Biomedical subjects

S Leeson

Publications and source records attributed to S Leeson.

At least 91 records · Page 5Linked to original sources

PubMed1990

Body composition of the broiler-breeder pullet.

Broiler breeder pullets were reared on a standard breeder-grower diet in accordance with breeder recommendations to 10 wk of age, with samples of the birds being selected for carcass analysis at 2, 3, 4, 5, 6, 7, 8 and 10 wk of age. At 10 wk of age, 264 pullets were assigned to one of three diets formulated to contain 15% CP and to provide 2,550, 2,800 or 3,080 kcal of ME per kg. The birds on the 2,800-kcal diet were fed to attain the body weight recommended by the breeder; the birds on the other diets received the same feed allotment. At 14, 16, 18, 20, 22, and 24 wk of age, 12 birds per treatment were slaughtered for carcass analysis. All of the birds were light-stimulated at 20 wk of age. From 2 to 10 wk of age, carcass analysis of the feed-restricted pullets revealed a relatively constant protein content, 20 to 21%, accompanied by a declining proportion of fat. Feeding a high-energy diet from 10 to 24 wk of age increased body weight and the absolute and proportional content of fat. The percentage of body protein was largely unaffected by the diet, but there was a consistent effect on fat content (P less than .05). The body fat and protein contents were highly correlated with body weight.

Animals↗

PubMed1990

Energy metabolism of broiler breeder hens. 1. The partition of dietary energy intake.

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 less than .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 less than .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 (mean +/- 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%).

Animals↗

PubMed1990

Energy metabolism of broiler breeder hens. 2. Contribution of tissues to total heat production in fed and fasted hens.

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.

Animals↗

PubMed1990

Effects of feed restriction during the rearing period and age at photostimulation on the reproductive performance of turkey hens.

An experiment with Nicholas parent-stock turkey breeder hens was designed to determine the effects of feed restriction during the rearing period and age at photostimulation on reproductive performance. Hens reared on ad libitum intake of conventional corn-soybean diets (ad libitum), skip-1-day per week (skip-1-day), and 95% of ad libitum (95%) were placed into cages and photostimulated when they reached a target body weight of 10 kg or at the conventional age of 29 wk. A 3 x 2 factorial design was used, with five replicates of three hens for each treatment. All birds were fed for ad libitum access during the breeding period. More eggs were set from 95% birds than from ad libitum or skip-1-day birds (P less than .05); there was no difference between ad libitum and skip-1-day birds. Photostimulating based on 10 kg of BW versus 29 wk of age had no effect on total eggs set. There was no effect of rearing feed restriction on fertility or hatchability. Photostimulating based on 10 kg rather than 29 wk of age reduced fertility and hatchability (P less than .05). The results of this study indicate that optimum reproductive performance is attained by restricting the feed consumption of turkey breeder hens to 95% of ad libitum during the rearing period. No benefits were gained from photostimulating at 10 kg of BW versus 29 wk of age.

Age Factors↗

PubMed1990

Effect of feed restriction during the rearing period on the growth rate and carcass composition of turkey breeder hens.

An experiment with Nicholas parent-stock turkey breeder hens was designed to determine the effect of feed restriction on body weight and carcass composition. The following six feeding programs were compared using four replicate pens of 15 or 16 poults each: ad libitum intake of conventional corn and soybean diets (Ad), skip 1 day per week (S1), skip 2 days per week (S2), 95% of ad libitum (95%), 90% of ad libitum (90%), and 85% of ad libitum (85%). At 29 weeks of age, Ad birds were heavier than restricted birds (P less than .05); there were no differences among S1, S2, and 95% or between 90% and 85% treatments. The 95%, 90%, and 85% hens did not have as much carcass fat as did Ad hens (P less than .05); there were no differences among Ad, S1, and S2 treatments. The results of the present study show that feed restriction during the rearing period reduces the growth rate of turkey breeder hens. Quantitative feed restriction (95%, 90%, and 85%) appears to be the most effective method to reduce carcass fat content.

Animals↗

PubMed1989

Water usage of broiler breeders.

Water usage of daily fed and skip-a-day-fed broiler pullets housed in cages was measured in two trials. Daily fed birds in both trials had free access to water. In Trial 1, skip-a-day-fed birds were restricted to 4 h water every day or only on feed days. In Trial 2, the skip-a-day-fed birds were water restricted 4 h either every day, only on feed days, or had free access to water. Skip-a-day-fed birds tended to drink more water on feed days than on off-feed days but amounts were significantly different only in Trial 2. Water intake of these skip-a-day-fed birds on off-feed days was less than that of comparable birds fed on a daily basis with free access to water. Conversely, skip-a-day-fed birds drank more water on feed days than did daily fed birds (P less than .05) when both groups were given free access to water. Overall mean daily water consumption and spillage were unaffected by feeding or water restriction regimens. The main influence of skip-a-day feeding and water restriction appears to be on the pattern of water consumption and not on overall water usage. Daily feeding increased body weight gain relative to that of birds fed skip-a-day, although water restriction did not influence growth. Metabolizable energy derived from a feed was unaffected by feeding or water restriction regimens.

