Browsing by Author "McNabb W"

Now showing 1 - 14 of 14
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    Animal factors affecting the cheese-making properties and the heat coagulation time of milk from dairy sheep in a New Zealand flock
    (Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-03-27) Marshall AC; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W
    The objective of this study was to evaluate the effect of animal factors on the cheese-making properties and on the heat coagulation time of milk from individual dairy sheep in a New Zealand flock. A total of 521 individual records were obtained from a seasonal pasture-based flock of 169 ewes milked once-a-day, from 50 to 182 days in milk. A statistical model was used to quantify the effects of animal factors (coat colour variety, age, litter size and stage of lactation) on the studied traits. Stage of lactation, confounded with seasonality, strongly influenced all properties of milk investigated. With the advancement of lactation, the milk took longer to coagulate after rennet addition, and the curd was softer. Higher relative cheese yield was achieved towards the end of lactation. The milk was also less stable to high-temperature treatment in late lactation. Coefficient of variation for processability traits was high and ranged from 20.2% to 58%, which can be largely attributed to stage of lactation but could also indicate room for genetic improvement of traits. Further genetic studies are underway to define animal genetic variance, heritability, and the phenotypic and genetic correlations between these processability and milk composition traits.
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    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 W
    The 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.
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    Dynamic Gastrointestinal Digestion of Bovine, Caprine and Ovine Milk Reconstituted from Commercial Whole Milk Powders
    (MDPI AG, 2024-05-02) Li S; Ye A; Cui J; Zhang Y; Ware L; Miller JC; Abbotts-Holmes H; Roy NC; Singh H; McNabb W; Polidori P
    The global dairy market has been increasingly diversified with more dairy product offerings of milk products from different animal species. Meanwhile, milk powders remain the main exported dairy product format due to their ease of transportation. In this work, we studied the structural changes, protein hydrolysis and nutrient delivery during dynamic gastric digestion and small intestinal digestion of cow, goat and sheep milk reconstituted from commercial whole milk powders. The results show that the reconstituted milks digest similarly to processed fresh milk. The digestion behaviors of the three reconstituted ruminant milks are broadly similar (gastric coagulation, kinetics of gastric emptying of protein and fat and the high digestibility in the small intestine) with some differences, which are likely contributed by the processing history of the milk powders. The delivery of individual amino acids to the small intestine differed between the early and late stages of gastric digestion, which were primarily affected by the abundance of amino acids in caseins and whey proteins but also by the difference between milk types associated with their gastric coagulation behaviors. This work showed that powdered milk is similar to fresh processed milk in digestion behavior, and the inherent differences between ruminant milks can be modified by processing treatments.
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    Effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep
    (Elsevier Ltd, 2025-01-01) Marshall AC; Vigolo V; De Marchi M; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W
    The objective of this study was to quantify the effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep from a New Zealand flock. A total of 470 test-day records, from 147 lactating ewes, were used in the statistical analyses. Protein polymorphisms observed in the RP-HPLC were self-named for purposes of the present study. Data were analyzed using a mixed linear model, including the fixed effects of ewe age, litter size, coat-colour, and stage of lactation, and, as a covariate, deviation from the median lambing date of the flock. The effects of protein polymorphisms were added to the model, one at a time. Protein polymorphisms were significantly (p < 0.05) associated with milk composition and protein profile. Polymorphisms of β-lactoglobulin were significantly associated with milk heat stability, being AB type more heat stable than AA. The other processability traits were not significantly affected by protein polymorphisms. Further studies are required to confirm the protein variants and the properties of individual protein polymorphisms.
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    Estimation of genetic parameters for production, composition and processability of milk from dairy sheep in a New Zealand flock
    (Taylor and Francis Group, 2024-06-27) Marshall AC; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W
    This paper aimed to estimate the heritability and genetic correlations for processability (milk coagulation properties, cheese yield, and heat stability), milk production, and milk composition of dairy sheep in a New Zealand flock. Test-day records from 169 ewes were obtained during the 2021–2022 season. Heritability estimates for yield traits (milk, fat, protein, and lactose yield) were moderate and ranged from 0.33 to 0.38. Whereas heritability estimates for processability traits were lower and ranged from 0.17 to 0.27. The genetic correlations indicated that poorer milk coagulation properties were associated with lower mammary health indicated by higher SCS, higher pH, and lower lactose content. Additionally, a higher ratio of casein to calcium i.e. lower availability of soluble calcium was associated with poorer milk coagulation properties. Higher yields of milk, fat, protein, and lactose were associated, but to a smaller degree, with better MCP. It is proposed that genetic improvement of dairy sheep for higher yields of fat and protein, and for lower SCS, could indirectly improve milk processability for cheese-making. However, it is recommended that larger studies involving more dairy sheep flocks are conducted to validate the present results before developing a selection index for this industry.
