Performance and physiological responses of broiler chickens to supplemental guanidinoacetic acid in arginine-deficient diets.

1. The present experiment was designed to examine arginine (Arg)-sparing effects of guanidinoacetic acid (GAA) on production performance, intestinal morphology and certain blood parameters in broiler chickens. 2. A total of 300 male broiler chicks (Ross 308) were randomly allotted to 5 dietary treatments in a completely randomised design during 1-15 and 15-35 d rearing periods. Experimental treatments consisted of a basal diet with a reduction in Arg content (CON-; starter: 12.1 g/kg and grower: 11.3 g/kg Arg), a CON- diet supplemented with synthetic Arg equal to the required Arg level (CON+; starter: 13.80 g/kg; grower: 12.37 g/kg) and CON- diet supplemented with three levels of GAA (GAA0.6; GAA1.2; and GAA1.8; g/kg). 3. Supplemental GAA at 0.6 and 1.2 g/kg reduced the adverse effects of the CON- diet on weight gain and feed conversion ratio in the starter period, equal to the effect of CON+ diet. During the entire rearing period, such an effect was only seen for broilers fed CON- diet supplemented with 1.2 and 1.8 g/kg GAA (P < 0.05). Proportional weights of liver and abdominal fat were decreased in birds fed diets containing supplemental Arg and 1.8 g/kg GAA compared to the CON- broilers (P < 0.05). Jejunal villus height and villus height to crypt depth ratio were increased in broilers receiving the CON- diet (P < 0.05). Serum concentration of nitric oxide increased when the CON- diet was supplemented with either Arg or 1.8 g/kg GAA (P < 0.05). 4. Dietary inclusion of GAA had an Arg-sparing effect, whereby 1.2 and 1.8 g/kg of supplemental GAA resulted in greater growth performance during the starter and entire rearing periods, respectively. Supplementation with 1.8 g/kg GAA had significant effects on some carcass and physiological parameters.

Broiler chicks with slow-feathering (K) or rapid-feathering (k+) genes: Effects of environmental stressors on physiological adaptive indicators up to 56 h posthatch.

Two experiments were conducted to examine the effects on the physiological responses of slow-feathering (K) and rapid-feathering (k(+)) genes in neonate broiler chicks subjected to posthatch fasting (PHF). In the first experiment, 300 Ross 308 chicks were denied access to feed and water for 0, 7, 14, 21, 28, 35, 42, 49, and 56 h posthatch. In the second experiment, 625 Ross 308 chicks were subjected to PHF for 0, 12, 24, 36, and 48 h. In experiment 1, the weight loss rate increased over 56 h PHF and did not differ between fast- and slow-feathering chicks up to 28 h posthatch but was greater (P < 0.05) in fast-feathering birds from 28 to 56 h posthatch. The fast-feathering genotypes demonstrated greater serum K levels following 7, 21, and 56 h (P < 0.05) and serum uric acid (UA) levels after 7, 21, 28, 49, and 56 h PHF (P < 0.01). In experiment 2, weight loss increased linearly with no difference between fast- and slow-feathering chicks through 36 h PHF but increased in fast-feathering birds when PHF continued for 48 h. Neonatal fasting periods of 12 to 48 h decreased breast and thigh percentage (P < 0.01), with no difference between feathering genotypes. The fast-feathering genotypes showed greater serum HDL levels at 24 h (P < 0.05) and greater serum UA concentration following 12, 36, and 48 h PHF (P < 0.05). The mean frequency of jumping (P < 0.01) and active wakefulness (P > 0.01) was increased as PHF continued from 12 to 48 h across genotypes. At 48 h, the fast-feathering chicks showed greater frequency of escape attempts from the test field (P < 0.01). It was concluded that slow-feathering chicks are more capable of withstanding PHF periods lasting more than 28 h. This is important to consider when day-old chicks are transported for extended periods without access to feed.

Physiological adaptive indicators in fasted neonate broiler chicks in response to calcium gluconate injection.

