1. The effects of high calcium intakes on the pH and availability of calcium, iron, magnesium and zinc in the gastrointestinal tract (GIT) contents of meat chickens were studied in two experiments. 2. A high dietary concentration of calcium (25.3 vs 10.7 g/kg) increased the pH of crop and ileum contents, but did not influence the pH of the contents of other segments of the GIT. 3. The solubilities of minerals in GIT contents were reduced and the size of dissolved mineral complexes were increased as the digesta moved from the duodenum and jejunum to the ileum. 4. After feeding diets with calcium and available phosphorus concentrations (15.3 and 4.3 g vs 21.8 and 4.3 g vs 22.6 and 8.3 g/kg), centrifugation of GIT contents showed that most (70-92%) of the calcium, iron, magnesium and zinc was in an insoluble form. High calcium diets reduced the proportion of soluble zinc associated with small complexes, and high calcium and available phosphorus diets reduced the proportions of soluble magnesium and zinc associated with small complexes. 5. These findings explain the mechanism of the reduced availability of zinc and magnesium in high calcium and high available phosphorus diets.

The effects of dark-control (D) and continuous green light (GL) exposure of incubated meat-type breeder eggs (Hybro) on embryonic growth from 5 to 15 days of age, hatching time, hatchability per cent and chick hatching weight were investigated in three consecutive experiments at 33, 38, and 41 weeks of age. A total of 798 eggs were used in this study. Eggs were set in an incubator on trays either in the D or under two tubes of 20-watt green fluorescent light during the first 18 days of incubation. Eggs from both treatments were transferred to the dark hatching compartment at 19 days of incubation. The light intensity was in the range of 1,340 to 1,730 lux at the surface of the eggs. GL incubation of eggs significantly (p<0.01) increased weight (expressed as an absolute value) and daily weight gain of embryos at 11 and continued to 15 days of age, hatchability per cent by 4.8%, reduced dead embryos per cent and chick weight at hatch by 37 and 2%, respectively and accelerated hatching time by about 24 h when compared with the D-control incubation. Chicks hatched at 504 h of incubation had significantly (p<0.01) higher body weight, expressed as an absolute value or as a percentage of egg weight, than those hatched earlier at 456 h of incubation. It was concluded that the GL incubation of meat breeder eggs reduced incubation period and chick weight at hatch and increased embryonic growth and hatchability per cent.

1. The effects of different dietary concentrations of calcium (Ca), available phosphorus (AP) and vitamin D (D) on 5- to 16-day growth performance, and aspects of calcium and phosphorus (P) metabolism of chickens from three commercial strains were studied in two experiments. 2. Increasing dietary Ca reduced weight gain, tibia Ca and P content and increased plasma total Ca, Ca consumption and excretion, whilst dietary Ca at 32 g/kg increased tibia Ca:P ratio, plasma ionized calcium and reduced plasma P, tibia ash, P excretion, excreta moisture and Ca retention. 3. Increasing dietary AP reduced plasma total and ionized Ca and excreta moisture and increased P consumption and excretion, plasma P and tibia ash. 4. The addition of vitamin D increased plasma total and ionized Ca, tibia Ca:P ratio and reduced plasma sodium and P concentrations. 5. Strains differed in their tibia contents of Ca and Ca:P ratios, in response to Ca, AP and vitamin D diets whilst they differed in Ca excretion and excreta moisture caused by feeding either dietary Ca or AP. 6. It was concluded that dietary Ca, AP, vitamin D and strain of broiler chickens influenced the metabolism of Ca and P and that, as a consequence, the tolerance to high dietary Ca. A lean strain of chickens tolerated high dietary calcium better than its fat counterparts.

-Forty Najdi ram lambs weighing 26.6±0.3 kg were utilized in this experiment to determine the effects of feed restriction followed by realimentation and body weight at the onset of feed restriction (30 and 36 kg body weights) on performance and carcass characteristics; feeding and restriction levels were ad libitum, 0.75 and 0.60 of the ad libitum intake. All lambs were slaughtered after 14 weeks of experimentation. The results showed that, during the feed restriction phase, average daily gain (ADG) and feed efficiency decreased as the level of restriction increased. During the realimentation phase, the 30 kg lambs gained weights and consumed dry matter (DM) similarly to the ad libitum group, whereas the ADG for the 36 kg lambs of both 0.75 and 0.60 ad libitum groups were 20 and 43.8% faster than the ad libitum group, respectively. At the end of the trial, final body weight and overall ADG of the realimented 30 kg groups were lower than ad libitum group, whereas the ADG of the 36 kg groups were not different compared with the ad libitum group. Although empty body, hot and cold carcass, empty stomach compartments, empty intestines and liver weights for the 36 kg groups were not affected by feed restriction followed by realimentation, weights of visceral fat depots, subcutaneous fat and tail fat decreased much more than those of the ad libitum group. Carcass composition of the realimented 0.75 and 0.60 ad libitum groups tended to have 5.1 and 8.8% less lean tissue than the ad libitum group when the restriction started at 30 kg, respectively. On the other hand, the realimented lambs of both 0.75 and 0.60 ad libitum groups tended to be 5.1 and 2.8% leaner than those of the ad libitum group when restriction started at 36 kg body weight, respectively. Feed restriction of up to 40% for a 5-week period followed by a 4-week period of refeeding in 36 kg lambs is economically feasible and does not offset production.

