Genotype-by-Environment Interaction with Broiler Genotypes Differing in Growth Rate. 3. Growth Rate and Water Consumption of Broiler Progeny from Weight-Selected Versus Nonselected Parents Under Normal and High Ambient Temperatures

Abstract

One cycle of high-intensity selection on BW was conducted to study correlated effects on performance under high ambient temperature (AT). From a large flock of a commercial sire-line, 3 males and 15 females with the highest BW at 35 d of age were mated and produced a group of 120 BW-selected chicks. Three average-BW males and 15 average-BW females from the same flock were mated to produce a control group of 120 chicks. On Day 17, the two groups were equally divided between two temperature-controlled chambers and housed in individual cages. One chamber was set to a normal AT (NAT; constant 22 C) and the second chamber to high AT (HAT; constant 32 C). Under NAT, the relative advantage of the selected broilers over the controls did not change from 17 to 42 d of age, averaging about 15% for BW gain and 9.7% for feed consumption. These differences were halved under HAT from Days 17 to 28 and were reversed from 28 to 42 d of age, when the selected broilers consumed significantly less feed and gained less BW than the controls. Water-to-feed ratio was measured in each AT treatment. From 28 to 42 d of age, averaged over the two groups, birds under HAT consumed 2.5 g water/g of feed compared to only 1.5 g water/g feed under NAT. The diminished superiority of the selected broilers under HAT led to a substantial genotype-by-environment interaction involving high AT and within-stock genetic differences in growth rate. It appears that broilers selected for rapid growth under optimal conditions do not achieve their genetic potential under high AT. Thus, specific indicators of adaptation to heat, possibly water consumption or body temperature, should be added to commercial selection for rapid growth to improve broiler performance in hot climates.

Efeitos da temperatura e da umidade relativa sobre o desempenho e o rendimento de cortes nobres de frangos de corte de 1 a 49 dias de idade

“…De forma semelhante, Oliveira Neto et al (2000), Deeb & Cahaner (2002) A melhora da CA observada nas aves expostas ao calor neste estudo não está coerente com os dados de Zuprizal et al (1993), que evidenciaram efeito negativo da alta temperatura sobre a digestibilidade verdadeira da proteína e dos aminoácidos de alimentos protéicos (farelos de soja e de colza) em frangos de corte de 28 a 42 dias de idade. Também não está de acordo com a redução das atividades das enzimas proteolíticas (tripsina e quimotripsina) no intestino delgado de aves expostas ao calor verificada por Hai et al (2000).…”

Assessing and Mitigating the Impact of Heat Stress in Poultry

“…The performance of the modern birds, especially broilers is vastly different from the broiler of three decades ago wherein, the modern day broiler grows more than three times faster than the vintage broiler (Havenstein et al, 1994). Modern poultry genotypes developed over the years produce more body heat due to their superior metabolic activity which makes them more sensitive to temperature related environmental changes (Settar et al, 1999;Deeb and Cahaner, 2002). Under circumstances such as high heat, high humidity with reduced air flow or any other extreme stress, the death rate due to physiological changes has increased ( Julian 1993).…”

Influence of Coenzyme Q10 Supplementation in High Energy Broiler Diets on Production Performance, Hematological and Slaughter Parameters under Higher Environmental Temperature

“…Intensive genetic selection for faster growth rate means that modern broiler chickens were susceptible to lots of stresses like heat stress, metabolic stress (Deeb and Cahaner, 2002). The broilers exposed to an environmental temperature of 32°C were subjected to heat stress, which resulted in decreased feed intake by 14%, as compared to those kept at thermo neutral zone temperature; this reduction in feed intake is to reduce metabolic heat production (Sahin et al, 2009).…”