Animals↗

PubMed1989

Growth of broiler breeder pullets with skip-a-day versus daily feeding.

One hundred and sixty-eight broiler breeder pullets were fed skip-a-day or half the same feed allotment on a daily basis from 5 to 20 wk of age. When weighed on the same day, daily fed birds were significantly larger than skip-a-day-fed birds, but this difference appears to be partly due to feed retained in the digestive tract. Body composition and uniformity were unaffected by feeding regimen.

Animals↗

PubMed1988

A simplified diet for assaying methionine activity.

Several experiments were undertaken to evaluate diets that could be used to bioassay methionine activity in various compounds. The following semipurified diets were tested: a corn-soy-gelatin basal (CSG) diet supplemented with essential amino acids (EAA) at 23% crude protein (CP); a soybean meal diet at 23% CP; and a soybean meal diet at 15% CP with all the protein coming from dehulled soybean meal and starch, glucose, and fat used as sources of energy. The CSG and 15% CP soybean meal diets proved to be sensitive in their response to methionine supplementation. Birds fed the CSG diet supplemented with methionine and tryptophan were smaller (P less than .01) than birds fed the 23% CP soybean meal diet, thus suggesting that something other than EAA was limiting the performance of birds fed this diet. Based on sensitivity to methionine supplementation, simplicity and cost of diet, the low protein soybean meal diet seems most appropriate for methionine bioassays.

Animal Feed↗

PubMed1988

Significance of growing photoperiod and light stimulation at various ages for Leghorn pullets subjected to regular or ahemeral photoperiods.

Leghorn pullets were cage reared to 15 or 19 wk of age in environmentally controlled rooms that provided either 8 h or 14 h of light per day. In Experiment 1, birds were moved to laying cages at 15 wk of age and subjected to either 14 h light (L): 10 h (D) dark or ahemeral 14L:14D photoperiods. Feed intake, egg weight, shell quality, and egg production were monitored to 67 wk of age. In Experiment 2, pullets were moved at 19 wk of age and subjected to 14L:10D or 17L:7D light programs. Production parameters were measured as previously described. No significant (P greater than 0.5) interactions were observed between rearing and laying photoperiods, suggesting that increase in the length of photoperiod around time of maturity is not essential for adequate performance. In Experiment 1, ahemeral lighting resulting in reduced egg production, whereas egg shell quality and egg weight were improved (P less than .05). In both experiments, the 14-h rearing program resulted in improved egg size together with improved eggshell quality (P less than .05). Whereas increased egg size may relate to body weight, no explanation is apparent for the consistent pattern with respect to shell quality. In Experiment 2, poorer shell quality was observed with 17 vs. 14 h light per day. It is concluded that light stimulation at maturity has little effect on overall egg production. Improved shell quality observed with birds reared under 14 h light vs. those reared under 8 h per day may relate to a less rapid attainment of peak egg production.

Aging↗

PubMed1988

Effect of feed restriction on feed efficiency and incidence of sudden death syndrome in broiler chickens.

An experiment was conducted to determine the effect of feed restriction on the incidence of sudden death syndrome (SDS). Body weight, feed efficiency, and incidence of SDS were compared for broilers fed ad libitum and broilers restricted in feed intake by 25%. Six pens of 50 male broilers were fed commercial-type texture diets ad libitum, and six pens of birds were restricted to 75% of this intake from 5 to 39 days of age. Growth rate and the incidence of SDS were significantly higher in ad libitum-fed broilers. Feed efficiency was better in the ad libitum-fed group up to 11 days of age and then became similar to that of the restricted group. Results support the hypothesis that the incidence of SDS is related to growth rate and suggest that SDS mortality may be reduced by growing broilers at a slower rate.

Animal Nutritional Physiological Phenomena↗

PubMed1988

Restricted water access time as a means of growth control in turkey tom breeder candidates.

Seventeen-wk-old turkey tom breeder candidates were allowed access to water for 4 h each day, as 2 x 2-h periods, to 21 wk. After this time, water access was reduced to 1.5 h/day (21 to 25 wk) and subsequently to 1 h/day (25 to 33 wk). Access time was reduced over time, as the earlier water access time allocation was considered excessive. With 1-h access time each day (2 x 30 min) there were no behavioral signs of thirst, and toms did not use the total time allocation for drinking. Restricted access to water reduced body weight from 25 to 33 wk of age (P less than .05). This BW reduction was accompanied by a nonsignificant reduction in feed intake. At 35 wk of age, semen weight (P less than .05) and sperm count (P less than .01) was increased for toms previously subjected to restricted water-access time. It is concluded that restriction of time that toms are allowed to drink can be used to augment other methods used in control of body weight.

