Biomedical subjects
Publications and source records attributed to J F Hayes.
Lithiation and alkylation of a 2-isopropylidineaziridine bearing an (S)-alpha-methylbenzyl group on nitrogen proceeds with high levels of diastereocontrol (80-90% de).
(S)-Coniine is made using a reaction which assembles the piperidine ring by the sequential formation of four new chemical bonds and installs the C-2 stereogenic centre with high levels of diastereocontrol (90% de).
Data were evaluated from a purebred Holstein herd (n = 1274) kept near Khartoum, a hot and dry area, from 1990 to 1996. The mixed model procedure in SAS was used to analyse the reproductive traits. The mean gestation length, days dry, number of services per conception, days from calving to first oestrus, days from calving to conception, calving interval and breeding efficiency were 279 days, 104 days, 4.2, 85.8 days, 208.9 days, 486.2 days and 74.9%, respectively. Factors that had significant effects (p < 0.01) on all the reproductive measures under study were the year and month of calving, and parity. The heritability estimates for all traits under investigation were zero. The repeatability estimates for the numbers of services per conception, days from calving to conception, days from calving to first oestrus and calving interval were 0.21 +/- 0.021, 0.12 +/- 0.024, 0.03 +/- 0.018 and 0.00, respectively. The phenotypic correlation for calving interval with numbers of service per conception was 0.05, that with days from calving to first oestrus was 0.06 and that with days from calving to conception was 0.07. Other correlations ranged from 0.00 to 0.28. The simple correlation coefficients between production and reproductive measures ranged from -0.06 to 0.45.
A herd of 370 Holstein-Friesian cows were maintained in Central Sudan, Khartoum for intensive dairy production during the period 1990-1996. The area is characterized by high temperatures during the day and cools down at night, with an average thermal-humidity index (THI) of 74.8. The average adjusted lactation milk yield, milk yield per day, milk yield per day of calving interval and lactation length of the animals in the herd were 5117 +/- 123 (SE) kg, 14.7 +/- 0.25 kg, 11.3 +/- 0.36 kg and 350 +/- 8.0 days, respectively. Heifers calved at 25.2 +/- 2.3 (SD) months of age. The variation was large, which suggested large environmental fluctuations. Sire variance contributed 1.35% and 19.6% to the total variance in cows and heifers, respectively, while cow within sire contributed 19%. The heritabilities of total lactation yield, 305-day yield, milk per day of lactation, milk per day of calving interval, and lactation length in heifers were 0.78 +/- 0.24, 0.36 +/- 0.34, 0.39 +/- 0.24, 0.23 +/- 0.23, and 0.23 +/- 0.22, respectively. In cows, the heritability estimates were 0.05 +/- 0.24, 0.06 +/- 0.24, 0.08 +/- 0.24, 0.00 and 0.00 for the same traits, respectively. The repeatabilities of total lactation yield, 305-day yield, milk per day, milk per day of calving interval and lactation length were 0.02 +/- 0.03, 0.22 +/- 0.03, 0.17 +/- 0.02, 0.05 +/- 0.02 and 0.00, respectively. Regression analysis showed that, for each unit increase in THI, milk yield decreased by 0.29 +/- 0.04 kg. The stress usually caused by the combined effects of temperature and humidity was not severe in this area.
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Bovine ornithine decarboxylase (ODC) genomic clones were isolated from a bacteriophage lambda DASH genomic library. A total of 9452 bp sequence was determined which covers the entire sequence of the bovine ODC gene. Sequence analysis showed that the bovine ODC gene consisted of 12 exons which encode a protein identical to that inferred from a bovine ODC cDNA. Comparison of the structure and nucleotide sequence of the bovine, human and mouse ODC genes revealed that the gene was highly conserved. Primer extension analysis demonstrated that the transcription start point of bovine ODC mRNA was located 378 bp upstream from the A residue in the translation initiation codon. The 5'-untranslated region (UTR) of ODC mRNA was highly G + C rich, particularly in its 5'-most portion, and computer predictions suggested a very stable secondary structure for this region, with an overall free energy of formation of -134.4 kcal/mol. Conserved sequences and potential promoter elements including a TATA box, a possible CCAAT element, SP1 ranscription factor binding sites (GC boxes) and cAMP response elements (CRE) were identified in the 5'-flanking region of the gene. Two polymorphic restriction sites, a TaqI and a MspI, were mapped to the ODC gene and PCR-based methods for detection of the 2 polymorphisms were developed.
