Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Candidate gene search for milk production and composition, milk coagulation properties, and milk protein profile in dairy sheep from a New Zealand flock(Taylor and Francis Group, 2025-07-11) Marshall AC; Lopez-Villalobos N; Vigolo V; Marchi MD; Loveday SM; Weeks M; McNabb WThe objective of this study was to perform genome-wide association analysis and thus search for candidate genes for milk production and composition, milk coagulation properties (MCP), and milk protein profile in dairy sheep from a New Zealand flock. After quality control, 45,801 single nucleotide polymorphisms (SNPs) were included in the analysis, 147 ewes, and 470 individual records. A total of 87 SNPs and 55 candidate genes were found across Ovis aries autosomes (OAR) 2, 3, 6, 16, 18, 20, 25, and 26. Of particular importance, were the candidate genes PDZRN4 for milk yield, and BMP2K for contents of αs1- and αs2-caseins. No SNPs were found in the casein genes, LALBA or PAEP. Only one SNP was significant for MCP, and overall, the genetic architecture of MCP was similar to that of ratio of casein to calcium, pH, lactose, and the ratio of casein to protein. Further studies with larger flocks and with genomic imputation are required to validate the findings of this study before incorporating markers or genes into breeding programmes.Item Lactation curves for milk, fat and protein in dairy cows under regenerative versus conventional farming practices(Taylor and Francis Grou, 2024-11-10) Moreno-Gónzalez Y; López-Villalobos N; Donaghy D; López IF; MacGibbon A; Holroyd SERegenerative agriculture aims to utilise more diverse pasture species and enhance animal performance through sustainable soil management and pasture quality. This study evaluated the influence of regenerative and conventional farming on dairy cow performance and milk production under different pasture mixes and management strategies. Monthly herd test records were used to model individual lactation curves for daily milk, fat, and protein yield for the 2022–2023 season using random regression with third-order orthogonal polynomials. Total yields were calculated from predicted daily yield. Treatments were SPCM: Standard pasture under conventional management, DPCM: Diverse pasture mix under conventional management, and DPRM: Diverse pasture mix under regenerative management. Total milk yield was similar across treatments, averaging 3370 kg (SPCM), 3649 kg (DPCM), and 3626 kg (DPRM) for the 2022–2023 season. No significant differences were observed in fat, protein, milk solids yield, or milk composition. Cows on diverse pastures, regardless of management approach, showed heavier liveweights than those on standard pastures. DPCM and DPRM cows averaged 474 kg, significantly greater than SPCM cows at 464 kg (P < 0.0001), likely due to longer grazing rotation and higher post-graze mass. These findings suggest that pasture species diversity, regardless the management, enhances liveweight without affecting milk composition.Item Identification of candidate novel production variants on the Bos taurus chromosome X(Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association, 2023-11) Trebes H; Wang Y; Reynolds E; Tiplady K; Harland C; Lopdell T; Johnson T; Davis S; Harris B; Spelman R; Couldrey CChromosome X is often excluded from bovine genetic studies due to complications caused by the sex specific nature of the chromosome. As chromosome X is the second largest cattle chromosome and makes up approximately 6% of the female genome, finding ways to include chromosome X in dairy genetic studies is important. Using female animals and treating chromosome X as an autosome, we performed X chromosome inclusive genome-wide association studies in the selective breeding environment of the New Zealand dairy industry, aiming to identify chromosome X variants associated with milk production traits. We report on the findings of these genome-wide association studies and their potential effect within the dairy industry. We identify missense mutations in the MOSPD1 and CCDC160 genes that are associated with decreased milk volume and protein production and increased fat production. Both of these mutations are exonic SNP that are more prevalent in the Jersey breed than in Holstein-Friesians. Of the 2 candidates proposed it is likely that only one is causal, though we have not been able to identify which is more likely.Item The effects of breed and genomic inbreeding on milk, fat and protein lactation yields and fertility traits in pasture-based dairy cows in Argentina(Cambridge University Press, 2024-05-24) Beribe MJB; Carignano HA; Poli MA; Lopez-Villalobos NThe objective of the current study was to evaluate the effects of breed and genomic inbreeding on 305-day lactation yields of milk, fat and protein; and fertility traits of pasturebased dairy cows in Argentina. The genomic inbreeding and heterozygosity of 890 firstlactation cows and 27 bulls were calculated through methods based on the genomic relationship matrix and run of homozygosity using 44 174 SNPs. Cows were classified into 4 breed groups: Holstein, Holstein