@conference {3672,
	title = {Calf and heifer development and the onset of puberty in dairy cows with divergent genetic merit for fertility},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {205-210},
	address = {Rotorua},
	abstract = {A research herd with divergent genetic merit for fertility was established to better understand the underlying drivers of fertility in dairy cattle. This paper describes the establishment of this herd, heifer growth and development, and the effect of divergence in fertility breeding value (FBV) on the timing of puberty. The average FBV of the high and low fertility groups of heifers was +5.6 and -4.6, respectively. The heifers were weighed fortnightly, with body condition score (BCS) and stature recorded at six, nine, 12 and 15 months of age. Weight and age at puberty were defined as the first day when plasma progesterone was >1 ng/ml in two of three consecutive once weekly samples. There was no effect of FBV on live weight (LWT), BCS, nor stature by age as the heifers matured. High-fertility heifers attained puberty at a lighter LWT (271 vs. 296 kg; SED 4.3 kg), an earlier age (358 vs. 379 days; SED 6.0 days) and a lower proportion of estimated mature LWT (51 vs. 55\%; SED 0.7\%), compared with Low-fertility heifers. Therefore, the premise that high genetic merit for fertility is positively associated with reaching puberty earlier is supported. Further work is required to support and assess the value of incorporating a puberty trait into the FBV.},
	issn = {1176-5283},
	author = {Meier S and Fisher B and Eketone K and McNaughton LR and Amer PR and Beatson P and Bryant JR and Dodds KG and Spelman R and Roche JR and Burke CR}
}
@conference {41489,
	title = {Phenotypic attributes of postpartum ovulation and other fertility measures in Friesian-Jersey crossbred cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {132-137},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Reproductive performance is an important factor contributing to on-farm efficiency and profitability. The purpose of this study was to define and quantify a set of fertility phenotypes for 352 Friesian-Jersey crossbred heifers, and determine key factors contributing to these indicators. Heats were observed and recorded prior to herd start of mating, and CIDRs were used to treat non-cycling heifers (51) once mating started. Progesterone samples were collected twice weekly, and luteal activity was identified where concentrations were >0.9 ng/ml for blood and >3.0 ng/ml for milk samples. Commencement of luteal activity was defined by either one elevated sample (CLA1) or two consecutive elevated samples (CLA2). For untreated heifers, the average intervals to CLA1 and CLA2 were 29.6 days (sd=14.3) and 34.1 days (sd=16.9) respectively. Other phenotypes were evaluated for conception and intervals to first heat, first service and successful service. Significant relationships were established between body condition score (BCS) at calving and the intervals to CLA. For every unit decline in BCS at calving there was an increase of 7.4 days to CLA1 and 8.8 days to CLA2. The evaluated fertility phenotypes, and their key contributing factors will be used in another study to identify related quantitative trait loci (QTL). },
	issn = {1176-5283},
	author = {Sanders KM and Bennett R and Spelman R}
}
@conference {40971,
	title = {Experimental designs for Quantitative Trait Loci detection in the New Zealand dairy industry},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {6-9},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Detection of loci that affect quantitative traits such as milk production has been undertaken with daughter and
granddaughter designs in the N.Z. dairy industry. Two other experimental designs, selective DNA pooling of trait
extremes and the use of first cross Holstein-Friesian{\textendash}Jersey bulls, offer the opportunity to detect more loci than the current
two designs. Selective DNA pooling involves the collective pooling of DNA from daughters at each extreme (high and
low) of the trait distribution. A sire family of 100,000 daughters with DNA pools created from the top and bottom 1\%
of progeny pooled has the same power (probability of detection) as approximately 5,000 progeny being individually
genotyped with less than 1\% genotyping effort. Crossbreeding in the New Zealand dairy industry opens up the opportunity
to identify QTL alleles that contribute to the genetic differences between the two breeds. Identification of breed specific
QTL alleles can be achieved at a power of 90\% based on some 600-1500 progeny from matings of F1 Holstein-Friesian
x Jersey bulls to F1 cows.},
	issn = {1176-5283},
	author = {Spelman R and Lopez-Villalobos N and Garrick D}
}
