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Biomedical subjects

A Cahaner

Publications and source records attributed to A Cahaner.

53 records · Page 3Linked to original sources
PubMed1992

Effects of high temperature on growth and efficiency of male and female broilers from lines selected for high weight gain, favorable feed conversion, and high or low fat content.

Male and female broiler chicks from five different broiler crosses (WI, LF, and HF = Israeli chicks selected for high body weight gain, and low and high abdominal fat, respectively; FC and WN = Dutch chicks selected for favorable feed conversion and high body weight gain, respectively) were raised at a high ambient temperature (32 to 33 C). Weight gain, protein and fat content in the carcass and feed, and protein efficiency were determined at 4, 6, and 8 wk of age. The effect of the high temperature was evaluated by comparing these data with those of similar chicks raised at a normal temperature (20 to 33 C) up to 6 wk of age. The reductions in body weight, protein gain, and feed and protein efficiency due to the high temperature increased with age and were much larger in males than in females. This trend was more pronounced in WI and WN chicks than in LF, HF, and FC chicks. Females of WI and WN crosses were as heavy as males at 6 wk and heavier at 8 wk. In LF, HF, and FC crosses, both sexes had similar weights at 8 wk. Growth reduction due to the high temperature was largest in the groups with the highest growth rate at the normal temperature (WI and WN males). Chicks with a lower growth rate and a higher capacity for energy storage in fat depots (all females, HF chicks), or a higher capacity for heat loss (FC chicks), were less affected by the high temperature. The results suggest that females should be preferred over males for broiler production in hot facilities or locations. Broiler genotypes selected for feed efficiency at the expense of fast growth may allow for a more profitable broiler production in high-temperature regions.

Adipose Tissue↗
PubMed1992

Effects of low, normal, and high temperatures on slaughter yield of broilers from lines selected for high weight gain, favorable feed conversion, and high or low fat content.

Male and female broiler chicks from five different broiler crosses (WI = Israeli chicks selected for increased body weight; LF and HF = Israeli chicks selected for low and high abdominal fat, respectively; FC and WN = Dutch chicks selected for improved feed conversion and increased body weight, respectively) were raised at low, normal, or high temperature. Slaughter yield, amount of breast meat, and abdominal fat were determined at 6 wk of age in all groups and at a body weight of 2,360 g for males and 1,965 g for females in the low- and normal-temperature groups, and at 8 wk in the high-temperature groups. Temperature, genotype, and sex influenced both absolute and relative weights of carcass, breast meat, and abdominal fat. Temperature had a negative effect on breast meat yield. Males were affected more by high temperature than females. A significant interaction between temperature and sex for breast meat yield was caused by a low yield for males at the high temperature. A similar interaction for proportion of abdominal fat was caused by a high fat content in males reared at the high temperature. Slaughter yield and especially yield of breast meat were highest in FC chickens in all comparisons.

Abdomen↗
PubMed1991

Genetic factors accountable for line-specific DNA fingerprint bands in quail.

DNA fingerprints, prepared from mixes of DNA of individuals sampled from lines of Japanese quail selected for high or low 4-week body weight, were used to evaluate the relative contribution of several evolutionary forces to genetic diversity among populations. Comparisons between lines--two replicates of each selection direction and a control unselected line--were used to determine the frequency of line-specific DNA fingerprint bands produced by each of three major evolutionary forces: 1) mutation; 2) genetic drift; 3) selection. The latter force is expected to generate line-specific bands only if there is linkage disequilibrium between DNA fingerprint loci and quantitative loci (QTLs) controlling body weight. Using probes 33.6 and R18.1, an average of 48.4 DNA fingerprint bands in each line were analyzed. On average, 27.8 bands were found to be line-specific among the 96.8 (2 x 48.4) bands analyzed in an average comparison between pairs of lines. Based on the frequencies of line-specific bands in each particular comparison, it was calculated that 21% of the line-specific bands were due to mutation, 11% due to a single genetic drift event, 11% due to selection, 21% due to the combined effects of genetic drift and selection, 22% due to double independent events of genetic drift, and 14% due to undefined factors. Although evidence was found for a high frequency of genetic changes attributable to genetic drift, and a higher than expected frequency of linkage disequilibrium, the emphasis of this report is on the methodology suggested rather than on the particular results.

