Ovulation and calving data from a herd selected for twin calving

Morris, C. A.; Day, A.M.; Amyes, N. C.; Hurford, A. P.

doi:10.1080/00288233.1992.10421346

Cited by 7 publications

(11 citation statements)

References 9 publications

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“…Calculations using the heritability and repeatability of TCR (individual records) gave a heritability of mean TCR per cow (based on 3 calvings per cow) of about 0.16, similar to the values actually observed. Morris et al (1992) reported repeatability and heritability estimates for ovulation rate in the twinresearch herd (0.086 + 0.034 and 0.072 + 0.089, respectively), which are of similar magnitude to the values for TCR estimated here.…”

Section: Heritability and Repeatability Estimatessupporting

confidence: 66%

“…There were 67 T cows purchased (which subsequently calved) and, at the time of purchase, they had an average age of 7.36 years and an average history of 2.39 sets of twins produced (Morris et al 1992). From the cows' history at the time of Table 1 Description of data from five private herds and the Ruakura twin-research herd (private herds selected for study on annual twin calving rate: TCR).…”

Section: Data Recorded In the Research Herdmentioning

confidence: 99%

“…Halfbred replacement daughters (T x M genotype) were generated from the M cows, and V2-bred (C x T) and (T x C) genotypes were also generated, being (a) daughters of T cows in the year of purchase, when the cows were pregnant to a bull with no twin background, or (b) daughters of T bulls and C cows when the bulls were being progeny-tested. These three V2-bred genotypes (T x M, C x T, and T x C) were progressively graded up to (T x T)-genotype status, by back-crossing with T bulls, first to generate 3 A-breds, then to "graded-pure" (T x T) cows (Morris et al 1992). Numbers of cows calving were increased from 30 to 50 per year in the mid 1980s (Morris et al 1992) to over 200 per year in the late 1980s and early 1990s, after which time numbers were reduced again; 64 cows calved in the year 2000.…”

Section: Herdmentioning

confidence: 99%

“…These three V2-bred genotypes (T x M, C x T, and T x C) were progressively graded up to (T x T)-genotype status, by back-crossing with T bulls, first to generate 3 A-breds, then to "graded-pure" (T x T) cows (Morris et al 1992). Numbers of cows calving were increased from 30 to 50 per year in the mid 1980s (Morris et al 1992) to over 200 per year in the late 1980s and early 1990s, after which time numbers were reduced again; 64 cows calved in the year 2000. During periods of static cow numbers, all or nearly all replacement heifers were retained every year for yearling mating, while the oldest cows (except multiple-twinning cows) were culled.…”

Section: Herdmentioning

confidence: 99%

“…The data reported here are from five private dairy and beef cattle herds in New Zealand with above-average TCR, and also from the Ruakura twin-research herd in which selection has been to increase TCR (Morris et al 1992). Three twinning traits were analysed here, firstly annual TCR, New Zealand Journal of Agricultural Research, 2002, Vol.…”

Section: Introductionmentioning

confidence: 99%

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Genetic variation in twin calving incidence in herds with a high phenotypic mean

Morris

Wheeler

2002

New Zealand Journal of Agricultural Research

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concluded, from the five high twinning-rate private herds selected in this study, that they had a higher heritability (average value 0.061 ± 0.010) than in published studies from industry data in other countries (average value from 13 studies, 0.027).Keywords cattle; twins; genetics; heritability Abstract Twin calving data were analysed from five private New Zealand dairy and beef cattle herds, and from the Ruakura experimental twinresearch herd founded from industry cows screened-in on their twin calving history. The objective of the study was to estimate the heritability of twin calving rate in herds with a high phenotypic mean for non-identical twin calving. The annual twin calving rate of the private herds averaged 3.36% overall, based on a total of 17 474 calving records. On average, there were 13% of cows from the selected herds with at least one twin calving in their lifetime. Heritabilities were estimated using restricted maximum likelihood (REML) procedures, with the value for annual twin calving rate for the five herds averaging 0.061 ± 0.010 (individual estimates ranging from 0.016 to 0.090), while estimates for the lifetime incidence of at least one twin calving averaged 0.16 ± 0.029 (range 0.14-0.19). The Ruakura herd had a mean annual twin calving rate over all years (1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000) of 11.2%, and in recent years (1998-2000) of 13.3%. One of the most elite cow-families in the herd (12 cows spanning five generations since the foundation cow) had an annual twin calving rate averaging 31% (seven of the cows producing at least one twin set in their lifetime), while another family of seven cows included three sets of 3-times twinning cows. Heritabilities of annual and lifetime twin calving in the Ruakura herd (cows born in 1983-1998) were 0.081 ± 0.031 and 0.25 ± 0.07, respectively. It is A01023

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Section: Heritability and Repeatability Estimatessupporting

confidence: 66%

Section: Data Recorded In the Research Herdmentioning

confidence: 99%

Section: Herdmentioning

confidence: 99%

Section: Herdmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic variation in twin calving incidence in herds with a high phenotypic mean

Morris

Wheeler

2002

New Zealand Journal of Agricultural Research

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A model of follicular development and ovulation in sheep and cattle

Soboleva

Peterson

Pleasants

et al. 2000

Animal Reproduction Science

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A note on ovarian measurements in cows with or without a history of twinning

Morris

Price

Day

1993

New Zealand Journal of Agricultural Research

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Ovaries were recovered at slaughter from 30 cows in either a twinning (T; n = 16) or control (C; n = 14) herd. Weights of ovaries and corpora lutea (CL) and records of follicle numbers and their diameters were obtained. Mean CL numbers/cow were 1.38 ± 0.12 and 1.07 ± 0.07 in the T and C cows respectively (P < 0.10). The objective was to compare the herds for ovary weights, CL weights, and follicle data, taking account of ovary side (left or right), luteal stage (Days 4-8, 9-13, 14-18, where oestrus =Day 0), and numbers of CLs on each ovary (0 or~1). Ovary weights were not affected by herd, and averaged 15.0 g when a CL was present compared with 9.1 g without a CL (P < 0.001). Single CL weights averaged 5.6 and 3.2 g in ovaries from cows which had produced single or double CLs respectively (P < 0.05). Total CL weight/cow was not significantly different in T and C herds. Numbers of ovarian follicles of given size were similar in the two herds. The diameters of the largest follicle on the right ovary and of the largest follicle overall were affected by the presence of a CL. On the right ovary, the A92066

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Ovulation and calving data from a herd selected for twin calving

Cited by 7 publications

References 9 publications

Genetic variation in twin calving incidence in herds with a high phenotypic mean

Genetic variation in twin calving incidence in herds with a high phenotypic mean

A model of follicular development and ovulation in sheep and cattle

A note on ovarian measurements in cows with or without a history of twinning

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