Broilers perform according to their genetic make-up and the environment where they live. The environment in a broad sense, is the outside temperature, nature of housing, the type of feed and every thing other than the genetics.

The birds with better genetic make-up should give better results, naturally. But the environment dictates the performance. This is more true, when they are subjected to unfavorable environment. The actual performance is not the same in both the climates. In another way, there can be change in the ranking of genetic groups in different climates. "A" outperforms "B" in one climate and falls behind "B" in another climate.

Poultry breeders in western countries have been breeding the birds for a century. Optimum environment is provided for the breeding stock. This is done considering the cold climates they work in. There is also a fear of getting in to health problems for the valuable breeding stocks, while subjecting the birds to unfavourable climate. The poultry rearing at the farmer's level also is not much different in those countries. Hence, the birds bred under moderate climates perform well at the farmers with similar climates.

Hybrids produced from these stocks are distributed worldwide. Many of the countries around the Equator with hot climates have adapted open-sided houses exposed to wide variation in climates. In spite of the best efforts of the farmers, the temperatures in summer may go to 40°C and above and is near 0°C in winter. Wide variation in the level of performance is found between the seasons. Developing countries have the problem of capital expenditure on climate controlled houses and do not have constant supply of the power to run them.

Another major environmental factor is the nutrition given to the birds. Feed ingredients like maize were available in abundance in advanced countries and the maize fed to the broilers is of excellent quality and free from mycotoxins. Third-world countries give least-cost rations consisting of lower quality maize or a mixture of many grains. All put together, the feed will not have similar energy levels and some of ingredients are bound to have some toxins. The low level of toxins may not kill the birds but affect the performance by making the other nutrients unavailable for performance.

Countries like India do not have climate-controlled houses. The best quality of the maize and soya are not available for poultry. Least-cost rations are formulated by the qualified nutritionists. They try to meet the requirements through multiple sources keeping the price in mind. There is a possibility that the feed has low level of toxins despite their best efforts.

In India, there are breeding programmes to improve the birds through the same techniques of selective breeding and hybridisation. The breeding birds subjected to selection are evaluated in the same environment as on the poultry farm: houses are open-sided and house temperatures go to 40°C and above in summer. Biosecurity measures are adapted to keep the stocks away from specific bacterial and viral diseases.

India imports breeding stock from the western breeders. There is an opportunity to compare both the birds under the same climate and feed. The integrators, who operate in larger scale and invest more money, can provide better management and better feed to get the optimum results. The integrators employ feed technology like steaming and pelleting. The farmers have small grinders and mixers to make mash feed on their own farm. Some of them purchase concentrate containing all ingredients other than the grains. They add grain and make mash feed. This feed is 15 to 20 per cent cheaper for the farmer.

The Experiment

Indbro conducted a grow-out trial with the aim to compare western broiler breeds bred under moderate climates with Indian birds bred under open-sided housing exposed to wider range of climate and ordinary mash feed.

Two breeds were tested:

• A. Birds bred under moderate climates and imported in to hot climates, and
• B. Birds bred under hot climates with ordinary locally available mash feed.

The three environmental situations were:

• 1. Hot climates where the day temperatures crossed 40°C throughout (April and May), fed with good quality processed feed procured from an integrator; the feed is as per the recommendation of breed A. The feed is steamed and pelleted; pre-starter crumbs with 22.5 per cent protein and 3,000kcal energy for the first 10 days; starter crumbs with 21 per cent protein and 3,100kcal from 11 days to 23 days; finisher ration, steam-pelleted, with 19.5 per cent protein and 3,300kcal from 24 to 40 days.
• 2. Hot climate same as Situation 1 and fed with average quality mash feed; starter feed with 21 per cent protein and 2,760kcal energy up to 23 days in the form of mash feed; finisher feed with 19.5 per cent protein and 2,900kcal energy from 24 days to 45 days. These birds took five more days to marketable weight.
• 3. Moderate climate, the temperature never exceeded 34°C (June-July) and birds were fed with good quality processed feed, as in Situation 1.