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    Genome-wide association studies for citric and lactic acids in dairy sheep milk in a New Zealand flock
    (Taylor and Francis Group, 2024-08-05) Zongqi A; Marshall AC; Jayawardana JMDR; Weeks M; Loveday SM; McNabb W; Lopez-Villalobos N
    The objectives of this study were to estimate genetic parameters for citric acid content (CA) and lactic acid content (LA) in sheep milk and to identify the associated candidate genes in a New Zealand dairy sheep flock. Records from 165 ewes were used. Heritability estimates based on pedigree records for CA and LA were 0.65 and 0.33, respectively. The genetic and phenotypic correlations between CA and LA were strong-moderate and negative. Estimates of genomic heritability for CA and LA were also high (0.85, 0.51) and the genomic correlation between CA and LA was strongly negative (-0.96 ± 0.11). No significant associations were found at the Bonferroni level. However, one intragenic SNP in C1QTNF1 (chromosome 11) was associated with CA, at the chromosomal significance threshold. Another SNP associated with CA was intergenic (chromosome 15). For LA, the most notable SNP was intragenic in CYTH1 (chromosome 11), the other two SNPs were intragenic in MGAT5B and TIMP2 (chromosome 11), and four SNPs were intergenic (chromosomes 1 and 24). The functions of candidate genes indicate that CA and LA could potentially be used as biomarkers for energy balance and clinical mastitis. Further research is recommended to validate the present results.
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    Impact of Mānuka Honey on Symptoms and Quality of Life in Individuals With Functional Dyspepsia: Protocol for a Feasibility Randomized Controlled Trial
    (JMIR Publications, 2025-05-21) Ombasa L; Miller J; Ware L; Abbotts-Holmes H; Tang J; Gasser O; Fraser K; Bayer S; Kemp R; Costello R; Highton A; Evans J; Merry T; Schultz M; Frampton C; Gearry R; McNabb W; Roy N; Sarvestan J
    Background: Functional dyspepsia is a common gastrointestinal condition that reduces the quality of life and increases health care costs. The lack of well-defined causes limits effective treatments. Consumers report using mānuka honey to treat gastrointestinal symptoms, although clinical evidence supporting such use is limited. Preclinical studies suggest its unique bioactive compounds may reduce gastrointestinal inflammation. Recently, 3,6,7-trimethyllumazine (Lepteridine), a natural pteridine in mānuka honey, was shown to inhibit enzymes involved in gastrointestinal inflammation in in vitro studies. Therefore, Lepteridine-standardized mānuka honey may deliver digestive health benefits. Objective: The aim of this feasibility study is to gather the data required to estimate sample size and support study logistics to design future trials. The primary objective will be preliminary assessments of the impact of Lepteridine-standardized mānuka honey on symptom severity and the quality of life in participants with mild-to-moderate functional dyspepsia. Other feasibility objectives include assessing the biological responses to mānuka honey standardized to medium and high levels of Lepteridine and measuring mānuka honey–derived metabolites in blood and urine. Methods: This is a 3-arm, parallel, controlled, double-blind, randomized feasibility study. A total of 75 healthy adults with symptoms of functional dyspepsia (Rome IV criteria) and mild-to-moderate dyspepsia severity (Short Form Leeds Dyspepsia Questionnaire) were recruited between October 2022 and September 2023. Participants were randomized into one of three groups: (1) mānuka honey standardized to contain 10 mg/kg Lepteridine, (2) mānuka honey standardized to contain 40 mg/kg Lepteridine, or (3) honey maple flavored syrup control. After a 2-week lead-in period, participants consumed 10 g of allocated intervention twice daily for 6 weeks. Throughout the study, participants completed daily bowel movement diaries and validated weekly questionnaires about their gastrointestinal symptoms and quality of life. Stool samples and 3-day diet records were collected at baseline and the end of the intervention. Blood samples were collected at baseline, weeks 2 and 4, and at the end of the intervention. In addition, 6 healthy participants without symptoms of functional dyspepsia were recruited to undergo an acute 5-hour assessment for the appearance of Lepteridine and related metabolites in plasma and urine following consumption of Lepteridine-standardized mānuka honey. The study was approved by the Northern B Health and Disability Ethics Committee. Results: Initial analysis includes 68 participants, with laboratory and data analyses being undertaken as of March 2024. The results of the primary and secondary outcomes will be published in peer-reviewed journals. Conclusions: This study will provide essential information on the potential efficacy and suitability of Lepteridine-standardized mānuka honey for designing future clinical trials investigating its effect in treating symptoms of functional dyspepsia. Trial Registration: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622001140741p; https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384094 International Registered Report Identifier (IRRID): DERR1-10.2196/66417
