Effects of the In Ovo Administration of L-ascorbic Acid on the Performance and Incidence of Corneal Erosion in Ross 708 Broilers Subjected to Elevated Levels of Atmospheric Ammonia

Effects of the in ovo injection of various levels of L-ascorbic acid (L-AA) on the performance and corneal erosion incidence in Ross 708 broilers exposed to 50 parts per million (ppm) of atmospheric ammonia (NH₃) after hatch were determined. A total of 1440 Ross 708 broiler embryos were randomly assigned to 4 treatments: non-injected (control), 0.85% sterile saline-injected (control), or saline containing 12 or 25 mg of L-AA. At hatch, 12 male chicks were randomly assigned to each of 48 battery cages with 12 replicate cages randomly assigned to each treatment group. All birds were exposed to 50 ppm of NH₃ for 35 d and the concentration of NH₃ in the battery cage house was recorded every 20 s. Mortality was determined daily, and mean body weight (BW), BW gain (BWG), average daily BW gain (ADG), and feed intake, as well as feed conversion ratio (FCR), were determined weekly. From 0 to 35 d of post-hatch age (doa), six birds from each cage were selected and sampled for eye erosion scoring. Incidences of corneal erosion were significantly higher at 21 and 28 doa in comparison to those at 14 and 35 doa, and at 21 doa, birds in the saline-injected group exhibited a higher incidence of corneal erosion compared to all other treatment groups. The in ovo injection of 12 mg of L-AA increased BWG (p = 0.043) and ADG (p = 0.041), and decreased FCR (p = 0.043) from 0 to 28 doa in comparison to saline-injected controls. In conclusion the in ovo administration of 12 mg of L-AA may have the potential to improve the live performance of broilers chronically exposed to high aerial NH₃ concentrations, but further study is needed to determine the physiological and immunological factors that may contribute to this improvement.

Impact of dietary supplementation of unsaturated and saturated fatty acids on bone strength, fatty acids profile of thigh muscle and immune responses in broiler chickens under heat stress

BACKGROUND

There have been some reports that supplementation of fat could alleviate the negative effects of heat stress on performance in broilers. However, information regarding compensation for the adverse effects of heat stress with diets differing in fatty acids source on immune system, bone strength and carcass quality of heat-distressed broilers is limited.

OBJECTIVES

The objective of this study was to investigate the effects of diets differing in fat source on performance, immune system, bone strength, and carcass quality of heat-distressed broilers.

METHODS

In a completely randomized design with 4 × 2 factorial arrangement of the treatments, 320 24-day-old Ross 308 chickens, with average initial weight of 1220 ± 10 g were divided into eight treatments included sesame oil, tallow, sunflower oil and palm oil in either 22 or 32 degree of centigrade temperature. The broiler performance of each fat source-treated group was not different in this experiment and decreased significantly in heat stress condition.

RESULTS

Heat stress showed a significant increase on fat, energy and ash content of thigh muscle. Tibia absolute length, width, ash and bone breaking strength were affected by fat source and increased when sesame and sunflower oil were used. Data analysis revealed that hot temperature decreased tibia weight, length, width, ash and bone breaking strength. Heat stress led to decrease of immune system parameters.

CONCLUSION

Results suggest that there is no beneficial effect of broiler performance due to adding different sources of fat in broiler chicken diet under hot condition. Furthermore, the unsaturated fatty acids could improve the profile of fatty acids in thigh and enhance immune responses in broiler chickens.

Single nucleotide polymorphism in avian uncoupling protein gene is associated with thermoregulation in chicks

Avian uncoupling protein (av-UCP) is a key protein for thermoregulation in poultry. A single nucleotide polymorphism (SNP) in the av-UCP gene has been reported in chickens. The purpose of the current study was to clarify the association between this av-UCP gene mutation and thermoregulation in chickens. Wild and mutant type chicks for the av-UCP gene SNP (g. 1270 of the av-UCP gene exon 3 with C to T substitution and amino acid substitution) were exposed to high ambient temperature. Rectal temperature, radiation temperature on the body surface, and the expression of heat dissipation behavior (wing drooping and panting) during heat exposure were measured. In addition, oxygen consumption rate in the thermoneutral zone in wild and mutant type chicks was measured. Changes in wing temperature during heat exposure in wild-type chicks were lower than those in mutants. The latency of continuous wing drooping during heat exposure in wild-type chicks was shorter than in mutant chicks. It was also found that the SNP in the av-UCP gene caused reduced oxygen consumption. These results suggest that the av-UCP gene mutation affects thermoregulation, especially heat production, in chickens.