Sequence variations in the bovine growth hormone (GH) gene were investigated by single strand conformation polymorphism (SSCP) analysis of seven amplified fragments covering almost the entire gene (2.7 kb). SSCPs were detected in four of these fragments and a total of six polymorphisms were found in a sample of 128 Holstein bulls. Two polymorphisms, a T-->C transition in the third intron (designated GH4.1) and an A-->C transversion in the fifth exon (designated GH6.2), were shown to be associated with milk production traits. GH4.1c/GH4.1c bulls had higher milk yield than GH4.1c/GH4.1t (P < or = 0.005) and GH4.1t/GH4.1t (P < or = 0.0022) bulls. GH4.1c/GH4.1c bulls had higher kg fat (P < or = 0.0076) and protein (P < or = 0.0018) than GH4.1c/GH4.1t bulls. Similar effects on milk production traits with the GH6.2 polymorphism were observed with the GH6.2a allele being the favorable allele. The average effects of the gene substitution for GH4.1 and GH6.2 are similar, with +/-300 kg for milk yield, +/-8 kg for fat content and +/-7 kg for protein content per lactation. The positive association of GH4.1c and GH6.2a with milk production traits may be useful for improving milk performance in dairy cattle.
A polymerase chain reaction (PCR)-based method for detection of a MspI-restriction fragment length polymorphism (RFLP) in the bovine ornithine decarboxylase gene was developed, and the allele frequencies of the polymorphism in two groups of Holstein bulls representing progeny-tested bulls during the 1950s-1960s and 1980s, respectively, were estimated. The frequencies of the MspI(-) allele ere 0.229 and 0.077 and that of MspI(+) were 0.771 and 0.923 in the progeny-tested bulls of the 1950s-1960s and 1980s, respectively. The difference in allele frequencies between the two groups was statistically significant (P < 0.005). Genetic drift could be responsible for the changes in allele frequencies; however, it could also be possible that selection for milk production was associated with the changes of the allele frequencies in the two bull populations.
A cDNA coding for ornithine decarboxylase (ODC) was isolated from a bovine liver cDNA library. The clone (1758 base pairs) consisted of 5'- and 3'-untranslated regions of 185 and 187 nucleotides, respectively, and an open reading frame of 1383 nucleotides encoding an ODC protein (M(r) 51,342 daltons) of 461 amino acids. Comparison of the nucleotide and the predicted amino acid of the cDNA with other mammalian ODCs showed a very high degree of homology both at the DNA and protein levels. The bovine ODC mRNA was identified by northern blot to be a single species with a molecular size of 2.35 kilobase pairs. Primer extension analysis indicated that the 5'-untranslated region of the bovine ODC mRNA was 312 nucleotides long. Southern blot analysis of bovine genomic DNA revealed restriction fragment length polymorphisms when cleaved with restriction enzymes PstI, MspI, TaqI, and Bg/I.