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    Impacts of Food Fortification on Micronutrient Intake and Nutritional Status of Women of Reproductive Age in Africa—A Narrative Review
    (Elsevier Inc. on behalf of American Society for Nutrition, 2025-07-01) Coomson JB; Smith NW; McNabb W
    More than two-thirds of women of reproductive age (WRA) in Africa are estimated to be micronutrient deficient. This is largely due to the widespread poor dietary quality and inadequate intakes of nutrient-dense foods to meet the heightened requirements for WRA. Food fortification is a cost-effective and highly recommended food-based approach for addressing these micronutrient deficiencies in low-income settings like Africa. The strategy has been implemented at different scales within the region for over 3 decades. We conducted a review to find evidence of the impact of food fortification implemented at various scales and across different population circumstances in Africa. We also sought to understand what factors may limit the impact of ongoing fortification programs on micronutrient status. We also explored findings regarding the knowledge and acceptability of fortified foods within the African population as a further barrier to the impact of food fortification on nutritional status. We found that fortification with iron and vitamin A was associated with the most variable impact from targeted and large-scale fortification programs. However, significant positive effects on nutritional status and serum biomarkers were found for food fortification with folate, iodine, and zinc among African women. Generally, fortified foods are acceptable to consumers; however, surveys assessing knowledge and preference for fortified foods found that WRA know little about food fortification and its benefits. Poor coverage of fortification, lower levels of fortificants than are recommended, and use of non-World Health Organization recommended fortificants limit the impact of food fortification on micronutrient intakes and status among WRA in Africa.
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    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 W
    Lactation 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.
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    Protein extraction from Buckwheat, Chondrus crispus, and Spelt and assessment of nutritional benefits and limitations in vitro
    (Springer Nature Limited, 2025-09-24) Cain E; Hodgkinson SM; McNabb W; Brodkorb A; Giblin L; Hayes M
    Plant protein consumption has increased globally but concerns exist regarding their ability to provide sufficient amino acids to consumers. Extraction methods that can separate protein from anti-nutritional factors have potential to increase the nutritional value of this biomass. Few studies concerning analysis of the amino acid content of plant protein extracts exist. In this work, three different protein extraction methods were used to generate protein extracts from Buckwheat, Spelt and the red seaweed Chondrus crispus. Methods used include ultra-sonication in water combined with ammonium sulphate-induced protein precipitation; an enzymatic extraction method using the enzymes Alcalase and Viscozyme, and an iso-electric precipitation extraction method using alkaline protein solubilization followed by acidic protein precipitation. Proteins extracted using the enzymatic method contained the highest proportion of essential amino acids (EAA) in viable quantities, and the method holds promise for use in the generation of alternative marine and cereal protein extracts for human consumption.
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    The Protein Composition of Bovine Milk from Once-a-Day and Twice-a-Day Milking Production Systems in New Zealand
    (MDPI (Basel, Switzerland), 2023-12) van der Zeijden M; Ellis A; Lopez-Villalobos N; Li S; Roy NC; McNabb W; Antanaitis R
    An increasing number of dairy farmers in New Zealand (NZ) have adopted a once-a-day (OAD) milking production system, and little is known about the impact of this production system on milk protein composition. The objective of this study was to evaluate the effect of OAD milking on the protein composition in milk from individual cows. Milk was sampled in early, mid-, and late lactation from cows kept at Massey University farms Dairy No. 1 (OAD milking) and Dairy No. 4 (TAD milking) in Palmerston North, NZ. The yields of total milk and milk solids, the proximate composition, and the protein composition were determined. Results showed that OAD milking yielded less milk and milk solids than TAD milking. However, no significant differences in protein, fat, and lactose contents were found. While the proportions of total casein (CN), total whey proteins, αs1-CN, β-CN, and β-lactoglobulin were not affected by the milking frequency, milk from a OAD milking system contained higher proportions of αs2-CN and κ-CN and lower proportions of α-lactalbumin. These proteins also changed differently throughout the milking season in a OAD milking system than in a TAD milking system. These changes in the protein composition of the milk observed in a OAD milking system could have implications for its processing properties and product quality.
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    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 R
    The 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.