Four hundred and eighty mixed-sex broiler chicks aged 3 h after hatching were allotted according to a completely random design in a 6 × 2 × 2 factorial schedule into two groups of 12 replications of 20 chicks each. The main experimental factors were fasting for 0, 6, 12, 24, 36 and 48 h after chick placement and calcium gluconate (Ca-glu) injection (0 and 0.6 ml). Live body weight (BW) of chicks decreased linearly (Y = 43.36-0.109BW0 h , r(2)  = 0.876) as neonatal fasting extended. Injection of 0.6 ml Ca-glu at 3 h post-hatching did not affect weight loss of chicks. Yolk residuals (YR) utilized linearly (Y = 5.75-0.062YR, r(2)  = 0.956) by 0.062 g/h in neonate fasted chicks up to 48 h, showing no effect of Ca-glu injection. Neonatal fasting periods longer than 12 h increased liver weight (p < 0.05). The mean absolute and proportional (% of BW0 h ) breast and leg weight were reduced linearly as neonatal fasting extended (p < 0.05). Serum glucose concentration increased up to 6 h and then reduced linearly to 150 mg/dl after 48-h fasting. The Ca-glu treatment influenced serum glucose level for a short period up to 6 h of fasting. Serum Ca concentration sharply increased up to threefolds in the birds received Ca-glu injection resulting in acute hypercalcemia, then decreased to the initial level after 24-h feed withdrawal (p < 0.05). The mean serum level for creatinine, uric acid, cholesterol, HDL, albumins and total proteins significantly increased during the fasting periods of 6 to 48 h and significantly elevated in the birds receiving 0.6-ml Ca-glu injection compared with the non-treated chicks (p < 0.05). It was concluded that subcutaneous administration of 0.6 ml Ca-glu in the chick's neck did not suitably support the increased metabolic demands for glucose and calcium in feed-deprived neonate chicks.

Effects of Satureja khuzistanica essential oils in drinking water on mortality, production performance, water intake, and organ weights in broiler chickens reared under heat stress condition.

An experiment was conducted to examine the effects on mortality, production performance, water intake (WI), and organ weight of Satureja khuzistanica essential oil (SkEO) using 720 1-day-old Arian broiler chicks in a 42-day trial. Experimental treatments were addition of 0 (control(-)), 200, 300, 400, and 500 mg/L SkEO or 500 mg/L polysorbate 80 (control(+)) into drinking water. The birds were kept under natural ambient temperatures 4 to 6 °C above standard recommendation from days 22 to 42 of age. Addition of SkEO into drinking water at 200 and 500 mg/L decreased weight gain (P < 0.05) of the birds from days 29 to 35 of age with no differences in feed intake (FI) and feed conversion ratio (FCR) compared to control groups (P > 0.05). Supplementation of drinking water with 200, 300, 400, and 500 mg/L SkEO resulted in a 0.47, 4.40, 8.60, and 12.93% decrease in WI, respectively, from days 1 to 42 of age. The calculated European broiler index was greater for the birds received 400 mg/L of SkEO in their drinking water compared with that of the other birds (P < 0.05). Pancreas percentage was increased for the birds received 200 to 500 mg/L SkEO at days 21 and 42 of age compared with that of the control(-) birds (P < 0.05). The gall bladder weight was 17.56, 40.50, 12.16, and 38.73% greater for the birds received 200, 300, 400, and 500 mg/L SkEO compared with that of the control(-) birds, respectively. The results showed that an addition of 400 mg/L SkEO into drinking water for heat-stressed broiler chickens improves economic efficiency possibly by promoting digestion process, creating miniscule improvement in FCR and lowered mortality rate.

Effect of the slow (K) or rapid (k+) feathering gene on carcass related traits of broiler chickens selected for breast and thighs weight.

This study was undertaken to evaluate the impact of slow/rapid feathering sex linked gene on carcass weight (CW) and yield (CY) as well as carcass main parts in an experimental colored broiler flock employing to evaluate the response to selection for breast and thighs weight with imposing restriction against low value portions of carcass over three generations. Random samples of the birds were slaughtered to evaluate the carcass traits at 42 days of age. Cut up yield was determined by partitioning each carcass to breast, thighs as high value parts and wings, neck, rack and saddle as low value portions (LVP). Live body weight (BW; 42d) and legs yield (LY) as a proportion of carcass weight (as %CW) were significantly greater for k+k+/k+W genotypes compared to K-/KW bearing birds (P<0.05). Inter sex t-test comparisons revealed significant superioty of k+k+ genotype over K- in male birds for LY (as %CW) and LY (as %BW) (P < 0.05). Inter family analysis for 8 larger half sib families revealed infrequent superiority of K-/KW bearing birds over their sibs with the alternate genotype for breast yield (BrY; as %CW), legs weight (LW) and LY (as %CW) in two families. Inter family and inter females analysis for 7 larger half sib families showed highly significant superiority for k+W birds in LW (as %CW), BW and LVW in two families (P<0.01). Considering feathering rate as a fixed effect (KW vs. k+W) to analyze the females data revealed significantly greater means for fast feathered females (k+W) for BW, CW, breast weight, LW and LVW than the alternate genotype (P<0.05). It is concluded that in the today's straight-run broiler flocks with numerous influencing factors of margin effects, and with increasing demands for uniformity of carcass market where sexable day-old chicks are not of interest, to launch the fast feathering gene (k+) could be of positive economic consequences in broiler production.