Modeling net energy requirements of 2 to 3-week-old Cherry Valley ducks

OBJECTIVE

A total of three hundred unsexed ducks were utilized to estimate net energy requirements of maintenance (NEm) and weight gain (NEg) for 2 to 3-week-old Cherry Valley ducks and to establish a model equation to predict NE requirements using the factorial method.

METHODS

To determine the apparent metabolizable energy (AME) of the diet, fifty 7-day-old ducks at approximately equal body weights (BWs) were randomly assigned into five groups that were fed at different levels (ad libitum, 85%, 75%, 65%, and 55% of ad libitum intake), and the endogenous acid-insoluble ash as indigestible marker. The two hundred and fifty 7-day-old ducks were used for a comparative slaughter experiment. At the beginning of the experiment, ten ducks were sacrificed to determine the initial body composition and energy content. The remaining ducks were randomly assigned into five groups (same as metabolic experiment). Ducks of the ad libitum group were slaughtered at 14 and 21-dayold. At the end of the experiment, two ducks were selected from each replicate and slaughtered to determine the body composition and energy content.

RESULTS

The results of the metabolizable experiment showed AME values of 13.43 to 13.77 MJ/kg for ducks at different feed intakes. The results of the comparative slaughter experiment showed the NEm value for 2 to 3-week-old Cherry Valley ducks was 549.54 kJ/kg of BW0.75/d, and the NEg value was 10.41 kJ/g. The deposition efficiency values of fat (Kf) and crude protein (Kp) were 0.96 and 0.60, respectively, and the values of efficiency of energy utilization (Kg) and maintenance efficiency (Km) were 0.75 and 0.88, respectively.

CONCLUSION

The equation for the prediction of NE requirements for 2 to 3-week-old Cherry Valley ducks was the following: NE = 549.54 BW0.75+10.41 ΔW, where ΔW is the weight gain (g).

Thermoregulation responses of broiler chickens to humidity at different ambient temperatures. I. One week of age

Three trials were conducted to investigate the effect of RH (35, 60, and 85%) on thermoregulation of 1-wk-old broiler chickens at different temperatures (35, 30, and 25 degrees C). The response to humidity in rectal temperature and plumage temperature at the back and breast within 24 h after exposure were recorded at 5 time points (1,4,8,16, and 24 h). Humidity affected the thermoregulation of 1-wk-old broiler chickens by redistributing heat within the body at high, low, and thermoneutral temperatures. The redistribution of heat resulted in decreased rectal temperature and increased peripheral temperature, which were, respectively, beneficial and unfavorable at high and low temperatures. These results suggested that feedback effects of surface temperature on core temperature also exist in poultry, as already observed in mammals, and could be induced not only by changed ambient temperature but also by the changes in humidity at high temperature. The disturbance of thermal equilibrium could not be established solely by changes in RT, but rather core and surface temperatures had to be considered. The daily rhythms in rectal and surface temperatures were affected by humidity.

Components of feed efficiency in broiler breeding stock: energetics, performance, carcass composition, metabolism, and body temperature

Two experiments were conducted to identify factors influencing feed conversion in broilers. The first experiment was conducted to develop a test for body temperature (BT) under mild handling stress. In the first experiment, BT was recorded periodically with birds briefly restrained after they had been removed from feed with either continuous lighting or 16L:8D. Body temperature was affected by photoperiod and declined following feed removal. The second experiment was conducted to investigate metabolic-physiologic differences existing between good (G) and poor (P) converting broilers, initially classified in a commercial breeding company's feed conversion (FCR) test. Basal metabolic rate (BMR) and BT were measured at the beginning and end of the FCR test following appropriate time without feed. Heat production (HP) was recorded throughout the study both for BMR calculations and to measure net energy (NE). Excreta were collected for measurement of AME, and at study termination, birds were analyzed for carcass composition. The G and P converters, however, had similar BMR and feed consumption but differed in AME (58 kcal/kg) and total NE (184 kcal/kg). Generally, G and P broilers had similar starting BW, but the G broilers gained more weight on the same amount of feed than did P broilers. The two BT measurements recorded in the present study were correlated with each other. The BT was also correlated with subsequent gain and FCR, indicating potential use as an indicator trait for feed conversion. Further, the data indicated that processes other than basal metabolism (measured as average hourly HP) may impact FCR. These might include variability in fear response during BT measurement or variations in bird activity level.