Animals↗
PubMed1991

The possible prediction of fatness in broiler chickens by biochemical measurements on adipose tissue.

1. The possible prediction of fatness in 6-week-old broiler chickens was examined by measuring lipoprotein lipase (LPL) activity and lipid content in the abdominal adipose tissue. 2. Fat pad weight, as representing the degree of fatness in broiler chickens, was moderately well correlated (r = 0.54) with lipid content (g/100 g pad) and negatively correlated with LPL activity (r = 0.13). 3. It was concluded that the measurement of lipid content in samples from adipose tissue can be indicative of fatness of birds, while enzymic measurements are less valuable.

Abdomen↗
PubMed1991

DNA fingerprints of farm animals generated by microsatellite and minisatellite DNA probes.

A multi-locus DNA probe, R18.1, derived from a bovine genomic library, detected DNA fingerprints of highly polymorphic loci in hybridization to genomic DNA from poultry and sheep, and of moderate polymorphic loci in cattle and human DNA. The average numbers of detected bands in chickens and sheep were 27.8 and 21.4, and the average band sharing levels were 0.25 and 0.33, respectively. In hybridization to cattle and human DNA, the results were less polymorphic; nevertheless, individual identification is feasible using probe R18.1. The results obtained by R18.1 were compared to results obtained by Jeffreys minisatellite probe 33.6 and two microsatellite oligonucleotides, (GT)12 and (GTG)5. The total number of detected loci using probes R18.1 and 33.6 were estimated in chickens through family analysis of broilers and the maximal number of detectable loci was calculated.

Alleles↗
PubMed1991

Deoxyribonucleic acid fingerprint comparisons between selected populations of chickens.

A pair of lines of White Plymouth Rock chickens selected for high or low juvenile body weight, a pair of White Leghorn chickens selected for high or low antibody response to sheep erythrocytes, and an F1 cross between each pair of lines, were used to produce DNA fingerprints (DFP). These DFP were prepared by mixing equal amounts of DNA from several individuals of a particular population, resulting in a DFP characteristic of the population. The populations provided individuals of known genetic relationships and inbreeding levels to evaluate the sensitivity of the DFP technique with DNA mixing. Levels of band sharing between breeds were lowest, those between selected lines within a breed were intermediate, and those between the selected lines and their F1 crosses were highest. These results show that DFP analysis is sensitive to several levels of genetic relationship.

Animals↗
PubMed1991

Genotype by environment interactions using fast-growing, lean or fat broiler chickens, originating from The Netherlands and Israel, raised at normal or low temperature.

Male and female broiler chicks from five different broiler crosses (WI = Israeli chicks selected for body weight; LF and HF = Israeli chicks selected for low and high abdominal fat, respectively; FC = Dutch chicks selected for feed conversion; and WN = Dutch chicks selected for body weight) were raised under normal and subnormal temperatures. Weight gain, protein and fat content in the carcass, and feed and protein efficiency were determined at 4 and 6 wk of age, and at equal body weight. In addition to an overall effect of genotype, contrasts between Dutch (WN and FC) and Israeli (WI and LF) chicks and between chicks selected for body weight (WN and WI) or leanness (LF and FC) were examined. Temperature, genetic background, sex, and age affected all traits examined. Significant interactions were observed for weight gain, protein deposition, and feed and protein efficiency but were less evident for fat deposition. At low temperature, the broilers derived from Dutch strains had higher weight gain and protein deposition than those derived from Israeli strains; at the normal temperature the Israeli chicks performed better. The relations between body composition, weight gain, and efficiency are discussed to explain the interactions found.

Adipose Tissue↗
PubMed1990

Effect of dietary concentrations of fat and energy on fat deposition in broilers divergently selected for high or low abdominal adipose tissue.

