Genetic interrelationships among phosphorus, nitrogen, calcium, and energy bioavailability in a growing chicken population.

A random-mating population was used to study the genetic interrelationship between phytate P (PPB), Ca (CaB), N (NB), and energy bioavailability (EB), BW at 4 wk of age, relative growth (RG), and feed conversion ratio (FCR). Heritability estimates for PPB, CaB, NB, and EB were 0.09, 0.13, 0.16, and 0.10, respectively, and those of BW, RG, and FCR were 0.66, 0.15, and 0.10, respectively. Genetic correlations between PPB and BW, and FCR were moderate and negative, suggesting that improvement in PPB will impair growth. The genetic correlations between PPB and CaB, and EB and RG were positive and moderate, indicating that improvement in PPB would also lead to improved CaB, EB, and RG. Energy bioavailability was positively correlated with CaB, NB, PPB, and BW. Even though the genetic correlation between EB and the other traits measured, except RG and FCR, ranged from low to moderate, improving the ability of birds to utilize caloric energy in the feed would consequently improve PPB as well as growth. Improving PPB would reduce the amount of P in excreta and provide an additional savings if exogenous phytase were not added to poultry feed. The genetic correlation between PPB and NB was low but positive, whereas NB had a positive genetic correlation with BW. Therefore, selecting on NB will result in positive correlated responses in BW and PPB. Improving PPB and NB will not only improve productivity, but also reduce the polluting effects of P and N on the environment.

Mapping QTL for growth and shank traits in chickens divergently selected for high or low body weight.

An F(2) population (695 individuals) was established from broiler chickens divergently selected for either high (HG) or low (LG) growth, and used to localize QTL for developmental changes in body weight (BW), shank length (SL9) and shank diameter (SD9) at 9 weeks. QTL mapping revealed three genome-wide QTL on chromosomes (GGA) 2, 4 and 26 and three suggestive QTL on GGA 1, 3 and 5. Most of the BW QTL individually explained 2-5% of the phenotypic variance. The BW QTL on GGA2 explained about 7% of BW from 3 to 7 weeks of age, while that on GGA4 explained 15% of BW from 5 to 9 weeks. The BW QTL on GGA2 and GGA4 could be associated with early and late growth respectively. The GGA4 QTL also had the largest effect on SL9 and SD9 and explained 7% and 10% of their phenotypic variances respectively. However, when SL9 and SD9 were corrected with BW9, a shank length percent QTL was identified on GGA2. We identified novel QTL and also confirmed previously identified loci in other chicken populations. As the foundation population was established from commercial broiler strains, it is possible that QTL identified in this study could still be segregating in commercial strains.

Genetic influences on growth and body composition in mice: multilocus interactions.

BACKGROUND: The genetic architecture of body weight and body composition is complex because these traits are normally influenced by multiple genes and their interactions, even after controlling for the environment. Bayesian methodology provides an efficient way of estimating these interactions. SUBJECTS AND MEASUREMENTS: We used Bayesian model selection techniques to simultaneously estimate the main effects, epistasis and gene-sex interactions on age-related body weight (at 3, 6 and 10 weeks, denoted as WT3wk, WT6wk and WT10wk) and body composition (organ weights and fat-related traits) in an F(2) sample obtained from a cross between high-growth (M16i) mice and low-growth (L6) mice. RESULTS: We observed epistatic and main-effect quantitative trait loci (QTL) that controlled both body weight and body composition. Epistatic effects were generally more significant for WT6wk than WT10wk. Chromosomes 5 and 13 interacted strongly to control body weight at 3 weeks. A pleiotropic QTL on chromosome 2 was associated with body weight and some body composition phenotypes. Testis weight was regulated by a QTL on chromosome 13 with a significantly large main effect (2log(e)BF approximately 15). CONCLUSION: By analyzing epistatic interactions, we detected QTL not found in a previous analysis of this mouse population. Hence, the detection of gene-gene interactions may provide new information about the genetic architecture of complex obesity-related traits and may lead to the detection of additional obesity genes.

Modeling of parameters affecting phytate phosphorus bioavailability in growing birds.

The current study was undertaken to establish a population from an unselected random-mating chicken population for the development of a model to predict factors that affect phytate P utilization in growing birds. A population was established from a mating of 40 male and 200 female chickens from the Athens Canadian randombred population. At 4 wk of age, birds were housed in individual metabolic cages and fed a diet containing 1.06% Ca, 0.35% total P, and 0.03% available P. After 3 d of acclimatization, feed consumption (FC) was measured and excreta produced in 3 consecutive d were collected. Individual 4-wk BW, BW gain (BWG), phytate P intake (PPI), inorganic P intake (IPI), Ca intake (CaI), N intake (NI), and energy intake (EI) during the 3 d excreta collection period were also measured. Feed conversion ratios (FCR) and relative growth rate were calculated. Phytate P bioavailability (PPB), Ca bioavailability (CaB), and N bioavailability (NB) were estimated from the disappearance of the nutrients during the passage of feed through the gastrointestinal tract. Energy bioavailability (EB) was measured by bomb calorimetry as the difference in the gross energy of the feed and the energy of the excreta. The major factors affecting PPB were CaB and EB for both sexes. In the males, BW contributed significantly to PPB. However, in the females, NB also contributed significantly to PPB. Faster growing birds tended to have a reduced retention time of feed compared with slow growing birds, and as a result utilized phytate P less. Birds that are able to utilize phytate P better are putatively able to release P for energy utilization. Therefore, the birds that were able to utilize phytate P better were also better energy utilizers.