Animals↗

PubMed1987

Determination of metabolizable energy of various diets using Leghorn, dwarf, and regular broiler breeder hens.

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.

Animal Feed↗

PubMed1987

Broiler breeder performance in response to diet protein and energy.

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)

Animals↗

PubMed1987

Effects of increasing dietary levels of full-fat canola on performance, nutrient retention, and bone mineralization.

Day-old male broiler chickens were fed diets containing 0, 5, 10, 15, or 20% raw, ground, full-fat canola for a period of three weeks. Increasing the dietary proportion of full-fat canola significantly reduced feed intake (P less than .05) and weight gain (P less than .01), without altering feed:gain ratio. Diet had no significant effect on protein retention although there was a significant decrease in fat retention with an increase in dietary levels of full-fat canola (P less than .01). This was accompanied by a significant decrease in metabolizable energy (P less than .01). Increasing the proportion of dietary full-fat canola significantly reduced the concentration of soap in the digesta (P less than .05) and excreta (P less than .01). There was no significant effect of the dietary treatments on calcium or phosphorus retention. There was also no effect of the dietary full-fat canola on bone ash, bone calcium, or phosphorus content.

Animal Feed↗

PubMed1987

Effect of protein and energy intake of broiler breeder hens on performance of broiler chicken offspring.

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).

Animal Nutritional Physiological Phenomena↗

PubMed1987

Rearing early maturing pullets.

A number of experiments were undertaken using White Leghorn pullets to determine the effect of diet and growing treatment on 16-wk body weight and carcass composition. Irrespective of the level of dietary energy, body weight gain and carcass composition appeared to be closely correlated with energy intake of the pullets. Diets as low as 15% protein with and without methionine supplementation resulted in 16-wk body weights similar to those of animals fed diets containing 21% protein, suggesting that protein is not a critical nutrient influencing weight gain of pullets. Pullets fed ad libitum every other day from 12 to 16 wk of age were significantly lighter at 16 wk than pullets full fed a regular grower diet or the regular diet diluted with 20% oat hulls. Pullets must achieve a certain body weight and carcass composition in order to trigger the onset of production. Dietary energy, not protein, appears to be the critical nutrient involved.

Animals↗

PubMed1987

Assay for estimating the potency of various methionine-active sources.

A number of experiments were conducted to verify the sensitivity of a low protein (15%) soybean diet for assaying methionine (Met) activity. Although a good response in weight gain and feed:gain ratio was obtained with the addition of supplemental Met to the basal diet, an inconsistent response was obtained when the efficacies of DL-Met and liquid methionine hydroxy analogue (MHA were tested). The addition of nonessential amino acids produced a variable response when added to diets containing MHA, with no difference in the response to aspartic acid or a glycine/glutamic acid mix as nitrogen sources. The addition of glycine to diets supplemented with DL-Met resulted in improved performance with the highest level of Met supplementation, thus suggesting that glycine may be alleviating some deficiency in the high supplemental Met diet. Based on the results of several experiments, MHA was judged to be less efficient than DL-Met on a weight basis.

Animal Feed↗

PubMed1987

Effect of dietary calcium levels near the time of sexual maturity on water intake and excreta moisture content.

Three trials were conducted to investigate the effect of dietary calcium on water balance of leghorn pullets. Trial 1 involved introduction of a 4% calcium layer diet at 112, 123, 134, or 144 days of age. Introducing the layer diet early had an early but transitory effect on water intake (P less than .05) and absolute quantity of excreta moisture, although the pattern of percentage excreta moisture was not clearly defined. In a second trial, birds were moved to laying cages at 105 days, with diet change from 1 to 4% calcium occurring at 112 or 142 days. When the layer diet was offered at 112 days, percentage excreta moisture was higher from 113 to 142 days, although no difference was seen after this time. In a final experiment, introduction of a 4% calcium layer diet at either 112 or 133 days of age resulted in higher percentage excreta moisture at four measurement periods to 245 days of age, although this effect was significant only at 147 days (P less than .05). These results suggest there is a transitory effect of dietary calcium on water intake and excreta moisture content. This affect may be of concern within controlled environment buildings and with certain manure-handling systems. In commercial situations, such dietary changes are often confounded with increased dietary protein concentration, another factor known to influence water balance in pullets.

Animals↗