Data on 82,835 Holstein cows, daughters of 703 sires and with first calvings from 1979 to 1984 in 2384 herds enrolled in Quebec Dairy Herd Analysis Service, were analyzed for relationships of first lactation traits with traits for partial and total lifetime performance using multitrait REML methodology and a linear mixed model. Effects of herd-year-season, age at first calving, and proven sires were considered to be fixed, and effects of young sires and residuals were considered to be random. All known additive genetic relationships among sires were accounted for in construction of the relationship matrix. Individual lactation records were precorrected for the fixed effect of year and month of calving before lifetime totals were calculated. Each cow was given at least a 5-yr opportunity for production. All genetic and phenotypic correlations were positive except correlations of first lactation percentage traits. Correlations with partial lifetime performance were highest. Genetically, first lactation milk yield was highly correlated with most measures of lifetime performance, .64 to .92; correlations with measures of longevity were relatively smaller. Given high positive genetic correlations, selection singly on first lactation milk yield will improve all measures of lifetime performance; however, some measure of longevity should be considered in selection programs of dairy cattle.
Data on 82,835 Holstein cows, daughters of 703 sires and with first calving from September 1979 to December 1984 from 2384 herds enrolled in the Quebec Dairy Herd Analysis Service, were used to estimate genetic and phenotypic parameters of partial and total lifetime performance traits with REML. The model included herd-year-season of first calving, age at first calving, and proven sires as fixed effects and young sires and residuals as random effects. Individual lactation records were precorrected for year-month of calving before lifetime totals were calculated. Only cows with at least 5 yr of opportunity for production were analyzed. The ranges of heritability estimates were .11 to .13 for lifetime production and profit, .07 to .09 for measures of longevity, and .28 to .32 for yield per day of productive life. Correlations among total lifetime yield and profit traits and among measures of longevity were > or = .93. Genetic and phenotypic correlations, respectively, of early partial (two parities total) with total life-time yield and profit and longevity traits ranged from .81 to .94 and .66 to .78. Selection on early performance seems to be desirable and, given the high positive genetic correlations, should increase both lifetime yield and longevity.
Repeatabilities and heritabilities of days to first service, days open, and number of services per conception were estimated from 235,589 records on 80,333 Holstein cows, daughters of 306 sires obtained from the Quebec Dairy Herd Analysis Service, by REML. The model for statistical analyses included herd-year-season as a fixed effect and sire, cow (sire's daughter) within sire, and error as random effects. Variance components corresponding to sire, cow within sire, and error were then estimated by REML. Heritability estimates, obtained from the sire variance component, were .03, .05, and .03 for days to first service, days open, and number of services per conception, respectively. Repeatability estimates, obtained from the sire and cow within sire variance components were .08, .10, and .07 for days to first service, days open, and number of services per conception, respectively.
Genetic and phenotypic correlations were estimated between 6 lifetime production and 28 linearized type traits using REML. The data set contained 34,322 cows, each with a record for all 34 traits. The analyses accounted for the fixed effects of herd, year-month, classifier, age at first calving, and stage of lactation. Heritabilities were low for lifetime traits and moderate for most type traits except stature, size, capacity, thurl width, and pin setting, which had high heritabilities. Most phenotypic correlations between lifetime production and type were in the range of .15 to .20 except for capacity, rump, and feet and legs, which were around .07. Genetic correlations were strong between lifetime production and angularity (.44 to .55) and dairy character (.53 to .56). Genetic correlations were low to moderate between life-time production and stature (.14 to .25), size (.07 to .18), texture (.19 to .26), style (.11 to .27), head (.15 to .23), pin setting (.10 to .16), rear udder (.19 to .25), and rear attachment (.10 to .22). The only notable negative genetic correlations were lifetime production with rear heel (-.16 to -.27), thurl width (-.18 to -.24), and fore udder (-.05 to -.11).
