[Show abstract][Hide abstract]ABSTRACT: In vitro rates of O2 consumption were investigated using excised biopsies from the liver, ileum, magnum, and latissimus dorsi muscle of Hubbard (H) broiler-breeder hens fed four levels of ME intake. Diet had no effect on O2 consumption of any tissue. The overall mean initial O2 consumption (microL of O2 per mg of dry weight per h) for latissimus dorsi, liver, ileum, and magnum tissues were 4.38, 13.33, 10.54, and 8.01, respectively. The Na+ and K(+)-adenosine triphosphatase-dependent respiration (ouabain-sensitive respiration) was 16% of the initial rate for latissimus dorsi, liver, and magnum tissues and 22% for ileum tissues. Fasting heat production of H and Arbor Acre (AA) meat-type hens measured over 3 days following an initial 24-h fast was 219 and 216 kilojoules (kJ) per kg per day (1 kJ = .239 kcal). There were no strain differences in the partitioning of O2 consumption into tissue components of fasted H and AA hens. Fasting metabolism accounted for 75% of the maintenance energy requirement in the hens. The liver, gut, and reproductive tract, which together make up 5 to 6% of BW, account for 26 and 30% of the total energy expenditure in fed and fasted hens, respectively.
[Show abstract][Hide abstract]ABSTRACT: The partitioning of AME intake (MEI) and recovered energy (RE; defined as MEI minus heat production) was investigated on Hubbard
broiler-breeder hens (BB) by using indirect calorimetry and energy balance. The regression of RE on MEI was linear (R2 = .96; P<.01) with a slope of .817 ± .024 (SE) and a y-intercept of −238.3 ± 10.7 (SE). The maintenance energy requirement
was 292 kilojoule (kJ) per kg per day (367 kJ per kg.75 per day). The regression of body RE, defined as RE minus egg energy, on MEI was linear (R2 = .96; P<.01) with a slope of .799 ± .045 (SE) and a y-intercept of −344.9 ± 19.7 (SE). Therefore, an MEI of 432 kJ per kg
per day was required by BB hens to maintain body energy equilibrium when they were laying at approximately 85% production.
At an MEI of less than 432 kJ per kg per day, body energy was used for egg production. The AME cost of depositing 1 kJ of
body, egg, protein, or fat energy was (x̄ ± SE) 1.21 ± .06, .91 ± .32, 1.96 ± .71, and 1.05 ± .15 kJ, respectively. The results
indicate that individually caged BB hens between 28 and 36 wk of age in a thermal-neutral environment (21 C) require approximately
1.6 megajoule (MJ) of AME per bird per day for normal growth (3 g/per day) and egg production (85%).
[Show abstract][Hide abstract]ABSTRACT: Two hundred and forty individually caged Hubbard x Hubbard broiler breeders (BB) were fed one of six diets at 150 g/bird per day, which provided 19 or 25 g protein and 325, 385, or 450 kcal nitrogen-corrected metabolizable energy. In Trial 1, chicks hatched from 29-wk-old BB were sexed and 12 females and 12 males placed in each of four replicate floor pens per treatment. A 23% crude protein (CP) starter (0 to 20 day), 20% CP grower (21 to 34 day) and 18% CP finisher (35 to 41 day) diets were fed. Protein intake of BB had no effect on body weight of offspring. Energy intake of BB had no effect on growth of female offspring; however body weights of 20 day-old-male offspring were 575, 586, and 601 g for low, medium, and high energy intake, respectively (P less than or equal to .01). Increasing BB energy intake increased carcass protein and reduced fat in male offspring (P less than or equal to .01) and decreased the percentage of Canada Grade B ratings for both sexes (P less than or equal to .05). In Trials 2 to 4, chicks from BB at 32, 36, and 40 wk were sexed and cage-reared to 21 days of age. The energy intake of BB had no effect on female offspring growth. Male offspring weighed 570, 563, and 585 g for the low, medium, and high energy intakes, respectively (P less than or equal to .01).
[Show abstract][Hide abstract]ABSTRACT: Two hundred and forty Hubbard X Hubbard broiler breeders at 19 weeks of age were weight-sorted and transferred to individual laying cages where one of six experimental diets was provided to 41 weeks of age. Each diet was represented by 10 replicate groups of 4 individually caged and fed birds. Feed allocation was gradually increased to 150 g/bird per day, which provided 19 or 25 g crude protein and either 325, 385, or 450 kcal metabolizable energy (ME)/bird per day. Hens were inseminated every 7 days with .05 ml pooled semen from Hubbard males. Hen-day production was 1.6% lower with the high vs. low protein intake. Peak egg production occurred at 31 weeks and was 77.3, 87.9, and 84.1% for the low (L), medium (M), and high energy (H) intakes, respectively (P less than or equal to .01). Egg weight increased as the protein or energy intake increased; yolk content increased as energy intake increased or as broiler breeders aged (P less than or equal to .01). Carcass fat, protein, and moisture content of defeathered 41-week-old breeders were L: 45.5, 44.4, 56.6; M: 49.0, 40.4, 54.8; and H: 58.4, 32.5, 50.4, respectively (P less than or equal to .01). There were no dietary effects on hatchability, embryonic mortality, or fertility. From 32 to 35 weeks of age the higher protein intake increased egg weight by 1.2 g (P less than or equal to .05) and chick weight by .6 g; whereas hatched live chick weight was 39.6, 39.7, and 41.0, for L, M, and H diets, respectively (P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)
[Show abstract][Hide abstract]ABSTRACT: Single Comb White Leghorns (SCWL), regular broiler breeders (BB), and dwarf BB between 45 and 52 weeks of age were used to investigate the effect of strain on nitrogen-corrected metabolizable energy (MEn) of various diets. Data are reported on a 90% dry matter basis. In Trial 1, a 20.0% crude protein diet had MEn of 2,736 kcal/kg determined with regular BB, significantly less than 2,805 determined with SCWL (P less than or equal to .05). The MEn determined with dwarf BB was 2,778 kcal/kg. Similar strain differences occurred with 14.3% crude protein diet calculated to be isocaloric using NAS (NRC) 1977 feed composition tables. In Trial 2, MEn of a high energy diet was 2,906 kcal/kg determined with regular BB, less than dwarf BB or SCWL which were 2,947 and 2,976 respectively (P less than or equal to .01). In Trial 3, ad libitum vs. 75% feed restriction had no effect on MEn determined with regular BB (P greater than .05). These results indicate that regular BB hens derive less metabolizable energy from the diet than do SCWL birds.