crossbred, Holstein-Jersey crossbred, and Jersey crossbred. The effect of genomic inbreeding was not significant on production traits, but inbred cows increased 3.0 days calving to conception interval per 1% genomic inbreeding. On average, purebred Holstein cows produced 1119 kg milk, 22 kg fat, and 30 kg protein more than Jersey crossbred cows. In the case of the fertility traits, Jersey crossbred cows had 45 days shorter calving to conception interval than purebred Holstein cows. A possible reason for the non-significant effects of genomic inbreeding of production and fertility traits is that these effects were evaluated in a crossbred population in which levels of heterozygosity would operate to some extent in the opposite direction to levels of genomic inbreeding.Item Can the use of digital technology improve the cow milk productivity in large dairy herds? Evidence from China's Shandong Province(Frontiers Media S.A., 2022-12-02) Qi Y; Han J; Shadbolt NM; Zhang Q; Naseer MAURIntroduction: Improving milk productivity is essential for ensuring sustainable food production. However, the increasing difficulty of supervision and management, which is associated with farm size, is one of the major factors causing the inverse relationship between size and productivity. Digital technology, which has grown in popularity in recent years, can effectively substitute for manual labor and significantly improve farmers' monitoring and management capacities, potentially addressing the inverse relationship. Methods: Based on data from a survey of farms in Shandong Province in 2020, this paper employs a two-stage least squares regression model to estimate the impact of herd size on dairy cow productivity and investigate how the adoption of digital technology has altered the impact of herd size on dairy cow productivity. Results: According to the findings, there is a significant and negative impact of herd size on milk productivity for China's dairy farms. By accurately monitoring and identifying the time of estrus, coupled with timely insemination, digital technology can mitigate the negative impact of herd size on milk productivity per cow. Discussion: To increase dairy cow productivity in China, the government should promote both small-scale dairy farming and focus on enhancing management capacities of farm operators, as well as large-scale dairy farms and increase the adoption of digital technologies.Item Udder and teat morphology traits associated with milk production and somatic cell score in dairy sheep from a New Zealand flock(Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024) Marshall AC; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W; Handcock RThe objective of this study was to estimate the phenotypic correlations between udder and teat morphology traits, milk production traits, and somatic cell score in dairy sheep from a flock in New Zealand. A total of 162 lactating ewes were scored for morphology traits during the milk production season of 2021–2022. The 130-d lactation yields of milk, fat, protein, and lactose were obtained with 2–4 test-days from each ewe and modelled using random regression with orthogonal polynomials. Age had a significant effect on all udder and teat traits. Coat-colour (genetic variety within the breed; white or black) was a significant effect for teat angle and udder separation. Udders that were above the hook were associated with lower milk, fat, protein, and lactose yields. Udders with well-defined separation between halves were associated with higher milk, protein, and lactose yields, and with lower somatic cell count. Well-attached udders were associated with lower fat yield and lower somatic cell score. Teats with a backwards angle were associated with lower milk and lactose yields. Further studies are needed to estimate heritability and genetic correlations between these traits to determine whether these traits should be implemented in breeding programs for dairy sheep in New Zealand.Item Low Birthweight Beef Bulls Compared with Jersey Bulls Do Not Impact First Lactation and Rebreeding of First-Calving Dairy Heifers—A Case Study in New Zealand(MDPI (Basel, Switzerland), 2022-03) Coleman L; Martín N; Back P; Blair H; López-Villalobos N; Hickson R; Bittante G; Mantovani RDairy heifers in New Zealand are typically naturally mated by Jersey bulls to produce low-value non-replacement offspring sold for slaughter a few days after birth. Producing a beef-sired calf from a dairy heifer will increase the value of these calves for beef production but may compromise the subsequent career of the animals, in terms of milk production, rebreeding success, health, or survival of the heifer. This study aimed to determine the impact of low birthweight Angus and Hereford bulls versus breed-average Jersey bulls on the reproduction and production traits of first-calving dairy heifers. The experiment included 304 heifer-calf pairs over 2 years. Calves sired by Angus and Hereford bulls were 3.5–4.4 kg and 3.7–6.8 kg heavier than Jersey-sired calves and had a 4.2% and 9.3% incidence of assistance at birth for normally presented calves over the 2 years, respectively. No