Avaliação das Propriedades do Ácido Nicotínico no Desempenho e no Balanço Térmico de Frangos de Corte Durante Estresse por Calor

Foram oferecidas 4 doses de ácido nicotínico (AN) na água de beber de frangos de corte, a fim de estudar seu efeito no desempenho e na produção de calor em condições de estresse por calor (6 h de 35º C). As doses foram 15, 100, 330 e 1000 mg/L. Não houve efeito do AN nas doses usadas para ganho de peso, consumo de alimento, eficiência alimentar, consumo de água e temperatura retal. Foram observadas algumas alterações devido ao AN e estresse por calor nos parâmetros sangüíneos das aves. A produção de calor (kcal/h/peso metabólico) diminuiu com o uso de 100 e 1000 mg/L comparados com 15 mg/L. Nas dosagens usadas não foi observado efeito benéfico do AN no controle do estresse por calor.

Effect of environmental temperature on muscle protein turnover and heat production in tube-fed broiler chickens

The present experiments were undertaken to investigate the effects of environmental temperatures on growth, abdominal fat content, rate of muscle protein turnover, and heat production in tube-fed intact male broiler chickens. Plasma concentrations of thyroxine (T4), triiodothyronine (T3), and corticosterone (CTC) were also examined. Chicks (15 d old) were kept at different environmental temperatures (16, 19, 22, 25, 28, 31, and 34 degrees) and given the experimental diet (200 g crude protein/ kg, 13.57 MJ/kg metabolizable energy) by tube three times daily throughout the 12 d experimental period. In the hot conditions, except for 34 degrees, body-weight gain was significantly higher than in the cold conditions. Thus, food conversion ratios (food:gain ratios) were lower when the birds were exposed to the hot conditions other than 34 degrees. Likewise, abdominal fat content was significantly increased, and heat production was lower in the groups kept under the hot conditions other than 34 degrees. The rate of skeletal muscle protein turnover and plasma concentration of CTC were decreased when the birds were exposed to hot conditions other than 34 degrees, suggesting a role of CTC in the regulation of muscle protein turnover. Plasma concentrations of T4 and T3 were significantly decreased as environmental temperature increased. These results clearly show that plasma concentrations of thyroid hormones and CTC are associated with accelerated muscle protein turnover and heat production.

Effects of environmental temperature and heat production due to food intake on abdominal temperature, shank skin temperature and respiration rate of broilers

1. Eight broilers were used to determine the effects of environmental temperature and the increased heat production attributable to food intake on thermoregulatory physiological responses. Heat production, abdominal temperature, shank skin temperature and respiration rate were measured. 2. Heat production rose with increase in food intake and environmental temperature. Abdominal temperature, shank skin temperature and respiration rate also increased but, at 36 degrees C, there was no difference in respiration rate between the different rates of food intake after exposure for 1 h. Also, heat production decreased with exposure time when the birds were exposed to 28 degrees C and 32 degrees C, but increased at 36 degrees C ambient temperature. 3. Although the effect of the increased heat production on thermoregulatory physiological responses was not greater than that of environmental temperature, the increase in heat production enhanced the effect of ambient temperature on thermoregulatory physiological responses. However, with increasing heat production, the greatest response in shank skin temperature was at 28 degrees C, in respiration rate at 32 degrees C and in abdominal temperature at 36 degrees C. 4. These results suggest that, at high environmental temperatures, arranging feeding management to restrict the increase in heat production may alleviate the effect of environmental temperature.

