An experiment was conducted to determine the effect of selection for growth (BW) on the onset of reproduction (first egg) in Japanese quail hens from growth-selected (HW) and randombred (R1) lines. The HW line had undergone over 40 generations of selection for increased 4-wk BW and was originally developed from the R1 line. Data were collected over two consecutive hatches and summarized by hatch and within lines. Body weight at 35 d of age was positively correlated with BW at sexual maturity (first egg) in both the R1 and HW lines, but these correlations were not significant in both hatches for either line (Hatch 1-R1; Hatch 2-HW; P < or = 0.05). There was a negative correlation between age at sexual maturity (days to first egg) and 35 d BW in both lines with the exception of the HW hens in Hatch 2. Age at sexual maturity and BW at sexual maturity was positively correlated (P < or = 0.001) in the R1 line but did not show the same relationship in the HW line. Age at sexual maturity and weight of the abdominal fat pad were positively correlated in the R1 line (Hatch 1, P < or = 0.01; Hatch 2, P < or = 0.001), but this relationship was not significant in the HW line. Age at sexual maturity and follicle number was negatively correlated in both lines but was not significant in Hatch 2 of the HW line. Follicle size, however, was positively correlated with days to first egg in only Hatch 2 (P < or = 0.001) of the HW line. The data suggest that the relationships between the onset of sexual maturity and both reproductive parameters and carcass traits in hens from consecutive hatches of HW quail are less clear than in the R1 line.

Three experiments were conducted with turkey poults to determine the effects of diet and delayed placement on growth and selected aspects of carbohydrate metabolism. Immediately after hatch, poults were placed in batteries and allowed either immediate access to feed and water (FED) or feed and water withdrawal for 48 h (WH). In the first two experiments, diets contained a high proportion of carbohydrate from corn (CHO; 60% of diet) or a lower proportion of corn (26%) and 10% supplemental animal-vegetable fat (FAT). The WH poults weighed less than FED poults at 5 d postfeeding (DPF; P < or = 0.05) but not at 13 DPF. Similarly, poults fed the CHO diet were heavier 5 DPF, whereas poults fed the FAT diet were heavier at 13 DPF (P < or = 0.05). Regardless of feeding regimen (WH vs FED), all poults were nearly depleted of hepatic glycogen prior to feeding. At 2 DPF, poults fed the CHO diet had more hepatic glycogen concentrations compared with those fed the FAT diet (P < or = 0.002). In addition, one-half of the WH poults fed the CHO diet had plasma glucose concentrations in excess of 500 mg/dL at 2 DPF. In Experiment 3, similar feeding regimens and diets were used with the addition of a third diet containing a synthetic medium-chain triglyceride emulsion (MCT) as the supplemental fat source. Poults fed the FAT and MCT diets were 41 g heavier than poults fed the CHO diet at 13 DPF (P < or = 0.05). Similar to the results of Experiment 2, poults fed the CHO diet had increased hepatic glycogen concentrations at 2 DPF, and within the WH treatment at 2 DPF, 30% of the poults had plasma glucose concentrations in excess of 500 mg/dL. Metabolic consequences of delayed placement were also found. At both 4 and 7 DPF, WH poults had a reduced capacity for glucose clearance 60 min after a glucose load (250 mg; P < or = 0.05). The current experiments demonstrate that supplemental fat may ease the metabolic shift toward glycolysis after hatching, thereby improving growth through 2 wk of age.

Turkey (Meleagridis gallopavo) liver cytosolic fatty acid binding protein (FABP) was purified and used as a standard for quantification. An immunoblotting procedure was developed to study the ontogeny of liver cytosolic FABP during embryonic and early posthatch development in turkey poults. Liver FABP activity was also determined indirectly through the use of gel filtration chromatography followed by a ligand-binding assay. The specific activity of liver FABP (ng/mg of cytosolic protein) increased with length of incubation, peaking initially at Day 22, declining between Days 22 and 25, and increasing again from hatch (Day 28) to 6 d posthatch. The specific activity of liver FABP increased 12-fold between Day 13 of incubation and 6 d posthatch compared with total activity, which increased from 946 to 1.01 x 10(6) ng/liver during the same period, a 1,067-fold increase. The results from both analytical procedures were similar, suggesting that the immunoblot method could be used to quantify liver FABP concentrations. The observed increases in FABP activity throughout the embryonic period and first days after hatching paralleled increases in liver lipid concentration. Therefore, liver FABP may be associated with hepatocyte fatty acid transport and metabolism during the latter stages of incubation and early posthatch period.

An experiment was conducted with turkey poults to determine the apparent digestibility and derivation of ME from diets containing a high proportion of carbohydrate from corn (CHO; 60% of diet) or 10%) supplemental fat from an animal-vegetable blended fat (FAT) or a synthetic medium-chain triglyceride (MCT). Poults fed the FAT diet consumed more feed from 6 to 8 and 9 to 11 d of age than poults fed the CHO diet, intake of the MCT diet was intermediate. From 3 to 11 d of age, the percentage apparent digestibility of nonlipid DM by poults fed the CHO diet was greater than that observed for either the FAT or MCT diets (P < or = 0.05). The percentage apparent digestibility of lipid was consistently greater for poults fed the MCT diet (> or = 90%) and could be attributed to the high apparent digestibility of C8:0 (>95%), which accounted for 76% of total MCT dietary fatty acids. Over the course of the experiment, the mean percentage apparent digestibility of lipid in the CHO and FAT diets was 76.4 and 70.8%, respectively, and did not change with increasing age. The lower percentage apparent digestibility of lipid in the CHO and FAT diets was attributed to the low apparent digestibility of C16:0 (70.4, 52.7%) and C18:0 (58.4, 26.8%), respectively. The apparent digestibility of the polyunsaturated fatty acids, C18:2 (n-6) and C18:3 (n-3), was consistently high and ranged from 72 to 85% and 81 to 88%, respectively. The CHO diet resulted in an approximate 6% increase in determined AMEn compared with either the FAT or MCT diets. The results of this study showed that commercial feed-grade fats are poorly digested by very young poults. The digestibility of polyunsaturated fatty acids, however, was shown to be quite high, and the data suggest that vegetable oils containing high proportions of polyunsaturated fatty acids or alternative fat sources containing high proportions of medium-chain fatty acids could be well utilized by the very young poult.

Sex-linked dwarf male (dw/dw) and female (dw/-) chickens from a commercial meat strain, grew significantly slower than genetically normal broilers (Dw/Dw). The differences were evident at 2 weeks of age and they remained constant with age, at least through 8 weeks. The dwarfs in turn grew significantly faster than genetically normal (Dw/Dw) but slow-growing roaster strain chicks. Heterozygous (Dw/dw) normal, fast-growing male broilers grew significantly faster than the normal and roaster chicks but weighed 8% less than the normal broilers at 8 weeks. Abdominal fat accretion was greatest in the dwarf chicks and least in the slow-growing roaster strain when comparisons were made at the same age and the same body weight. Pectoralis muscle growth was greater in the broiler strain when equal age and weight comparisons were made.Gastrocnemius muscle growth, however, was greatest in the slow-growing roaster chicks. o 1986