Heritabilities and genetic and phenotypic correlations among yields of milk, fat, protein, and percentages of fat and protein were estimated from 40,984 first lactation records of daughters of 488 young and 75 proven Holstein sires using multivariate REML and a sire model accounting for relationships and sire groups. Proven sires were treated as fixed effects. Heritabilities for yields of milk, fat, protein, and percentages of fat and protein were .29, .31, .25, .65, and .61, respectively. Genetic correlations of milk with yields of fat, protein, and percentages of fat and protein and correlations of fat yield with fat percentage were .45, .79, -.49, -.54 and .56, respectively. Genetic correlations among yields and among percentage of fat and protein were the same (.62). Genetic and phenotypic correlations of protein percentage with fat and protein yields and correlations of fat percentages with protein yield were small (-.13 to .11). Phenotypic correlations were .73 to .90 among yields of milk, fat, and protein; -.31 for milk and fat percentage; -.39 for milk and protein percentage; and .38 for fat yield and fat percentage. Estimates were consistent with an earlier study utilizing data from the same population and also with other reports.
Two different methods were used to determine kappa-casein genotypes of Holstein sires. In the earlier procedure, genotypes of sires were deduced by analyzing frequency distribution data of kappa-casein variants obtained through typing of milk samples from daughters by electrophoresis. The second method involved direct analysis of DNA obtained from semen samples of the sires. The polymerase chain reaction was used to amplify a 99-bp region from the kappa-casein gene that contains nucleotide substitutions that are diagnostic of variants A and B. Identity of the amplified product was confirmed by sequencing. Results obtained by both methods of genotyping were similar. For the 42 sires that were analyzed by both methods, the distribution of kappa-casein genotypes were 31 AA, 11 AB, and 0 BB. The frequency of B allele for kappa-casein in the sire population studied was lower than in larger Holstein cow populations. Due to the high demand for kappa-casein B milk by the dairy industry, it might be advantageous to increase this allele in the dairy cattle population by identifying sires with homozygous kappa-casein B and using them more frequently as service sires.
Restricted maximum likelihood was used to estimate repeatabilities and heritabilities for calving ease from a data set of 636,972 Holstein parturitions obtained from the Quebec Dairy Herd Analysis Service. Subsets of the data, chosen to reflect different stages of cow maturity, were analyzed separately and compared. Initial least squares analyses were used to define the fixed effects to include in the model. The effects of herd-year-season, sex of calf, parity, and sex by parity interaction were significant in all subsets. Age and parity by age interaction were significant in subsets with primarily younger animals. Variances for sire of calf, cow, and residual effects were then estimated by REML. Repeatabilities ranged from 5.98 to 7.87% and heritabilities for calving ease as a direct effect ranged from 1.97 to 4.70%.
Heritabilities of, and genetic and phenotypic correlations between, type traits and the arithmetic mean of lactational SCC were estimated using minimum norm quadratic unbiased estimation and two multitrait REML methods. Three sets of data were analyzed. Heritabilities of all traits were small. For SCC, heritabilities varied between .09 and .11 and for type traits, between .08 and .14. Genetic correlations between SCC and type traits varied between -.22 and .30. Phenotypic correlations were very low. In general, correlations indicate a rather favorable association between SCC and udder conformation traits; that is, a desirable score on type would be associated with low SCC in milk.
Type information collected by the Holstein Association of Canada was combined with calving ease data from the Quebec Dairy Herd Analysis Service. Type traits considered were overall score, general appearance, dairy character, capacity, rump, rump thurl width, rump pin setting, and set of rear legs. Calving ease was considered as a direct effect and as a maternal effect in both heifers and adult cows. After editing there were 24,618 type records, 47,023 direct effect calving ease records, and 37,068 maternal effect calving ease records from 107 sires in the analyses of heifer data. there were 26,996 type records, 16,4726 direct effect calvin ease records, and 45,261 maternal effect calving ease records in the analyses of calving involving adult cows. Multiple-trait REML was used to estimate genetic correlations between calving ease and type. The heritability of calving ease in heifers was approximately 4%, for both the direct and maternal effect, and in adult cows was approximately 1.5%. Heritability of the type traits ranged from 4 to 45%. There was a tendency for the genetic correlations between type and the direct effect of calving ease to be opposite in sign to the genetic correlations between type and the maternal effect of calving ease and for the absolute value of the correlations to be lower in adult cows than in heifers.