Virginiamycin and caloric density effects on live performance, blood serum metabolite concentration, and carcass composition of broilers reared in thermoneutral and cycling ambient temperatures

One experiment utilizing Cobb x Cobb male broilers was conducted to evaluate virginiamycin (VM; 0, 15, 20 ppm) and diet caloric density (CD; 2,945, 3,200 AMEn/kg) effects on broiler live performance, blood serum metabolites, and carcass composition. The starter period exposed birds to recommended brooding conditions, whereas from 3 to 7 wk birds were exposed to thermoneutral (TN, 24 C) or cycling temperature (CT, 24 to 35 C) environments (E). During the 21-d starter period, VM levels and high CD increased (P < 0.05) BW gain (G) and gain:feed (G:F) improved (P < 0.05) with 20 ppm VM and high CD. During 3 to 7 wk, CT reduced (P < 0.05) most live performance and carcass variables as well as heat production (HP) and energetic efficiency whereas energy content per gram of tissue increased. The main effect of VM and CD on blood serum constituents was not significant; however, CT decreased (P < 0.05) serum Na, K, Ca, Mg, Fe, albumin, and total protein. Within CT, G increased (P < 0.05) with high CD and with the 15 ppm VM combination, whereas within TN, G was unaffected by CD, but increased (P < 0.05) with the 20 ppm VM and low CD combination compared with the control. High CD increased (P < 0.05) BW, G, carcass weight, dressing percentage, carcass percentage fat, carcass dry matter, carcass energy content per bird, HP, fat, and protein gain but reduced (P < 0.05) carcass percentage protein and energetic efficiency. Carcass weight, breast yield, fat, and protein gains as well as dry matter carcass energy content increased (P < 0.05) with VM compared with controls. The reduced (P < 0.05) calorie intake and HP with concomitant increase (P < 0.05) in calorie gain with 20 ppm VM increased (P < 0.05) caloric efficiency. In summary, the results suggest that VM improves bird performance by reducing HP and that reduced HP during high CT improves body temperature homeostasis.

Acclimation effects on fed and fasted broiler thermobalance during thermoneutral and high ambient temperature exposure

1. Two experiments were conducted to quantify heat stress (HS) acclimation effects on heat production (H), evaporative heat loss (E), sensible heat loss (S) and change in heat content (HC) of 24 food-deprived and precision fed broilers. 2. In experiment 1, heat stressed fasted HS acclimated birds (group 1) exhibited lower H (22.6 v. 25.5 kJ/kgW0.66 per h), E (7.5 v. 8.8 kJ/kgW0.66 per h), core body temperature (41.8 v. 42.4 C) and respiration rate (129 v. 160 breaths/min) than nonacclimated controls (group 2). 3. In contrast to the first experiment, precision fed HS acclimated birds (group 1) exhibited a higher H (29.3 v. 28.0 kJ/kgW0.66 per h) and E (10.5 v. 9.6 kJ/kgW0.66 per h) during HS and elevated H during thermoneutral periods than their non-acclimated counterparts (group 2). The elevated H became more pronounced with each successive HS exposure. 4. These results indicate that H increases when broilers are fed, that broilers preferentially dissipate heat as S when environmental conditions permit, and that food and/or energy consumption level markedly influences the bird's capacity to exhibit a HS acclimation response, and in fact has the ability to mask it.

Nicarbazin effects on broiler thermobalance during high ambient temperature stress

Two experiments were conducted to measure the effects of nicarbazin (125 ppm) on heat production (H), evaporative heat loss (E), sensible heat loss (S), and heat content change (HC) of broilers during heat stress. Feed consumption effects on thermobalance were equalized in both studies by force feeding at 7% of metabolic body weight (MWT; body weight.66) daily. In Experiment 1, using broilers not acclimated to heat stress, nicarbazin increased H (P < .05) (9.5 vs. 9.0 kcal/h per MWT) and body temperature (P = .08), reduced (P < .05) respiration rate, and had no impact on E or S (P > .1). In contrast, the bird acclimated to heat stress used in Experiment 2 exhibited similar (P > .1) thermobalance responses irrespective of nicarbazin supplementation. The data suggests that heat-stress-mediated nicarbazin toxicity may be related to H and further that nicarbazin's heat-stress-mediated toxicity is reduced in HS-acclimated chicks.