The effects of in ovo amino acid administration on hatchability traits and post-hatch performance were studied using eggs from a meat-type breeder flock (Ross) at 38 weeks of age. On day 15 of incubation, five treatments were applied, consisting of six replicates with 16 eggs per replicate. The treatments consisted of a non-injected negative control; a positive control in which saline was injected; and three treatments with saline, containing 23.72 mg lysine, glutamine, glycine and proline (AA1); 23.60 mg arginine, glutamine, glycine and proline (AA2); and 28.76 mg lysine, arginine, glutamine, glycine and proline (AA3). The hatchability traits were incubation period, chick weight at hatch as an absolute value (CWT) and chick weight at hatch as a percentage of egg weight (CWTP), and the post-hatch performance traits were body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). Measurements on the chickens were taken during the starter (1 -21 days of age), finisher (22 -35 days of age) and entire (1 -35 days of age) experimental periods. In ovo amino acid treatments improved CWTP without affecting hatchability traits, and increased FI without altering the FCR of chickens during the entire experimental period. Chickens of the in ovo AA1 treatment had a higher FI than those of the control treatments during the finisher period. In ovo AA2 treatment increased CWT and BWG of the chickens during the starter period and entire experimental period and FI during the finisher period, when compared with those of the control treatments. In ovo AA2 treatment resulted in a longer period of incubation than those of other treatments. It was concluded that in ovo amino acid treatment increased CWTP and FI of chickens without affecting hatchability traits and feed efficiency and in ovo of AA2 treatment increased the incubation period, CWT and BWG when compared with those of control treatments during the entire experimental period. ______________________________________________________________________________________

________________________________________________________________________________ AbstractEggs from a meat-type breeder flock at 29 and 35 weeks of age were used in two trials to investigate the effects of in ovo feeding of carbohydrates (CHO) and high incubation temperature (37.5 vs. 38.5 °C (HIT)) during days 16 to 21 of incubation on hatchability traits, chick weight at hatch as an absolute value or as a percentage of egg weight (CWTP), hatching time, glycogen concentration in the liver and pectoral muscle, and glycogen index of hatched chicks. The treatments were a non-injected control, a positive control where saline was injected, or saline with a CHO mixture at 50, 100, 150, 200 and 250 mg/egg. The CHO mixture was maltose, sucrose and dextrin in a proportion of 1 : 1 : 8 by weight. As a result of this study, in ovo feeding of CHO increased CWTP without altering hatchability traits. Hatched chicks from eggs injected with 250 mg CHO/egg had a higher liver glycogen content and glycogen index than those of the control treatments. The high incubation temperature reduced chick weight, hatching time, liver glycogen and glycogen index of the hatched chicks. In ovo feeding of 100 and above mg CHO/egg overcame the negative effects of HIT. Hatched chicks from older hens had a lower concentration of liver glycogen and glycogen index than those of younger hens. It was concluded that in ovo feeding of CHO improved the weight and glycogen index of hatched chicks and those of the HIT treatment, and older hens negatively affected the glycogen index of hatched chicks. ________________________________________________________________________________

Eggs obtained from 46 and 42 weeks old meat (Hybro) and layer (Leghorn) breeders flocks, respectively were used to examine the effects of genetic type of birds and egg size (small, medium and large) on variables of eggshell characteristics and hatchability traits. The variables measured were egg weight (EW), egg surface area (ESA) and eggshell characteristics (shell conductance (EC), per cent shell (PS), shell thickness (ST), shell volume (SV), shell density (SD) and hatchability traits (per cent hatchability (HP), early dead embryos (ED), late dead embryos (LD), pips with live embryos (PL) and pips with dead embryos (PD)). Genetic type of bird influenced all egg characteristics and HP of eggs. Eggs produced by the small Leghorn bird had lower EW, ESA, EC, ST, SV and HP than those produced by the heavy Hybro bird. The reduction of HP was associated with an increase in the percentage of ED and PL. Egg size influenced all variables measured except ST. Small size eggs had lower EW, ESA and EC and higher PS and SD than those of large eggs. Medium size eggs produced a higher HP when compared with that of large size eggs. The reduction of HP in large eggs was associated with higher percentage of ED, LD and PL. There were significant interactions between the genetic group of birds and egg size on LD and HP. Large egg size of Hybro birds had higher LD and lower HP than those of small size eggs produced by the same flock. However, There was no difference in HP and LD among the different egg sizes produced by Leghorn birds. It was concluded that genetic make up of birds and egg size influence eggshell characteristics and HP. The type of bird (heavy or small) influences the optimum egg size for successful hatching. Attention should be given to the size and eggshell characteristics of eggs of breeders' flocks for achieving maximum HP.

Excess calcium intake has been shown to reduce growth and feed efficiency and to increase bone ash and bone strength in growing chickens. Source and level of dietary phosphorus have been shown to affect calcium tolerance. The effects of high calcium can be largely explained by its effects on intestinal pH. The proposed mechanism involves excess calcium reducing the soluble fraction of minerals and the proportion of minerals in small complexes. In consequence, their availability for absorption is probably also reduced. The growth depression of chickens fed on diets high in calcium may be partly caused by the decreased availability of other minerals needed for growth. Calcium tolerance of growing chickens may be increased by ensuring that there are higher than normal levels of the other required minerals in the diet. A comparison of phosphorus assay techniques with chicks. 8. Evaluation of two dietary levels of plant phosphorus for use in phosphorus assays. Poultry Science 50: 596-601 CLIFCORN, L.E., ELVEHJEM, C.A. and HART, E.B. (1938) The development of a ration for the study of perosis in chicks.