Anyone who has information on the impact of feeding high protein to calorie diet (starter diet throughout ) to broilers raised under temperatures outside the comfort zone on lean and fat mass accretion?
Ali, outside the comfort zone... too hot or too cold?
I would imagine different impacts on welfare and performance?
And why would there be a starter diet throughout regime?
Elwert, thank you very much for responding. As you know, besides genetic makeup, many factors such as age, sex, age of maturity, ambient temperature and nutrient content in the feed impact ME use for maintenance and production purposes. You can control variation due to feed by using one type of diet throughout to see the impact of ambient temperature variation on partitioning of ME for tissue gain. I am looking for information on impact of temp. on tissue accretion.
OK, I see your point.
But the question remains... Would you work below or above the comfort zone range?
We did a project where we grew breeders under conditions allowing us to determine energetic efficiency of the hens. We then did the following project with the broiler offspring. The broilers had temperature telemetry devices surgically implanted in the body cavity to broadcast core temperature every 8 to 10 minutes. Here is the abstract from the project report.
Trial 3 evaluated the performance and efficiency of broilers fed recommended (PIOO) and 10% above recommended balanced protein levels (PlIO) in 4 different thermal environments ranging from thermoneutral (TN)-5°C to TN+ 10°C. Birds fed PlIO had higher maintenance requirements than PI 00 birds (201.4 vs 192.5 kca1/kgO.67, respectively). Birds in the TN+I0 treatment had a core body temperature (CBT) of 41.16°C compared to all other treatments which were all within 0.02°C of 40.95°C. Increased CBT correlated with reduced growth rate and breast muscle yield in the TN+ 10 treatment. Though the differences were small, a small tendency toward PSE-like conditions was observed in females, at increased environmental temperatures, and the higher protein level. There were no differences in drip loss or cooking loss 72 h post mortem. Correlation analysis turned up no relationship between hen efficiency and progeny carcass and meat quality traits. This suggests that there is potential for substantial hen efficiency improvement without sacrificing offspring performance.
Hi Ali;
This was the abstract taken from the portion of research project report dealing with the broilers. We have started to publish the work on the broiler breeders first but the broiler work should be published soon too. The breeder portion of the work was an interesting study in which we we rotated environmental temperatures every 2 weeks to avoid the potential confounding effect of acclimation on long-term egg production and egg size.
Hi Robert,
Thank you very much for the information. I am looking forward to the publications. Some studies suggest prenatal acclimation of chicks as one solution to minimize heat stress effect during summer. Do you think that 2 weeks rotation in ambient temperature is long enough to erase acclimation effect?
An interesting question to which I don't know the answer based on what we did. The results could very well be different in an experiment focussed on prenatal acclimation. This is not something we looked at.
Our breeders came from a single hatch and were randomly reallocated to new temperature treatments every 2 weeks. The goal was to minimize any prior acclimation effects or carry-over effects among time groups. For example, in other work we have observed treatments that affect egg size as birds come into lay to carry on long past the point of sexual maturity. In the current study both egg size and rate of lay were similar across all treatments, suggesting that changing up the treatments at a 14 d frequency was sufficient to avoid confounding by the parameters we had the most concern about.
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