Nw Sneddon

Genetic parameters for milk components including lactose from test day records in the New Zealand dairy herd

There are currently few published estimates of genetic parameters for lactose yield or lactose percentage for dairy cows. Recent trends in milk standardisation for whole milk powder have resulted in whole milk being standardised with the ratio of protein to protein-plus-lactose of at least 0.39. Currently whole milk powder produced from New Zealand milk has a protein to protein-plus-lactose ratio of 0.43, thus requiring additional lactose to be imported to maximise the return from the current product portfolio. Estimates of genetic parameters were obtained using 15,366 test day records from 4378 first-lactation cows in the Livestock Improvement Corporation sire proving scheme in the 2011–12 dairy season, distributed across 70 herds. These data included milk, fat, protein and lactose yields; fat, protein and lactose percentages; somatic cell count; days in milk; and the protein to fat ratio and protein to protein-plus-lactose ratio. Mean milk yield was 13.8 L/day, containing 5.16% fat, 3.93% protein and 5.12% lactose. Heritability estimates were 0.22, 0.35, 0.32 and 0.25 for milk yield, fat, protein and lactose percentages, respectively, which were lower than those reported in the literature but enough to allow for selection of lactose percentage.

Genetic evaluation of the total hip score of four populous breeds of dog, as recorded by the New Zealand Veterinary Association Hip Dysplasia Scheme (1991–2011)

Abstract AIM: To use estimated breeding value (EBV) analysis to investigate the genetic trend of the total hip score (to assess canine hip dysplasia) in four populous breeds of dogs using the records from the New Zealand Veterinary Association (NZVA) Canine Hip Dysplasia Scheme database (1991 to 2011). METHODS: Estimates of heritability and EBV for the NZVA total hip score of individual dogs from the German Shepherd, Labrador Retriever, Golden Retriever and Rottweiler breeds were obtained using restricted maximum likelihood procedures with a within-breed linear animal model. The model included the fixed effects of gender, birth year, birth season, age at scoring and the random effect of animal. The pedigree file included animals recorded between 1990 and 2011. A total of 2,983 NZVA hip score records, from a pedigree of 3,172 animals, were available for genetic evaluation. Genetic trends of the NZVA total hip score were calculated as the regression coefficient of the EBV (weighted by reliabilities) on year of birth. RESULTS: The estimates of heritability for hip score were 0.32 (SE 0.08) in German Shepherd, 0.37 (SE 0.08) in Labrador Retriever, 0.29 (SE 0.08) in Golden Retriever and 0.52 (SE 0.18) in Rottweiler breeds. Genetic trend analysis revealed that only the German Shepherd breed exhibited a genetic trend towards better hip conformation over time, with a decline of 0.13 (SE 0.04) NZVA total hip score units per year (p<0.001). The genetic trends of total hip score for the remaining three breeds were not significantly different from zero (p>0.1). CONCLUSIONS: Despite moderate heritability of the NZVA total hip score, there has not been substantial improvement of this trait for the four breeds analysed in the study period. CLINICAL RELEVANCE: Greater improvement in reducing the prevalence of canine hip dysplasia may be possible if screening were to be compulsory as a requirement for registration of pedigree breeding stock, greater selection pressure were to be applied and selection of breeding stock made on the basis on an individuals EBV rather than the NZVA total hip score alone.

Comparative performance in Holstein-Friesian, Jersey and crossbred cows milked once daily under a pasture-based system in New Zealand

ABSTRACT Production and efficiency of Holstein-Friesian (F), Jersey (J) and crossbred F × J milked once-a-day (OAD) were studied at Massey University dairy farm No. 1. Herd test records of milk yields, somatic cell score (SCS), live weight (LW) and body condition score (BCS) were used to model the lactation curves using a third-order orthogonal polynomial. Total lactation yields of milk (MY), fat (FY), protein (PY) and milk solids (MS = FY + PY) were calculated based on predicted daily yields. Predicted efficiencies were feed conversion efficiency (FCE; total lactation MS per kg of predicted total lactation dry matter intake [DMI]); biological efficiency (BE; total lactation MS per 100 kg of LW) and DMI capacity (DMIC; total lactation DMI per 100 kg of LW). Holstein-Friesian cows yielded 376 kg milk more than F × J cows and 1101 kg milk more than J cows per lactation. Holstein-Friesian and F × J produced similar total lactation MSY (366 and 369 kg, respectively). Jersey cows were more efficient than cows of the other breeds: FCE was 78.2, 82.3 and 86.3; BE was 69.7, 74.1 and 77.8; and DMIC was 887.9, 896.8 and 897.7 for F, F × J and J cows, respectively. There were significant differences in production and efficiency among the breeds, with J cows being more efficient per 100 kg of LW than F or F × J cows. Further research is required to compare breed profit per ha in order to conclude the best breed for OAD systems.

