Between Birth Weight Research Articles

The Relationship between Birth Weight (BW), Body Mass Index (BMI) and Insulin Sensitivity (SI) in Prepubertal Caribbean Hispanic (CH) and Black African-American (BAA) Girls with Premature Adrenarche (PA)

The Relationship between Birth Weight (BW), Body Mass Index (BMI) and Insulin Sensitivity (S I ) in Prepubertal Caribbean Hispanic (CH) and Black African-American (BAA) Girls with Premature Adrenarche (PA)

Birth weight, dystocia and calf mortality in some New Zealand beef breeding herds.

Calf mortality data were summarized from four experiments, including a total of 15,694 birth records over 39 herd-years. Two experiments at Waikite and Waikeria were long-term, straightbred Angus and Hereford selection trials and the other two, at Goudies and Tokanui stations, were comparisons of 11 sire breeds mated to Angus and Herefore cows. The objective of the analyses was to study the relationship between birth weight (BW) and calf mortality for both calf sexes and for different dam age or parity groups. Overall calf death rates from birth to weaning were greater (P less than .01) from 2-yr-old than from older dams at Waikite (13.4 vs 5.3%) and Waikeria (14.7 vs 5.2%). Sex differences in death rate within 2 d of birth were small for calves from older dams. Death rate of males vs females from 2-yr-old dams were 9.1 vs 3.2% (Waikite) and 17.7 vs 10.5% (Waikeria). Mature Angus dams at Goudies had 3.7% calf deaths at birth (4.9 vs 2.4% for males vs females), a further 1.8% calf deaths to weaning and 4.6% assisted births. The BW of calves at Waikite from Angus 2-yr-old vs older dams averaged, respectively, 6.8 and 6.5% of their dam's precalving live weights. Corresponding figures for Waikeria Angus were 7.8 and 6.6% and for Waikite Herefords, 7.3 and 6.9%. Quadratic regressions revealed that, on a whole-herd basis, a small increase in BW would have no effect on total mortality at Waikeria and would decrease total mortality at Waikite; regression lines were different in shape and minimum value for calves from the two dam age groups. Quadratic models also provided an adequate fit to data from Goudies and Tokanui. There was no particular threshold BW.

255 PRENATAL METHADONE EXPOSURE: FACTORS AFFECT- ING SEVERITY OF WITHDRAWAL

There is conflicting evidence in the literature concerning the relation between maternal methadone dose during pregnancy and the severity of the withdrawal reaction experienced by the newborn. As part of an ongoing longitudinal study of children born to methadone-maintained mothers, 38 children exposed to methadone in utero were observed and their withdrawal evaluated and coded on a scale of one(mild) to 3(severe) by a trained observer. The relation between severity of withdrawal and the maternal methadone dose(MMD) prior to delivery was not significant. The relation between birth weight (BW) and severity of withdrawal was also not significant. The data indicated clear sex differences in severity of withdrawal (see above Table), with significantly more males having moderate to severe withdrawal reactions than females (x2=3.69, p<.07). This finding confirms developmental data indicating that males are more vulnerable than females to adverse environmental factors .

Heritability Estimates of Gestation Length and Birth Weight in Holstein-Friesian Cattle and their use in Selection Indexes1,2

Heritabilities of gestation length and birth weight of 958 Holstein calves were 0.60±0.12 and 0.34±0.09, respectively, after the data were adjusted for the effects of herd, sex, parity, year, and season. The least-squares means for birth weight and gestation length were 93.5lb and 277.4 days, respectively. The correlations between birth weight (BW) and gestation length (GL) were: phenotypic, 0.43; genotypic, 0.37; and environmental, 0.52. The index for selection for shorter gestation length is I = −GL + 0.10 BW and the index for selection for lower birth weight is I = −BW−0.14 GL.