Effects of cold stress on physiologic metabolism in the initial phase and performance of broiler rearing.

This study aimed to investigate the effects of 8 h of cold stress (18 °C) every day in broiler chicks during the first 7 days of rearing on crop filling analysis, yolk sac consumption, digestive and immune organs weights, and physiological metabolism at seven days and performance between 1 and 35 days. Cobb500 male broiler chickens (n = 274) were randomly assigned to two treatments. The treatments consisted of varying environmental temperatures during the first week post-housing. Chicks were reared at a thermoneutral temperature (32 °C) or under cold stress (18 °C) for 8 h/day during the first week, and both groups were subsequently reared at a thermoneutral temperature for 8-35 days. The thermoneutral group reached 90% full crop after 48 h of housing (P < 0.05), while the cold-stressed group had more empty crops at 2 h and 48 h after housing (P < 0.05). The chick cloacal temperature was not affected by the treatments (P > 0.05). Additionally, the treatment did not affect serum amylase and corticosterone levels, feed intake, body weight gain, or feed conversion ratio (P > 0.05, while the cold-stressed group had elevated heterophil/lymphocyte count at day 7 (P < 0.05). The thermoneutral group showed higher viability (%) at 7 and 35 days and a higher production factor at 35 days (P < 0.05). Broiler chickens under cyclic cold stress experienced decreased yolk sac absorption during the first week and increased feed intake and feed conversion ratio after 35 days of rearing. Viability was also lower in the cold-stressed group. An appropriate strategy to minimize these adverse effects is to rear the chicks in a thermoneutral environment during the first week.

Feed form and nutritional level for rearing growing broilers in thermoneutral or heat stress environments.

The present study aimed to investigate the effects of different physical forms of feed and feeding programs on nutrient digestibility and performance of grower-finisher broilers under thermoneutrality or thermal stress. Three experiments were conducted using male broiler chickens (n = 720) aged 19-42 d. The design of two of the experiments was fully randomized in a 2 × 2 factorial arrangement with two forms of feed (mash and pellet) and two nutritional levels (13.19 MJ/kg and 194.8 g/kg CP - normal level and 13.61 MJ/kg and 210.3 g/kg CP - high level). The experiments took place in a climate-controlled room: Experiment 1 at thermoneutrality (21-23 °C and 58-60% relative humidity) for 24 h/day; Experiment 2 under thermal stress cycle (31-32 °C and 63-65% relative humidity), for 6h/day and thermoneutrality (21-23 °C, 58-60% relative humidity) for 18h/day. The nutrient digestibility and performance was analyzed. The design of the third experiment was fully randomized with two ambient condition treatments (thermoneutral and thermal stress) on heat production, caloric increment and net energy. Pellet feed obtained higher digestibility of dry matter, digestibility of crude protein, AME and AMEn (P < 0.05) than mash feed for broilers reared in the thermoneutral environment. At the high nutritional level there was no effect of treatments on the coefficient of dry matter and crude protein (DCCP) (P > 0.05), while the highest digestibility of AME and AMEn were obtained by the high nutritional level diet (P < 0.05). Pellet feed had higher DCCP (P < 0.05) than mash feed for broilers reared under cyclic heat stress. Broiler chickens under cyclic stress experienced increased caloric increment, rectal temperature and respiratory rate. The appropriate strategy to minimize these effects in both ambient conditions is to pellet feed.

The transfer of amino acids and minerals to the egg yolk and to the yolk sac of their progeny is affected by breeder age.

This study aimed to assess the effects of breeder age on egg quality and amino acid and mineral transfer to the egg yolk and yolk sac of newly hatched chicks. Three ages (32, 42 and 52 weeks) of the same commercial flock of Hubbard breeders were studied. A total of 465 eggs were used for each age, with 60 being used for determining egg quality and amino acid and mineral content of yolk, and 405 for incubation period to obtain and evaluate the yolk sac of chicks. Breeders aged 52 weeks had heavier eggs and a higher percentage of yolk (p < 0.05), whereas 32-week-old breeders had higher eggshell percentage and thickness (p < 0.05). The percentage of protein deposited in egg yolk for 52-week-old breeders was higher than that for 32- and 42-week-old breeders (p < 0.05). Percentages of methionine, cysteine, met + cysteine, lysine, threonine, tryptophan, arginine and isoleucine in egg yolk for 32-week-old breeders were higher than that for 42- and 52-week-old breeders (p < 0.05). The transfer from breeder of phosphorus, potassium, calcium, magnesium, copper, iron, manganese and zinc to the yolk of eggs from 32-week-old breeders was greater than that for eggs from 42- and 52-week-old breeders (p < 0.05). Chicks from 32-week-old breeders had greater deposition of phosphorus and calcium in the yolk sac (p < 0.05). Breeder age did not affect the deposition of potassium, magnesium, copper, iron, manganese and zinc in the yolk sac of newly hatch chicks (p > 0.05). It can, however, be concluded that younger breeders deposit more amino acids and minerals in egg yolk, while embryos of older breeders seem to use the nutrients present in the yolk more efficiently during embryonic development.

