Adjustment factors for Hereford and Angus cattle weights

Nicoll, G. B.; Rae, A. L.

doi:10.1080/00288233.1977.10427334

Cited by 5 publications

(9 citation statements)

References 18 publications

(4 reference statements)

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“…From the least-squares estimates in Table 2, ageof-dam influences on 18-month weights were of the same magnitude as those on weaning weights reported by Nicoll & Rae (1977). Brinks et al (1962), Taylor (1967, and Thomson (1968) noted similar weights after weaning, and concluded that post-weaning growth did not always compensate for pre-weaning maternal environment.…”

Section: Resultssupporting

confidence: 51%

“…In contrast to the importance of age effects on weight at weaning (Nicoll & Rae 1977), the differential postweaning environments resulted in an increasing proportion of variation in 18-month weights being attributable to herd and herd X year effects rather than to age effects. Thus, animals of the same breed and sex should be compared on 18-month weight within herds and within years of birth.…”

Section: Resultsmentioning

confidence: 68%

“…Difference between subclass means were tested by the Student-Newmans-Keuls test (Sokal & Rohlf 1969). The relative levels of importance of each main effect and each firstorder interaction were determined by comparing the percentage reductions in residual variance (Nicoll & Rae 1977).…”

Section: Analysis Methodsmentioning

confidence: 99%

“…subclass regression coefficient of weight on age additively (Method II) and multiplicatively (Methou III), as discussed by Nicoll & Rae (1977) .…”

mentioning

confidence: 99%

“…Nicoll & Rae (1977) discussed the basis of the procedures for adjusting weaning weight records in New Zealand and the need for their evaluation. In the present study, estimates of the effects of age and age of dam on the 18-month weight of Hereford and Angus males and females recorded in New Zealand are presented along with a comparison of present and alternative procedures of adjustment of weight records for these effects, From the records of the Beef Cattle Weight Gain Performance Recording Scheme (Cairney & Magnusson 1970), which preceded the present National Beef Recording Service (NBRS), weights of registered Hereford and Angus cattle recorded over at least 4 successive years in herds with at least 40 breeding cows were chosen for analysis.…”

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confidence: 99%

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Adjustment factors for Hereford and Angus cattle weights

Nicoll

Rae

1978

New Zealand Journal of Agricultural Research

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The l8-month weights of 4703 Hereford (16 herds) and 10226 Angus (33 herds) cattle, recorded over 8 years in the Beef Cattle Weight Gain Performance Recording Scheme, were analysed to estimate age and age-of-dam effects, and to evaluate present and alternative weight adjustment procedures. For least-squares analyses, l8-month weights were classified within breed and sex into herd, year-of-birth_ and age-of-dam group effects, with age at weighing as a covariate. Separate analyses evaluated the importance of each first-order interaction among herd, year, and age-of-dam group effects. All main effects and the herd x year interaction were highly significant sources of variation (P < 0.001) and were considered to be of practical importance. The mean l8-month weight of Hereford males (females) was 496.9 ± 0.7 kg (356.7 ± 1.3 kg), and of Angus males (females) was 455.4 ± 1.0 kg (318.5 ± 1.4 kg). Corresponding linear regression coefficients of weight on age were 0.55 ± 0.02 kg/day (0.45 ± 0.02 kg/day) for Hereford, and 0.64 ± 0.02 kg/day (0.36 ± 0.01 kg/day) for Angus. Adjustment for age by either additive or multiplicative linear regression coefficients of weight on age eliminated the dependence of weight on age in the data analysed, whereas adjustment by the procedure used in the National Beef Recording Service (NBRS) did not. Age-of-dam effects estimated by least-squares did not generally differ from those estimated by best linear unbiased estimation, with the exception of the weight of cattle reared by 2-year-old Hereford dams. After adjustment of weights on a sample of the data by both NBRS procedures (employing age-of-dam adjustments on 200-day weight), and by factors estimated by least-squares analysis, the rankings of individuals within breed, herd, und se>;: tended to differ between the adjustment procedures. On the basis of equalising variances within age-of-dam subclasses, it was concluded that additive adjustments for age-of-dam effects were appropriate, particularly those derived by best linear unbiased estimation.

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Section: Resultssupporting

confidence: 51%

Section: Resultsmentioning

confidence: 68%

Section: Analysis Methodsmentioning

confidence: 99%

“…subclass regression coefficient of weight on age additively (Method II) and multiplicatively (Methou III), as discussed by Nicoll & Rae (1977) .…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Adjustment factors for Hereford and Angus cattle weights

Nicoll

Rae

1978

New Zealand Journal of Agricultural Research

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Calving dates and subsequent intercalving intervals in New Zealand beef herds

Morris

1984

Anim. Sci.