The chicks for trials 1 and 2 were produced from the hatching eggs of different breeds in the same hatchery. All the chicks, identified with de-toeing marks were placed in the same house with four compartments in the same house. The trial was conducted in April, extending to May in 2011. The peak day temperatures were 40°C and above. The poultry house was open-sided. No cooling was carried out but a gunny curtain was provided for 3ft on the sides, kept wet with a drip pipe during the day. Birds were fed early in the morning and in the evening. One group of both the breeds were fed with good quality processed feed and the other group with ordinary mash feed. Feed records were maintained for each group separately. All the birds in this trial were weighed and the sex was recorded at the time of weighing. The weight gain of the birds was late on mash feed. Weighing was carried out on the 45th day. The individual weights were pooled to get the flock data.

Trial 3 was taken up on a larger flock of the same breeds on a different farm during July 2011. Flocks of 5,000 chicks procured from different hatcheries on the same day were housed in two houses, adjacent to each other. The climate was moderate and the temperatures were around 34°C.

The same commercial feed, given in Trial 1 was given for all the birds and the same feeding pattern was followed. Because it was a commercial flock, individual weights were not recorded. All the birds were weighed and sold on the same day. The flock record of mortality, feed consumption and sale of the birds was the basis. The average weight is calculated on the 100 per cent flock weight obtained from sale records.

Results

Discussion

Feed consumption and weight gain

The five-day delay on mash feed in trial 2 was expected due to the outside temperature and nature of the feed. The feed consumption of Breed A was 3320g in hot climates in sharp contrast to its consumption of 4400g when the climate was moderate (trial 3). Body weight was down by 1000g in unfavourable weather and low quality feed (1388g versus 2297g). Birds bred under hot weather (Breed B), on the other hand, managed to eat similar quantity of feed in all the three situations (3300 against 3700g). The variation in body weights was less in both the climates (1798 to 1944g).

The daily gain of the birds bred under moderate climates (A) was lower than B when the climate was hot (40.6 versus 48.3) and when the feed quality was of lower quality (30.8 versus 40.0). There was a complete reversal when the climate was very good along with good quality feed (57.4 versus 48.6).

Feed conversion ratio (FCR)

FCR was calculated as total feed consumed ÷ total chicken produced by the birds alive at the end of the trial. The FCR figures in this trial are influenced by the dead birds whose weights were not included but the feed consumed was included. However, this is the practical way of FCR calculations, the net results was FCR going very high for the birds bred in moderate climates (A) due to higher mortality, when compared to the birds bred under moderate climates (B). FCR with low quality feed is higher than good quality feed. The price of good quality feed is also very high. It is interesting to see that the FCR of the B are marginally better than A when the climates and feed are favourable (1.92 versus 1.93). Birds bred in hot climates excelled the other in hot climates (1.64 versus 2.05) and when coupled with lower quality feed (1.82 versus 2.39).

Mortality

The depletion of the flocks bred in moderate climates was higher (23.2 per cent and 12 per cent) than that of the birds bred under hot climates (8.0 per cent and 3 per cent). The depletion was same in both the breeds when the climate was good (5.8 versus 6.5).

Flock uniformity

There was a difference in weight gain of the individual birds in hot climates and low quality feed. The coefficient of variation was calculated by using the individual weights (standard deviation *100/Mean). The birds bred in moderate climates showed high variation (17 to 31 per cent), whereas the birds bred under hot climates showed normal variation of the broiler flocks (9.5 to 13 per cent). Both the flocks were produced on the same day, had same vaccination programmes and were reared in the same pen. The number of condemnations at sale (i.e. birds weighing less than 1kg) was higher in the flocks bred in moderate climates (28 and 69 against 1 and 4).

The meat yield of the birds bred specifically for the de-boned markets in the west had better breast meat percentage and the total meat percentage. The superiority of the birds bred under moderate climates was up to two per cent in good quality feed, which became negligible with low quality feed. The same was not measured under moderate climate and good feed.

Conclusions

Dr Kotaiah concludes that birds bred under hot climates and on average feed perform well under similar climate and do much better when good feed and good climate is provided.

Birds bred under a moderate climate have good genetic potential to perform in moderate climates but perform less well when the climate is unfavourable.

The reversal in ranking in final bodyweight and daily weight gain is mainly due to the ability of the bird to maintain the feed consumption without succumbing to mortality, he says.

The variation in the birds bred under moderate climate is abnormally high under unfavourable circumstances.

The mortality of the flocks bred under moderate climates was high, resulting in a poor overall feed conversion efficiency.

Summing up, Dr Kotaiah adds that birds can be successfully bred under hot climates and these birds perform better in both the climates.

January 2012