Tags: Hatching | Blog
20 March 2008,
A few months ago, I visited a new customer in Latin America who had only recently switched from multistage to single stage incubation. A week before my arrival, the hatchery manager informed me that having applied the set points I had recommended to start with, taking the requirements of the specific breed into consideration, he was generally quite happy with the results being achieved in the hatchery.
Hatchability was 3% better than before, although there seemed to be a higher incidence of first week mortality among the single-stage chicks in the broiler farm, when compared with the multistage chicks. He also informed me that chick weight seemed high, at 71 % of original egg weight -and now he was experimenting with reduced relative humidity set points in the setter.
As soon as I arrived at the hatchery, late in the afternoon, I was taken to the broiler farm where chicks of one and half days old were housed at that time.
In the house with chicks from the original multi stage setters, I saw over-active chicks, running around in groups. This, explained the broiler farm manager, was considered normal. He complained that by comparison, the chicks from the single stage incubators in a second house were slow and inactive. I understood his reasoning: he had received over-active chicks for many years now, and for this hatchery – that represented normal behaviour for the chicks.
However I explained to him that this kind of ‘over-activity’ was in fact related to heat stress experienced by the embryo’s during the last days of incubation - and that this behaviour would not contribute positively to production results for the broiler farm.
In the second, ‘single-stage’ house, I observed chicks either at rest or drinking from the nipples. This, I explained, was far preferable behaviour to the over-active chicks we had seen in the first house. However even among these single-stage day-and-a-half olds, mortality was already as high as 1.65% and the broiler farm manager expected this to continue to rise to 2.5-3% by day 4 or 5. On handling a good sample of these chicks, I found them to be quite ‘full’, with quite a number of them showing open navels. Something was obviously wrong in the hatchery, as all the other factors that may have explained the difference between the two houses were more or less the same.
That evening during dinner, we talked ‘chicks’ of course. The hatchery manager told me more about how he ran the hatchery. The multistage routine was to set eggs at 5.00am, taking-off chicks three weeks later at 3.00am: an incubation time of 502 hours. This early start was, he explained, to ensure that the chicks were ready for transport during the cool morning hours.
Since the change-over to single stage incubation, the hatchery followed the same routine. However, the setters were started seven hours earlier on the preheating programme. When I asked how the (single-stage) chicks appeared at the moment the hatchers were opened, he admitted that indeed, some chicks were still wet.
I explained that 502 hours incubation time is acceptable for multistage incubation, where the first chicks hatch earlier and the hatch window is much wider - and delaying chick take-off leads to the dehydration of the early hatched chicks.
In single stage incubation, the hatch window is much narrower (12 – 24 hours) - especially after preheating correctly and virtually all chicks will have hatched after 504 hours incubation time. A look through the window might suggest that the chicks are ready for take-off, especially because the active, fluffy chicks move towards the light. However, an additional 8 – 10 hours is still required for drying the chicks. When chicks are pulled too early, those that are still wet can easily become chilled - and this can contribute to increased mortality on the farm.
The next morning, I was up bright and early to be present during chick take-off at 3.00 am. On opening the hatchers, I looked in several baskets and noticed an average of 25 – 30 chicks with a wet appearance, indicating that some of them had fully hatched only a few hours before.
I could do no more at that moment than ask the hatchery manager to delay take-off by four hours, to give the chicks a chance to dry. In the hatcher room next door, chicks were expected a full day later and here - as an emergency measure – we increased the temperature set point from 36.7ºC to 36.9ºC: an increase of 0.4 – 0.5 ºF. At the same time, we agreed that these chicks should be pulled three hours later. Any longer was not possible, due to logistics and labour planning. However this hatch yielded 2% more saleable chicks - and after one day in the broiler farm, mortality was around 0.13 % in one house and around 0.26% in another. It was a significant improvement! However I still felt that the chicks’ bellies were rather too full, which continued to indicate insufficient weight loss.
The hatchery manager accepted that the setters should be started earlier, finetuning timing based on observations during consecutive chick take-offs. The aim should be to ensure that 95% of the chicks are dry, with only 5% of chicks showing limited wet feathers in the neck area. He also agreed to raise temperature set points slightly around days 7 – 10, as egg shell temperatures were showing slightly below optimum in the hatchery’s records. Increasing set points thus would also, I assured the hatchery manager, increase weight loss sufficiently to reduce the incidence of thick bellies and open navels.
Based on the hatchery manager’s experiences with single stage incubation so far, he was now confident of achieving at least 5 % more chicks surviving the first week in the broiler house, partially by improved hatchabilty – and definitely by reducing the number of culls and mortality.
For this operation of 12 million chicks per year, this 5% equates to 12,000,000 x 5 % x € 0.25/chick = € 150,000 / year. Each additional one per cent added to this will produce an further € 30,000 – and this doesn’t take into account the added effect of improved broiler performance due to a better start in life. Per point of improved FCR, 22 grams of feed is saved for each broiler: 12,000,000 x 22g = 264,000kg of feed saved across the entire operation each year. And with inflated feed prices continuing, this is an important factor, not to be ignored.