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The calving dates of spring-calving cows in New Zealand Angus and Hereford herds, taken from 350 and 240 herd-years respectively, and the intercalving intervals (CI) of cows in 95 Angus and 73 Hereford herds have been summarized. The relationships of each CI with the calving date which initiated it were also analysed. Results for each breed were analysed taking account of district, herd, year and cow age (in years), a total of 35 890 Angus and 22 397 Hereford records being used. The first-calving date (FCD) was identified for each herd-year, and 0-82 of Angus and 0-75 of Hereford cows were recorded as calving within 60 days of the FCD. On a herd basis, proportionately only 0-27 of Angus and 015 of Hereford herds had calving spreads of 80 days or less (defined as the time from the FCD to the last calving date). With barren years ignored, the CIs of cows averaged 370 days (Angus) and 368 days (Hereford). Two-year-old cows had on average a CI of 12 (Angus) or 7 days (Hereford) longer in 1974-75 than older cows, and the differences were both 12 days in 1975-76. Regression analyses showed that, on average, the later the calving date within a herd-year and age group, the shorter the subsequent CI. For cows calving early in the first year, the CI increased by 7 days for Angus and 5-4 days for Herefords for each 10 days before the mean calving date for the breed. There were significant effects of district and cow age on the regression estimates. The overall regressions were not consistent with those derived from British beef industry data.

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Adjustment factors for weaning weights of Mashona cattle in Zimbabwe

Buvanendran

1990

J. Agric. Sci.

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S U M M A R YThe effects of year of birth, age of dam, sex of calf, month of birth and weaning age on weaning weights of Mashona calves on six commercial farms in Zimbabwe were estimated by least squares procedures from data of 6365 calves born 1977-85. The least squares mean weight at 205 days among farms ranged from 123 to 159 kg while the linear regression coefficients of weight on age ranged from 0-31 to 046 kg. Adjustment for weaning age by the average daily gain from birth to weaning failed to remove the dependence of adjusted weight on age. Sex was the most important source of variation and the mean difference between male and female calves was 12-9 kg. Sex difference was markedly influenced by herd production rate, being greater in herds of above average production.Weights of calves of 3-, 4-and > 11-year-old dams deviated from those of dams aged 5-10 years (mature) by 14-5, 85 and 2-9 kg, respectively. Herd mean influenced the difference between 3-year-old and mature dams, the difference increasing as herd mean declined. Herd-year specific factors seem more appropriate for sex and 3-year-old dams and an annual crop of > 50 calves would confer an advantage to herd-specific over general adjustment factors. On the basis of equality of variances within subclasses, multiplicative factors were superior to additive factors for sex of calf and month of birth; both types of adjustment were suitable for age of dam. calf> a g e o f d a m a n d a g e o f c a l f a t w e a n i n g -T h e procedures for adjustment originated from the beef Performance recording of beef herds in Zimbabwe cattle performance recording recommendations of the was started in the 1960s and farmers are encouraged United States Beef Improvement Federation (1972). to participate in the Beef Performance Testing SchemeThe applicability of these US-based adjustment (BPTS). In essence, the scheme involves collection by factors to Zimbabwean conditions and to the smaller the farmer of cow and calf records which are then indigenous Mashona needs to be established, although processed by the Department of Agricultural Techmultiplicative factors should remove most of the nical and Extension Services to provide the farmer variation due to scale. Not only is it necessary to with adjusted values of calf weights at 205 days and confirm whether the present adjustment factors used 550 days of age. The former is a measure of calf in the BPTS are suitable, but it is also important to growth to weaning and is used mainly in dam selection, determine whether other factors exist that warrant while the latter is used as a criterion in selection of correction. Even though most farmers practise seareplacement stock.sonal breeding, with calving concentrated in SepThe Mashona is one of the three indigenous breeds tember to October before the onset of rains, a of cattle in Zimbabwe and is classified as belonging to significant proportion of calves is born outside this the Sanga type, characterized by a cervical hump. It is period. The effect of month of birth thus needs t...

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Adjustment factors for Hereford and Angus cattle weights

Cited by 5 publications

References 18 publications

Adjustment factors for Hereford and Angus cattle weights

Adjustment factors for Hereford and Angus cattle weights

Calving dates and subsequent intercalving intervals in New Zealand beef herds

Adjustment factors for weaning weights of Mashona cattle in Zimbabwe

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