R.D. Slade1
A.Y. Yalda2
1University of Leeds, UK
2Baiada Poultry, Melbourne VIC, Australia
Wet feeding of broilers from 11 days has consistently improved weight gain and/or efficiency. Two experiments were conducted to investigate wet feeding at younger ages. Introducing wet food at 3 days improved weight gain and efficiency to 19 days compared to dry feeding throughout, with introduction of wet feed at 7, 10 or 13 days giving intermediate results.
In the second experiment, in which chicks were fed either wet or dry from arrival to 10 days and all were then dry-fed to 21 days, the wet-fed birds maintained their higher food intake and weight gain when subsequently dry-fed. Wet feeding of chicks is feasible and can give significant advantage.
Introduction
Wet feeding has been shown to give significant improvements in growth rate and/or efficiency of broiler chickens (Forbes, 2003) but there are some major barriers to the commercial implementation of this method. One of these is a lack of knowledge as to whether newly-hatched chicks can be wet-fed as previous experiments have usually started wet feeding at about 11 days post-hatching. It may be convenient from a management point of view to commence wet feeding as soon as possible, or it might only be possible to wet feed at an early age when the feed intake is low enough for the food to be mixed with water and delivered to the birds by hand.
In preliminary trials we observed that day-old chicks became very dirty with food if it was offered in containers into which the birds could climb; however, when small troughs were used that prevented this, they started to consume wet food immediately it was offered and at 5 days of age the chicks fed wet food were heavier than those fed dry food by 15 g. In the first experiment reported here broilers were fed dry food from arrival and this was replaced by wet food at different ages in different groups, from 3 to 19 days. In the second experiment wet or dry food were offered from arrival to 10 days and subsequent performance on dry food was followed to 21 days.
Experiment 1
Ninety day-old male broiler chicks were divided into 15 groups (6 chicks each) and allocated to 5 treatments each replicated three times. DRY birds were fed dry feed (Dalgety broiler starter) throughout; WET3, WET7, WET10 and WET13 were provided with wet food (2 kg water/kg feed, sufficient to give the consistency of sloppy porridge) from 3, 7, 10 and 13 days, respectively, and the experiment finished when the birds were 19 days of age. Wet food was prepared 2 or 3 times a day and given to the birds without soaking.
It will be seen from Table 1 that there was an increase in weight gain during the four days after starting wet feeding and that this advantage was maintained for the rest of the experiment. At 19 days WET3 and WET7 were significantly heavier than DRY. Feed intake (expressed as air-dry feed) was not significantly affected by treatment but tended to be higher with the wet feeds, particularly at the end of the experiment. Feed efficiency was improved in almost every case once wet feeding had been introduced, but in no case was this statistically significant, because each mean is based on only three observations. Over the whole period of the experiment the improvement was 13%, comparing DRY with WET3. The other groups were intermediate in efficiency. Carcass weight was significantly increased by feeding wet diets.
Experiment 2
Ninety-eight day old female broilers were divided at random into two equal treatment groups, DRY and WET, each of 4 replicates. Both treatments were fed a wheat based commercial starter crumb ad libitum (crude protein, 190 g/kg; crude fibre, 45 g/kg; total oil, 30 g/kg). WET diets were mixed daily with 2.0 kg tap water per kg air-dry food; refusals were collected the following day, heated to constant weight at 1000C.
From 10 days of age both treatment groups were fed starter crumbs in air dry form. Excreta were collected on days 5-7, 12-14 and 19-21 for determination of approximate DM retention. At 10 days and 21 days of age 12 from each treatment group were killed and dissected for body analysis.
Feed intake to 10 days were similar for both treatments but LWG and FCE were significantly higher (P<0.05) for wet fed birds (Table 2). Following the change to conventional dry diet, the feed intake of the WET treatment birds remained high. Apparent DM retention remained similar for both treatments throughout the trial. At 10 days body and carcass weights of WET treatment birds were significantly greater than for DRY control, an effect that persisted to 21 days.
Total empty weight of the intestinal tract was significantly greater in WET treatment birds (+3.19 g) mainly due to increases in mean crop, gizzard and duodenum empty weights (+ 0.22 g, + 1.28 g, + 0.70 g, respectively). By 21 days there were no significant differences in intestinal tract measurements although mean gizzard and duodenum weights still tended to be elevated in wet fed birds (+ 2.5 g and + 0.86 g, respectively). Viscosity of proximal SI digesta samples from wet fed birds on day 10 were significantly lower than those from control as were the pH values of samples from the middle and distal thirds. No significant differences were found in SI digesta viscosity or pH of initially DRY and WET fed birds on day 21.
Discussion
The results of the first experiment show that growth and efficiency are improved when the feed is given in the wet form from 3 days of age, to a similar extent to that previously shown with older broilers. In this experiment the feed was mixed with water two or three times per day in view of the high level of feed intake and the small size of the troughs used. The fact that efficiency was improved by such a large margin suggests that it is not necessary to soak feed for a long time, as confirmed with older birds (Yalda and Forbes, 1996).
In the second experiment the improvement in growth due to wet feeding was accompanied by reduced digesta viscosity, previously associated with a reduction in the anti-nutritional effects of non-starch polysaccharides present in cereal based diets (e.g. Philip et al., 1995). One possible mode of action was reported by Yasar and Forbes (1999) who noted that a significant reduction in crypt cell proliferation rate (CCPR) paralleled a similar decline in digesta viscosity to that reported here, representing a saving in terms of bird maintenance and therefore increasing the efficiency of food utilisation, as observed here.
In the absence of any significant differences in FCE, gut measurements or viscosity, the mechanism by which body and carcass weight advantages persist beyond the wet feeding period might involve the relationship between body weight and feed intake.
Proportional to body weight, feed intake for WET and DRY treatments respectively was 0.89 and 0.84 at 10 days and 0.86 and 0.84 at 21 days. Thus the increased body weight of wet fed birds at 10 days would appear to promote higher feed intake and faster growth to 21 days.
These results suggest that it might be worthwhile providing commercial chicks with wet food initially, when their food intakes are very low and such provision would not be expensive in terms of machinery or labour. Care must be taken, however, that chicks can easily obtain food without being able to climb into the feeders during the first few days.
Where an investment in automated wet feeding has been made, its use can commence as soon as the birds are able to eat from the troughs.
References
Forbes, J.M. (2003). Avian & Poultry Biology Reviews, 14:175-193.
Philip, J.S., Gilbert, H.L. and Smithard, R.R. (1995). British Poultry Science, 36:599-603.
Yalda, A.Y. and Forbes, J.M. (1996). British Poultry Science, 37:797-807.
Yasar, S. and Forbes, J.M. (1999). British Poultry Science, 40:65-76.
From Proceedings of the "17th Australian Poultry Science Symposium", New South Wales, Australia.