1. Fat deposition in abdominal, mesenterial, sartorial and gizzard adipose tissues (AT), liver, breast muscle, skin and carcase was studied in male broilers, selected for high (HF) and low (LF) abdominal fat and fed on diets differing in energy density and total fat content. 2. There were no significant differences in body weight in the experimental groups. The relative weight (g/kg body weight) of the dissected adipose tissues was higher in HF than in LF birds. Fat concentration in the AT (sartorial excepted), skin and body was higher in the HF compared with the LF birds. The lines did not differ significantly in liver and breast muscle fat content. 3. Abdominal AT was affected by selection or dietary fat more than other AT and total body fat. 4. In the HF birds increasing energy density from 12.3 to 13.4 MJ/kg (dietary fat kept constant: 5.46 g/MJ) significantly increased the weight of the abdominal, mesenterial and sartorial AT. Increasing dietary fat (at both energy densities) decreased the weight of the AT, whereas increasing both energy and fat did not affect it. In the LF birds, similar but milder and insignificant trends were observed. It is suggested that this interaction has biological significance.

Adipose Tissue↗
PubMed1990

DNA fingerprints applied to gene introgression in breeding programs.

An application of DNA fingerprints (DFP) for gene introgression in breeding programs of both farm animals and plants is proposed. DFP loci, detectable by minisatellite probes, are extremely polymorphic. Individuals have unique patterns of DFP and thus can be selected for maximal genomic similarity to the recipient line, and minimal similarity to the donor line, using their DFP patterns as the criterion for similarity. This genomic selection (GS) can be performed at generations BC1, BC2 or both, and thus significantly reduce the required number of backcross generations in introgression breeding programs. The association between genomic and DFP similarity is demonstrated. Theoretical distributions and variances of the relative percentages of the donor and recipient genomes as the basis for the GS approach are presented.

Alleles↗
PubMed1990

DNA fingerprints of chickens selected for high and low body weight for 31 generations.

Two lines of White Plymouth Rock chickens that have been divergently selected for 8-week body weight for 31 generations were compared for patterns of DNA fingerprints (DFP). Digestion of DNA with HinfI and hybridization to Jeffreys' minisatellite probe 33.6 resulted in DFPs that were relatively similar within lines (bandsharing = 0.50) and less similar between lines (bandsharing = 0.22). Analyses of scorable DFP bands produced by mixing DNA from individuals within lines indicated that 48% were line-specific. Causes for the differences in DFP patterns between lines and for occurrence of line-specific bands for the two lines divergently selected for body weight are discussed.

Animals↗
PubMed1989

DNA fingerprints of poultry.

Human minisatellite probes cross-hybridize to DNA of several species of poultry (chicken, duck, turkey and goose), and detect high levels of polymorphism. The resulting DNA fingerprints are individual specific, and allow the discrimination even between closely related birds. The pattern of poultry DNA fingerprints is different from that of humans and other animals, having a higher average proportion of large DNA fragments. Pedigree analysis revealed a low number of allelic pairs of variable DNA fragments, indicating that most of the alleles are unresolved in the DNA fingerprint or too small to be detected. The total number of detectable loci in broilers, using probe 33.6, was estimated as 62, of which 13 loci are on average scoreable and available for use. Poultry DNA fingerprints can be used for individual identification, linkage studies and as an aid in breeding programmes.

Alleles↗
PubMed1987

Evaluation of two commercial broiler male lines differing in efficiency of feed utilization.

Factors potentially influencing feed conversion were studied in two lines of broilers known to differ in efficiency of feed utilization. When fed diets differing in energy, line by diet interactions were seldom significant and line effects were greater than those between diets. Chicks from the more efficient line had less plumage cover, less fat, and spent more time sitting than those from the less efficient line. These data imply that improved feed conversion is a function of several traits.

Animal Nutritional Physiological Phenomena↗
PubMed1987

Selection for early responsiveness of chicks to Escherichia coli and Newcastle disease virus.

A broiler chicken population was divergently selected for high or low early immune responses to Escherichia coli and to Newcastle disease virus (NDV) vaccines. Four selection cycles were performed in one replicate, and a single cycle in a second replicate. Selection was based on sire-family averages of a titer index (TI) calculated as the mean titer of antibodies produced by offspring vaccinated with either E. coli or NDV at 18 or 10 days of age, respectively. After the first selection cycle, TI of the early-high (EH) line were 22 and 38% greater than those of the early-low (EL) line in Replicates A and B, respectively. After four selection cycles, the average immune response to E. coli and NDV of Line EH exceeded that of Line EL by 68%. Viability was greater in the EH than in the EL line. Realized family heritabilities were .72 and .67 in Replicates A and B, respectively and the levels of response to the two antigens were not genetically correlated. The immune response of the EH line developed earlier than that in the EL line as shown by fewer nonresponders against E. coli and the higher response of this line against the two antigens at young ages. Mortality after challenge at 18 days of age and general mortality from hatching to 20 wk of age was lower in Line EH than in Line EL. Body weights at 7 wk were higher in EH than EL chicks.