normally presented Jersey-sired calves were assisted. There was no difference in body condition score, pre-calving live weight, milk production, pregnancy rate, inter-calving interval, re-calving day, and 21-day re-calving rate of heifers mated to the different breeds of bulls. The results indicate that the Angus and Hereford bulls with low birthweight and high direct calving ease estimated breeding values (EBV) can be used to produce calves of greater value than Jersey-sired calves without impacting dairy heifer production. However, a small increase in assistance at calving could be expected.Item Service Sire Effects on Body Condition Score, Milk Production, and Rebreeding of Mixed-Aged Dairy Cows Bred to Angus and Hereford Bulls—A Case Study in New Zealand(MDPI (Basel, Switzerland), 2021-12-01) Coleman L; Back P; Blair H; López-Villalobos N; Hickson R; Meyer UBeef-breed bulls are used in dairy herds to produce a calf of greater value for finishing than calves sired by dairy bulls. There is limited research about which beef-breed bulls are most appropriate, and whether any negative impact on cow performance in terms of milk production and rebreeding should be considered. The aim of this case study was to compare the body condition score, milk production, and rebreeding performance of mixed-aged dairy cows bred to a selection of Angus and Hereford beef-breed bulls. Body condition score, post-calving live weight, milk production, rebreeding performance, and survival of 952 mixed-aged dairy cows artificially bred to 65 Angus and Hereford bulls were compared. There was no effect of service sire on post-calving live weight, days in milk, milk production, or inter-calving intervals of mixed-aged cows. Service sire had an effect on the calving day due to differences in gestation length (p < 0.001), although this did not translate into an effect on days in milk. A longer gestation length negatively influenced pregnancy rates, and greater birth weight of the calf negatively influenced survival to rebreeding (p < 0.05), indicating the potential for an effect of service sire. Selection of beef-breed service sires for dairy cows should include emphasis on lighter calves and shorter gestation lengths. The general absence of the service sire effect on the parameters measured in this study indicated that any of the service sires used in this experiment would be appropriate for use over dairy cows.Item Modelling Lactation Curves for Dairy Sheep in a New Zealand Flock(MDPI (Basel, Switzerland), 2023-01-19) Marshall AC; Lopez-Villalobos N; Loveday SM; Ellis A; McNabb WLactation curves were modelled for dairy sheep in a New Zealand flock, providing information on the lactation yields of milk, fat, protein, and lactose, corrected for 130 days of milking. From 169 ewes, a total of 622 test-day records were obtained during the milk production season of 2021-2022 (from October to January). The flock produced an average of 86.1 kg of milk, 5.1 kg of fat, 4.5 kg of protein, and 4.1 kg of lactose, and moderate to large coefficients of variation were observed (27-31%) for these traits. The lactation persistency of milk, fat, protein, and lactose yields ranged from 52.3 to 72.7%. Analyses of variance for total yield and persistency were performed with an animal model that included the fixed effects of age (parity number), litter size, coat colour, and milking frequency (days in twice-a-day milking) and random residuals. Age and milking frequency were the only factors that significantly affected the yields of milk, fat, protein, and lactose. Age significantly affected the lactation persistency of milk and lactose yields, whereas litter size affected the persistency of protein, and milking frequency affected the persistency of fat. This study on this single flock provides valuable experience for a larger-scale animal breeding programme in New Zealand.Item The Effect of Lameness on Milk Production of Dairy Goats(MDPI (Basel, Switzerland), 2023-05-23) Jaques N; Turner S-A; Vallée E; Heuer C; Lopez-Villalobos N; Moraleda GR; Hall SJGLameness on dairy goat farms is a welfare concern and could negatively affect milk production. This study's objective was to evaluate the effects of clinical lameness on the daily milk production of dairy goats. Between July 2019 and June 2020, 11,847 test-day records were collected from 3145 goats on three farms in New Zealand. Locomotion scoring of goats used a five-point scoring system (0 to 4). The dataset was split into two groups by lactation type, where goats were classified as being in seasonal lactation (≤305 days in milk) or extended lactation (>305 days in milk). A linear mixed model was used to analyze datasets using milk characteristics as the dependent variables. Severely lame goats (score 4) in seasonal and extended lactation produced 7.05% and 8.67% less milk than goats not lame, respectively. When the prevalence of severe lameness is between 5 and 20% of the herd, the estimated average daily milk income lost was between NZD 19.5 and 104 per day. This study established the negative impact of lameness on milk production and annual income in dairy goats on three farms.