Short communication: Effects of breeder age and pre-placement feed on IgY concentration in egg yolk and chick serum.

Breeder age and pre-placement feed are factors that can affect broiler performance during grow out. This study evaluated the effects of breeder age (29 and 55 weeks old) on IgY transference to egg yolk in addition to the effects of breeder age (29 and 55 weeks old) and pre-placement feed (with or without), in a factorial arrangement, on IgY concentration in chick serum. Forty-eight eggs were collected from a breeder flock and considered the experimental units. Eighteen chicks from each breeder age were randomly selected to determine IgY at pulling. After 48 h of placement, old breeders had greater egg weight and yolk weight (p ≤ 0.05) than the young ones. Breeder age (p > 0.05) had no effect on IgY concentration of egg yolk. Breeder age (p > 0.05) had no effect on IgY concentration of chick serum at pulling. There was no interaction (p > 0.05) between breeder age and pre-placement feed for IgY concentration of chick serum at housing. There was also no effect of breeder age or pre-placement feed during placement time (48 h) on IgY concentration of chick serum at housing (p > 0.05). In conclusion, 48 h of fasting had no effect on IgY concentration in chick serum despite breeder age. It appears that the immunoglobulins from the residual yolk sac are not used as a protein source during the period between hatching and housing.

Prevalence, antimicrobial resistance and detection of virulence genes of Escherichia coli and Salmonella spp. isolated from white-lipped peccaries and collared peccaries.

Salmonella spp. and Escherichia coli are implicated in human and animal infections and require antimicrobial treatment in many situations. Faecal samples of healthy white-lipped peccaries (Pecari tajacu) (n = 30) and collared peccaries (Tayassu pecari ) (n = 60) obtained in three farms located in the Midwest Brazil. The antimicrobial profiles of commensal E. coli from P. tajacu and T. pecari from commercial herds in Brazil were isolated and analyzed and virulence genes were detected. Among 90 healthy animals, no Salmonella spp. were isolated. However, 30 samples (27%) tested positive for E. coli, with 18 isolates from P. tajacu and 12 from T. pecari, representing frequencies of 58.0% and 38.7%, respectively. Additionally, other Enterobacteriaceae family bacteria were detected but not included in this analysis. However, individual samples from 30 animals tested positive for E. coli, of which 16 were isolated from P. tajacu presenting multidrug resistance and six were isolated from T. pecari presenting a similar pattern. The E. coli virulence genes detected were papC (pilus-associated pyelonephritis) in five isolates, tsh (temperature-sensitive hemagglutinin) in one isolate, and eae (enteric attachment and effacement) in one isolate. The serum resistance gene, iss (increased serum survival), was detected in four isolates. An association between these genes and the presence of hemolysin was also observed in one isolate. Thus, T. pecari and P. tajacu are potential reservoirs of pathogenic and multidrug-resistant and E. coli. Faecal E. coli of healthy P. tajacu and T. pecari could act as a possible reservoir of antimicrobial resistance genes in environment.

Floor eggs: Hatchability, microbiological analysis, and effects of post-hatch use of ceftiofur on performance of broiler chicks.

The present study aimed to determine the effects of egg type (nest clean or floor eggs) on eggshell microbiological, hatching performance, chick quality, yolk sac microbiology, and the interaction between egg type and post-hatch use of ceftiofur on broiler performance at 7, 14, 21, 28 and 35 days. A total of 2500 fertile eggs were obtained from a commercial flock of Cobb Slow® broiler breeders. Half of the eggs were collected directly from the floor, and the other half were collected from the nests. Microbiological evaluation of eggshells was performed before and after sanitization. After hatching, 420 male chicks were randomly selected and distributed in a completely randomized design in a 2 × 2 factorial scheme, separated by the type of egg (clean nest or floor) and the inclusion or not of subcutaneous ceftiofur, totaling four treatments. Egg type did not influence hatchability although the contamination level was 1.3% higher. The body weight and body weight gain of chicks at seven days were greater for chicks from nest eggs that received ceftiofur than chicks from floor eggs that also received ceftiofur. There was no interaction between the studied factors or individual effects for performance at 14, 21, 28, and 35 days. It is concluded that incubation of floor eggs, after standard sanitization, does not influence the hatch results and chick quality. Furthermore, it has been proven that the use of ceftiofur is unnecessary when there is correct management during broiler rearing.