Effect of long-term divergent selection on growth characteristics in Japanese quail.

The current study was undertaken to examine the effect of long-term selection for 4-wk BW on growth characteristics in divergent lines of Japanese quail and their control. Growth rate was significantly higher in males than females in all the lines. There was a significant increase in growth rate of the females selected for increased 4-wk BW over the control females, as well as a significant decline in growth rate of males selected for decreased 4-wk BW compared to their control counterparts. It appeared that selection for increased 4-wk BW did not alter the rate of growth in the males compared to the control males; however, in the females, selection for increased 4-wk BW resulted in an increase in growth rate. On the other hand, selection for decreased 4-wk BW resulted in a decline in growth rate in males but not in the females. The dynamics of the growth curve parameters indicate that selection for decreased 4-wk BW shifted the growth curve for females as well as altering the trajectories of growth in both sexes. However, selection for increased 4-wk BW only resulted in altering the trajectory of growth in the males. Long-term selection resulted in asymmetry of response in the low and high lines. In addition, different genes may respond differently to the same selection pressure in opposite directions. The use of the 4-parameter Richards model to analyze growth data from such an experiment provided a better understanding of how selection can alter the rate and trajectory of growth to affect the genetically determined growth potential of quail. Consequently selection for increased or decreased 4-wk BW affected the sexes differently.

Hemoglobin H disease in the Al-Qatif Region of Saudi Arabia.

BACKGROUND: The Al-Qatif region in the Eastern province of Saudi Arabia has the highest prevalence of a-thalassemia genes in the Kingdom. Hemoglobin H (Hb H) disease, however, has been rarely reported. We decided therefore to verify the rarity of the disease, and characterize the presenting features in cases identified. PATIENTS AND METHODS: All patients seen in Qatif Central Hospital between September 1988 and November 1990 with low red cell indices were screened for Hb H disease, and those found positive had clinical data compiled from their hospital records and analyzed. RESULTS: Thirty-nine cases of Hb H were diagnosed. The mean age of the patients was 18 years. The mean hemoglobin was 13.5 g/dl for neonates and 7.6 g/dl for the others. The mean Hb Bart's level was 27.5% in neonates and the mean Hb H level in others was 11.1%. In addition to low red cell indices, all patients had a high red cell distribution width (RDW) mean of 25.6%. The main clinical signs were jaundice and hepatosplenomegaly. Concurrent glucose-6-phosphate dehydrogenase (G6PD) deficiency was seen in 28.2% of patients. CONCLUSION: Hemoglobin H disease is not uncommon in the Al-Qatif region of Saudi Arabia. The red cell indices may mimic iron deficiency, which should be excluded by the presence of jaundice and organomegaly. The condition often co-exists with G6PD deficiency.

The prevalence of antibodies to the human T lymphotropic virus (HTLV) in Ghana, West Africa.

We conducted a population-based serosurvey of urban areas and rural regions of southern Ghana, West Africa. Subjects (3763) of all ages were enrolled from 25 city and village sites and in studies of groups of special interest. "Positive" results were difficult to define because of a high frequency of results that were indeterminate on immunoblotting, the current standard for confirmation of HTLV-I. However, polymerase chain reaction results and HTLV type-specific discriminatory tests proved HTLV-I was present in Ghana. No HTLV-2 positivity was observed. By using strict criteria that considered indeterminate results as negative, the overall prevalence was found to be between 1 and 2% in all areas, with no difference by geographic location. Prevalence rose with age and was higher in adult women than men. However, in substudies of selected populations, we found HTLV prevalence among 124 persons with lymphomas and hematological malignancies was not different from that in the general population. Furthermore, the prevalence in prostitutes was similar to that in the general population and in pregnant women. HTLV-I is present in West Africa, but we were unable to associate HTLV-I seropositivity with malignancy or with prostitution.

Sickle cell leg ulcers in Ghana.

Twenty five (17 male, 8 Female) sickle cell disease patients with 30 leg ulcers were studied over a 3 year period (January 1985 to December 1987) to provide information on the pathogenesis, course and management. There were 23 patients with homozygous sickle cell and 2 patients with sickle cell haemoglobin C disease. The mean age was 28 years (range 15-44 years). An antecedent history of trauma was obtained in 40% of the patients and 96% had a previous history of leg ulcer. The major site affected (93%) was the skin around the malleoli. In 68% of the patients a single organism was isolated and the commonest bacteria were Pseudomonas species, Staphylococcus aureus, Proteus species and B haemolytic streptococci. The major complications encountered were equinovarus deformity (36%) and chronic periosteitis (32%). The main topical antimicrobial used was Eusol either alone (52%) or in combination with Metronidazole (32%) or honey (12%). Complete healing occurred in 40% of patients, partial healing with deterioration in 16% and no significant change in 44%. Admission and bed rest were the best determinants of complete healing of the chronic ulcers.

Acupuncture analgesia in severe sickle cell painful crisis

Sixteen adult patients (8 males and 8 females) with severe sickle cell painful crisis were given acupuncture for pain relief. Good response was achieved in 12 (75 per cent) patients and the remainder had moderate pain relief. All patients were discharged home the same day feeling better