Feeding Program for Heavy Broiler Chickens

The most common age for marketing broiler chickens is increasing and, in the U.S., is approaching 56-60 days for male birds. Furthermore, a market age of up to 80 days is suggested when future directions of the industry are discussed. The same trend will occur in Canada, in order to meet changing needs of processors and eventually for our industry to compete in world markets.

Growing very heavy broilers requires a re-evaluation of nutritional management, because it is neither essential nor desirable to induce maximum early growth rate. The emphasis is on maximizing monetary return, not on maximizing growth rate. Since the major problems likely to be encountered with these birds are metabolic disorders and carcass fatness, the feeding program must be designed to ensure maximum liveability and product quality. Heavy broilers should not be considered simply conventional birds grown to older ages. Nutrition and general management strategies must start at day-of-age, rather than considering the 42-70d period as an "add-on" to a normal grow-out operation.

Acute Death Syndrome (ADS) and skeletal abnormalities are currently of major concern, although ascites will play a more important role in economics of producing heavy birds. To some extent, these problems can be controlled by lighting programs, although our preliminary studies suggest that even with such step-down programs, 8 to 10% mortality occurs in males from 42-80d of age. This "expensive" late mortality must be resolved by nutritional and management programs that allow for slower initial controlled growth, followed by steady increase in body weight to market weight. Five percent late mortality is as economically unacceptable as 10% mortality in 0-42d birds.

The main reason for conducting our study was to identify feeding strategies that reduce mortality in heavy broilers. Broilers were grown to 70d on mash vs pelleted diets, either conventional high-nutrient dense "broiler-type" or low-energy, low-protein diets aimed at slowing down growth. Each treatment was represented by four replicate pens of 30 broilers. At 70d, eight birds per pen were processed, carcass weight ascertained, and then abdominal fat and breast meat removed and weighed.

Growth characteristics and mortality are shown in Table 1. The most striking result is reduction in mortality of birds fed mash vs pellets, regardless of diet type. Feeding mash also resulted in reduced body weight. Body weight was also reduced when the single-stage low-nutrient dense mash diet was given throughout, compared with the conventional three-stage diet series. Mash-fed birds were about one week behind in growth, although mortality was only 2-6% compared to a mean of 15% for the birds fed pellets.

TABLE 1. Body weight, body weight gain and mortality of broilers fed mash or pelleted diets to 70 d
Body weight (g) Body weight gain (g) Mortality
Treatment Texture Die

TABLE 1. Body weight, body weight gain and mortality of broilers fed mash or pelleted diets to 70 d
			Body weight (g)	Body weight gain (g)	Mortality
Treatment	Texture	Diet type	21	49	70	0 to 21	21 to 49	49 to 70	0 to 70	0 to 70
			d (d,%)
1	Mash	Control	618	2485	3850	575	1867	1366	3807	4.2
2	Mash	Low E-F¹	589	2315	3631	547	1726	1316	3589	1.7
3	Mash	Low ND²	543	2251	3571	501	1708	1320	3528	5.8
4	Pellet	Control	764	2839	4166	722	2075	1327	4124	20.0
5	Pellet	Low E-F¹	763	2783	4114	721	2020	1331	4071	13.3
6	Pellet	Low ND²	698	2747	4111	655	2049	1364	4068	12.5
SEM	28	82	132	28	77	119	132	6.1
Orthogonal contrasts
1 vs 4	**	**	**	**	**	NS	**	**
2 vs 5	**	**	**	**	**	NS	**	**
3 vs 6	**	**	**	**	**	NS	**	**
1 vs 3	**	**	**	**	**	NS	**	**
4 vs 6	**	NS	NS	**	NS	NS	NS	NS

¹Low energy diet after 21 d.

²Low nutrient density.

Feed efficiency was calculated in two ways: either accounting for mortality (F:G of survivors only), or not adjusting for mortality as occurs commercially. The system of calculating F:G influenced the results. The poultry industry is most interested in unadjusted F:G (last column, Table 2). In this situation, the best feed efficiency is seen with mash fed birds, regardless of diet specifications. Feed cost per kg weight-gain favoured the mash diets by some 7kg, again mainly because of high mortality with pellet-fed birds.

TABLE 2. Feed intake and feed efficiency of broilers grown on mash or pellet diets to 70 d.
			Feed intake, grams.bird	Feed intake:body weight
Treatment	Texture	Diet type	0 to 21	21 to 49	49 to 70	0 to 70	0 to 21	21 to 49	49 to 70	0 to 70³	0 to 70⁴
			d
1	Mash	Control	944	3873	3908	8725	1.64	2.08	2.88	2.29	2.31
2	Mash	Low E-F¹	946	3814	3972	8731	1.74	2.21	3.02	2.43	2.43
3	Mash	Low ND²	948	3743	3926	8617	1.89	2.19	2.98	2.44	2.45
4	Pellet	Control	1062	4411	4079	9552	1.47	2.13	3.08	2.32	2.44
5	Pellet	Low E-F	1069	4354	4396	9819	1.48	2.16	3.35	2.41	2.54
6	Pellet	Low ND	1106	4236	4325	9668	1.69	2.07	3.17	2.39	2.50
SEM	35	160	206	291	0.10	0.10	.021	0.06	0.06
Orthogonal contrasts
1 vs 4	**	**	NS	**	*	NS	*	**	**
2 vs 5	**	**	**	**	**	NS	*	*	*
3 vs 6	**	**	*	**	*	NS	*	*	*
1 vs 3	NS	NS	NS	NS	**	NS	NS	**	**
4 vs 6	NA	NS	NS	NS	**	NS	NS	NS	NS

¹Low energy diet after 21 d.

²Low nutrient density.

³Adjusted for mortality.

⁴Unadjusted for mortality.

Carcass characteristics are shown in Table 3. Feeding mash resulted in a significant reduction of carcass weight, and yield of breast meat and abdominal fat. For the lower energy diets, using mash vs pellets also resulted in a significant decline in breast yield as a percentage of carcass weight.

TABLE 3. Carcass characteristics of broilers at 70 d. when fed mash or pelletted feeds
				Abdominal fat	Breast meat
Treatment	Texture	Diet type	Carcass wt. (g)	(g)	% Carcass	(g)	% Carcass
1	Mash	Control	3108	101	3.2	657	21.1
2	Mash	Low E-F¹	2974	57	1.9	653	22.0
3	Mash	Low ND²	2927	59	2.0	629	21.4
4	Pellet	Control	3360	137	4.1	730	21.7
5	Pellet	Low E-F	3311	94	2.8	775	23.4
6	Pellet	Low ND	3307	90	2.7	746	22.5
SEM	299	31	0.9	104	2.1
Orthogonal contrasts
1 vs 4	**	**	**	NS
2 vs 5	**	**	**	*
3 vs 6	**	**	**	*
1 vs 3	**	**	NS	NS
4 vs 6	NS	**	NS	NS

Conclusions
Regardless of diet specifications, using mash diets (rather than pellets) reduces mortality in heavy broilers.

Although mash-fed birds were about one week behind in growth, the feed cost was less, mainly due to this high livability.

The main undesirable effect of mash feeding, however, is loss of up to 1% breast meat yield which is of great commercial significance.

Feeding Program for Heavy Broiler Chickens

The Importance of binder agents in Animal Nutrition

Lost in the Market Uncertainty Caused by the Outbreak

Effects of <i>Ganoderma lucidum</i> fermentative products supplementation on growth performances, carcass characteristics and immune response in Native Chickens

The Importance of binder agents in Animal Nutrition