Stress response differences and disease susceptibility reflected by heterophil to lymphocyte ratio in turkeys selected for increased body weight

Abstract

Three genetic lines of turkeys were compared for their responses to Escherichia coli challenge following dexamethasone injection (Dex) or E. coli challenge preceding transport stress (TS). The turkey lines were a slow growing line selected for increased egg production (Egg line), a fast growing line selected for increased 16-wk BW (F line), and a commercial line (Comm line). At 14 wk of age, the Dex group was treated with 3 injections of 2 mg of Dex/kg of BW followed by airsac challenge with 100 cfu of E. coli. The TS group was given the same E. coli challenge at 1 x 10(4) cfu/bird without Dex treatment, and was subjected to transport stress, including 12 h of holding time in a transport vehicle, 8 d after the challenge. All treated birds and untreated control birds were bled at the same time, which was 1 d after transport and 9 d after challenge with E. coli. The main effect mean (MEM) total leukocyte counts (WBC) and the percentages of eosinophils (Eos) and basophils (Baso) were the same for all 3 lines; however, the MEM percentages of heterophils (Het) and monocytes (Mono) and the heterophil/lymphocyte ratio (H/L) were lower and the percentage of lymphocytes (Lym) was higher in the Egg line compared with the 2 fast-growing lines. Both stress treatments increased WBC, Het, and H/L and decreased Lym in all 3 lines; however, these effects were significantly greater in both fast growing lines compared with the Egg line. Sixteen-week BW was unaffected by either treatment in the Egg line and was decreased by both treatments in the Comm line and by the Dex treatment in the F line. Main effect mean airsacculitis score (AS) was not affected by line and was significantly increased by TS and Dex treatments. Neither treatment affected AS of the Egg line birds, whereas Dex treatment increased AS of the F line, and both Dex and TS increased AS of the Comm line. Mortality was significantly higher in the Comm line compared with the Egg line and was intermediate in the F line. The differences between these lines in their disease resistance and physiological response to stress in 2 stress models suggests that increasing selection for BW of turkeys is accompanied by changes in the stress response resulting in increased susceptibility to opportunistic bacterial infection.

Effects of heat stress on some blood parameters and egg production of Shika Brown layer chickens transported by road

“…The high density in the crates makes it very difficult for the birds to dissipate their heat (Metheringham and Hubrecht, 1996). The increase in heterophils/ lymphocytes ratio due to heat stress is in agreement with studies of McFarlane and Curtis (1989), Huff et al (2005) and Minka and . The H/L ratio has been used as a reliable indicator of stress in birds (Altan et al, 2000), indicating that, in our study, birds from the control group were significantly stressed compared to treated groups.…”

“…, 2 0 0 3 ) t h a t consequently leads to increased morbidity and mortality rates, with substantial economic losses (St-Pierre et al, 2003). It is well documented that changes in hematological values of the heterophil/ lymphocyte ratio (H/L) is a good indicator of stress (Altan et al, 2000;Huff et al, 2005). Several researchers have suggested various ways of ameliorating the deleterious effects of heat stress acting on birds during transportation, such as administering tranquilizers (aminazine) (Anokhin et al, 1991), and nutritional manipulations through the use of electrolytes (minerals, oils and vitamins) (Holik, 2009).…”

Biochemical and immunological responses of young turkeys to vaccination against Ornithobacterium rhinotraheale and different levels of dietary methionine

“…Genetic progress and selection for growth rate, observed in poultry over recent decades, has resulted in reduced resistance to disease (Li et al 1999b, Huff et al 2005. Adequate nutrition, i.e.…”

Opportunities to improve nutrient efficiency in pigs and poultry through breeding

“…The above partitioning rule was able to account for the observations seen on the performance of different genotypes of pigs that have been selected for different growth intensities and then subjected to infection with pathogens such as the Porcine Reproductive and Respiratory Syndrome virus (Petry et al, 2005;Doeschl-Wilson et al, 2009b); the same applies to the prediction of the performance of different poultry genotypes exposed to other pathogens (Yunis et al, 2000;Huff et al, 2005). This also agreed with the suggestion made by Rauw et al (1998) that animals selected for faster growth will be affected more by pathogens when kept in (nutrient) limiting environments.…”