Estimates of genetic and crossbreeding parameters for milk components and potential yield of dairy products from New Zealand dairy cattle

ABSTRACT Milk composition can vary significantly among individual cows and breeds, and the dairy products that can be made from that milk are limited by available milk components. The objective of this research was to estimate genetic and crossbreeding parameters for lactation yields of milk, fat, protein and lactose, and use these to determine potential yields of dairy products from New Zealand dairy cattle. A mass-balance milk-processing model was used to estimate yields of milk products for 4310 first lactation heifers that produced milk in the 2010–2011 dairy season. Estimates of heritability for yields of whole and skim milk powders were moderate (0.31). Heterosis effects for product yield per lactation was significant only for cheese and butter production (P < 0.05). The use of genetic parameters and correlations for dairy product yield could increase the rate of gain for specific product yields, but have to be evaluated in conjunction with other traits of interest in breeding worth.

Dairy product production and lactose demand in New Zealand and Ireland under different simulated milk product-processing portfolios

Abstract Maximising dairy industry profitability involves maximising product returns for a specific set of costs or minimising costs for a certain level of output. A strategy currently utilised by the New Zealand dairy industry to optimise the value of exports is to incorporate imported lactose along with local milk to maximise the production of whole milk powder (WMP) while complying with the Codex Alimentarius (Codex) standards, in addition to increasing the exported product for every litre of milk. This study investigated the impact of different product portfolio strategies on lactose requirements for the Irish and New Zealand dairy industries for current and predicted 2020 milk output projections. A mass balance processing sector model that accounts for all inputs, outputs and losses involved in dairy processing was used to simulate the processing of milk into WMP, skim milk powder (SMP), cheese, butter and fluid milk of different proportions. All scenarios investigated projected an increase in production and revenue from 2012 to 2020. Higher cheese production reduced industry lactose demand through whey processing, while scenarios reliant on an increase in the proportion of WMP were associated with increased lactose deficits.

Factors that influence the survival of dairy cows milked once a day

ABSTRACT A particular emphasis has been put, by farmers, on the conformation and management of cows milked once a day (OAD). These factors might alter the culling decisions of herds after shifting from twice a day (TAD) to OAD milking. A Cox proportional hazard model was implemented to identify factors that influenced the survival of cows after the shift from TAD to OAD milking for three consecutive seasons (2013–2015). Overall, non-pregnant cows and those with low milk yield and low milk solids yield had a higher likelihood of being culled than more productive and pregnant cows. Holstein-Friesian and crossbred cows had a higher likelihood of being culled compared with Jerseys. Cows with better adaptability to milking (score > 7), and those with low pins/steeper rumps (score ≥ 4) and better udder support (score ≥ 6) were less likely to be culled. For traits such as body capacity and leg conformation, intermediate scores were associated with a lower likelihood of culling. Besides body capacity and udder support, traits including adaptability to milking, rump angle and leg conformation could also potentially be included in a new selection index for OAD dairy cattle.

Responses in lactose yield, lactose percentage and protein-to-protein-plus-lactose ratio from index selection in New Zealand dairy cattle

ABSTRACT The breeding goal of the New Zealand dairy industry is to improve the genetic capability of cows to convert pasture-based feed into farmer profit. The New Zealand dairy industry exports over 95% of milk produced and the most significant product by export volume is whole milk powder (WMP). The current selection objective, breeding worth (BW), will increase yields of protein and fat, potentially shifting milk composition further from the ideal composition for making WMP. This study aimed to investigate the correlated responses in lactose yield (LY), lactose percentage (LP) and protein-to-protein-plus-lactose ratio (P:P + L) from selection for BW, BW plus LY, BW plus LP and BW plus P:P + L. Selection for BW is predicted to have per-cow responses of 54.92 kg milk/year, 2.22 kg fat/year, 1.78 kg protein/year and 2.84 kg lactose/year. When lactose was included in the selection objective in the form of LY, LP or P:P + L, genetic responses ranged from −59.98 kg to 61.08 kg milk/year and from −2.67 kg to 3.70 kg lactose/year. The industry could reduce imported lactose requirements per tonne of WMP by 6%–11% by including lactose into the selection objective, compared with selection on BW alone.

Predicted dairy product yields and deficits of lactose for manufacturing under differing selection and manufacturing scenarios in New Zealand

The New Zealand dairy industry is pasture-based and more than 90% of milk products are exported. The breeding goal of the breeding programme of New Zealand dairy cattle is to improve the capability of the cow to convert feed into farmer profit. The breeding objective rewards yields of protein and fat but penalises milk volume and ignores lactose, despite it being an important component of milk powders. With the industry currently in deficit for lactose, this study investigated the expected response to selection over the next 10 years and its impact on the annual industry production of milk, its components and yields of dairy products based on expected cow performance, number of cows and a fixed area for dairying. After 10 years of selection (with no increase in herbage production), there was a 5% increase in milk production per hectare. Total milk exports increased by 5.9% and the lactose deficit increased by 14% when 60% of milk was processed into whole milk powder.