table2 . At ages of 42d and 49d, body weights of restricted groups R42 and R49 were significantly lower than those of control group at the same ages. However, restricted broilers R56 et R63 had at slaughter ages a similar body weights than those of ad-libitum group. Results of our study show that significantly lower weights of R42 and R49 could be attributed to feed restriction applied for two weeks. However restriction on intervals [35d-49d] and [42-56] respectively associated to R56 and R63 had no impact on body weights and restricted broilers had a similar body weight than those of control boilers which were at the same ages.

2.  Feed intake:

3.  

   Table 2 : Effects of feed restriction on body weight (g)
   Age / treatment			Control ad libitum		R42 (21-35)		R49(28-42)		R56(35-49)		R63 (42-56)
   	28d	1162,6a		982,8 b		1154,8 a		1159,1a		1185,1a
   	35d	1758,2a		1431 ,8c		1551,2b		1719,3a		1729,4a
   	42d	2306,8ab		2046,2c		1998,9c		2149,2b		2324,3a
   	49d	2754,1a				2419,0b		2498,16b		2689,6a
   	56d	3263,8a						3066,30a		3142,2a
   	63d	3718,5a								3728,2a
   	a,b ,c–means followed by similar letters in the same lie are not significantly different by Tukey’s test (p <0.05)

   
   

    

The feed consumption of all groups were presented in table 3. During the two weeks of restriction period the 4 restricted groups were restricted 75 % compared to those feeded ad-libitum. Each restricted group was refeeded ad-libitum for one week after restriction period. During re-feeding feed intake of restricted groups were significantly lower than that ad- libitum groups with the exception of the R42 group which had a similar feed intake of that of ad- libitum group.

3. Gain weight and feed conversion 

During two weeks of restriction ‘s period, restricted groups had a gain weight significatively lower than thot of the control group feeded ad-libitum. However R63 group had a similar weight gain at the second week of restriction (table 3).During re-feeding weeks restricted groups R42, R49 expressed a similar gain weight than those of ad -libitum group C. However the restricted group R56 and R63 had gain weights significantly higher than those of ad- libitum group respectively during the re-feeding period .In this case feed restriction improve significantly the gain weight during the re-feeding period of two groups R56 and R63. Feed conversion was improved only for the R63 group which had a feed conversion significantly lower than that of ad -libitum group. However for the other groups R56, R49 and R42 feed conversion were significantly similar to ad- libitum groups (table4). Results showed that feed conversion was also improved among chickens of group R49 during the second week of restriction.

4. Mortality:

The number of chickens dead from 4 to 9 weeks of age is shown in table 7. The mortality was reduced by feed restriction essentially on late weeks of breeding. This finding is concorted with the studies of Acar et al (1995), Jones (1995) and Mcgovern et al (1999). At advanced ages of 8 and 9 weeks, the mortality in the restricted treatments was significantly lower than in the control.

2. Cutting Results  

   1. Carcass, breast and thigh's weights and yields:

Carcasses’ weight of restricted group R42, R49, R56 were lower than those of ad -libitum group, however the R63 group had the same carcass’s weight than that of a control group. Breast's weight of restricted group was significantly lower than that ad-libitum group excepted the R63 group (table 5). Restricted group thigh’s weight was not significantly different among the restricted and ad-libitum groups excepted thigh's weight of R42 group which was significantly lower than that of ad-libitum group. Carcass, breast and thigh’s yields of restricted groups and are not significantly different from those of ad-libitum group on different slaughter age (42d, 49d, 56 d and 63d).

2. Abdominal fat and Gizzard fat

Abdominal fat was affected by restriction in the present study (table 5) which confirms results from studies of Palvink et al(1986) Rosebrough et al (1986) Acar et al (1995) who showed that feed restriction reduced abdominal fat pad weight contrary to these findings Yu et al (1990) and Fontana et al (1993) who observed no differences in abdominal fat weight between ad-libitum and feed restricted broilers. The lowest abdominal fat percentage was observed in restricted birds (table 6). The gizzard fat‘s weight of all restricted groups were lower than those of ad -libitum group.

4. Conclusion

The results of the present study indicate that restriction at late age improve feed conversion and weight gain. So restriction for two weeks applied from 42 day of age to 56 day improve feed conversion and weight gain during re-feeding period and reduce mortality at advanced age. Carcass, breast, and thigh yields were not affected by restriction. Feed restriction reduces abdominal and gizzard fat but has no effect on abdominal and gizzard fat yields. Restriction used in this study may be an alternative to reduce problems of performances and mortality related to late breeding of rapid growth chicken. The present finding showed increasing of slaughter age to 63 day may be effective for improvement of growth performances and mortality of fast growth broilers breeded to late age in order to obtain breast and thigh yields similar to broilers feuded ad- libitum.

5. References

Acar N., Sizemore FG, Leach GR, Wideman RF, Owen RL, Barbato GF .,1995 .Growth of broiler chickens in response to feed restriction regimens to reduce ascites. Poult.Sci. 74 : 833-843.

Camacho M. A., Sua´rez M. E ., Herrera J. G ., J. M. Cuca, and. Garcı´a-Bojalil C. M .,2004. Effect of age of feed restriction and microelement supplementation to control ascites on production and carcass characteristics of broilers. Poult. Sci. 83:526–532.

Deaton J.W .,1995.The effect of early feed restriction on broiler performance. Poult. Sci. 74,1280-1286.

Julan B and Wilson B.,1992. Pen oxygen concentration and pulmonary hypertention induced right ventricular failure and ascites in meat type chickens at low altitude .Avian dis .,36-733-737.

McGovern R.H., FeddesJ J.R., Robinson F.E.,  Hanson J.A., 1999 . Growth performance, carcass characteristics, and the incidence of ascites in broilers in response to feed restriction and litter oiling. Poult. Sci. 78, 522-528.

Ozkan S., Palvink I ., and Yahav S ., 2006 .Effects of early feed restriction on performance and ascites developpement in broiler chickens subsequently raised at low ambient Temperature .j Poultry science association 15 : 9-19,

IncPlavink I ., Hurwitz S.,1985.The performance of broiler chicks during and following a sévère feed restriction at an early age. Poult. Sci.  64, 348-355.

Plavink I ., McMurtry J. P., Rosebrough R. W .,1986. Effect of early feed restriction in broilers – I: growth performance and carcass composition. Growth, Lakeland, v. 50, p. 68-76.

Zubair A. K and Leeson S.,1994. Effect of varying period of early nutrient restriction on growth compensation and carcass characteristics of male broilers. Poult. Sci. 73:129–136.