Animals↗
PubMed1985

Evaluation of simultaneous selection for live body weight and against abdominal fat in broilers.

Three hundred chickens from pedigree matings in a commercial female grandparent stock were slaughtered at 7 or 9 weeks of age. Data were obtained for live body weight and various carcass parts. Coefficients of variation of abdominal fat (g and g/100 g body weight) were above 30%. Coefficients of variation of the weights of muscular and skeletal parts were much lower (about 10%) and were further reduced when calculated per 100 g body weight. Heritability of abdominal fat was higher (.82) than that of live body weight (.55) and parts: breast (.55), thighs (.31), and drumsticks (.51). Phenotypic and genetic correlations between each of the heavier parts (breast, thighs, and drumsticks) and body weight were over .8; for smaller parts (legs, wings, etc.) correlations (.49 to .79) were lower. Abdominal fat showed the lowest correlation (.26 to .36) with body weight. The genetic correlations seemed free of the part-whole relationship. Simultaneous selections for live body weight and for breast weight, or against abdominal fat, were simulated using "independent culling levels". The theoretical calculations showed that adding breast weight as a selection criterion had no advantage over selection for body weight alone due to the high genetic correlation between the two traits. However, simultaneous selection for body weight and against abdominal fat, using optimum combination of culling, was economically superior to selection for body weight alone. The advantage of this two-trait selection depends on the correlation between the traits and their relative values.

Abdomen↗
PubMedDate not supplied

Relationship between broiler chicken haematocrit-selected parents and their progeny, with regard to haematocrit, mortality from ascites and bodyweight.

A previous work of this group demonstrated that the relative haematocrit value of broilers is inherited and may serve as an indicator to susceptibility to the ascites syndrome in cold-stressed broilers. In this study, a full-pedigreed population was produced from male and female grandparent breeding stock that was selected by haematocrit and by normal selection parameters. Matings were made between low (L), medium (M) and high (H) haematocrit parents: L x L, M x M, and H x H. In their progeny, both before and after cold exposure, there was a statistically linear relationship between actual haematocrit and their H, M and L grouping (P<0.0001); heritability of the haematocrit was high (0.46-0.81). Both the low haematocrit parent and progeny groups showed an increased bodyweight. Exposure of the progeny from all the parental groups to an ascites-predisposing cold environment caused similar losses from ascites in the progeny of all three groups. Although this finding was not the same as in the previous trial where the H haematocrit group was associated with high ascites mortality, it is hypothesized that other factors, such as arterial blood saturation with oxygen, interacted in these birds at genetic or environmental levels.

Animals↗
PubMedDate not supplied

Detection of RFLP markers associated with antibody response in meat-type chickens: haplotype/genotype, single-band, and multiband analyses of RFLP in the major histocompatibility complex.

Improving disease resistance in poultry by direct selection or by selecting for immune response is hardly feasible due to the quantitative nature of these traits, their low heritability, and the difficulties associated with reliable measurements. In this situation, marker-assisted selection (MAS) is expected to be a more effective breeding approach. The major histocompatibility complex (MHC), known to affect immune response and disease resistance, was examined as a set of candidate genes for association between DNA markers and antibody response. Backcross (BC1) and F2 families were generated from a cross between lines divergently selected for high or low antibody response to Escherichia coli vaccination. Restriction fragment length polymorphism (RFLP) analysis of the highly polymorphic MHC class IV (B-G) region suggested an association with antibody response to several antigens (E. coli, SRBC, NDV). The multiband data generated with the class IV probe were used to compare the efficacies of three alternative analyses: "single-band" (carriers versus noncarriers of each RFLP band separately), "multiband" (multiple regression on all RFLP bands), and "genotype" (determined from family analysis of RFLP patterns/haplotypes). Groups of birds identified by the "multiband" analysis were identical to the haplotype-based genotypes, suggesting that the laborious step of haplotype determination can be omitted without unduly sacrificing power of analysis.

Animals↗