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Item Genetic and genomic studies on milk production and composition, and longevity in New Zealand dairy goats : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatu, New Zealand(Massey University, 2020) Scholtens, MeganThe New Zealand dairy goat industry is important for producing and exporting high-quality specialised dairy products aimed at niche markets. Efforts to increase the quantity and composition of goat milk will improve profits for farmers and deliver significant economic benefits to New Zealand. However, no formal program exists for the genetic improvement of dairy goats. Therefore, the general aim of this thesis was to perform genetic and genomic studies that contribute to the design of the breeding program for New Zealand dairy goats. The first studies estimated variance components and genetic parameters of total lactation yields of milk, fat and protein, somatic cell score and longevity. The main findings suggest sufficient variation and favourable genetic correlations between these traits, supporting their inclusion into a selection index that predicts profit per animal. A random regression test-day model was then used to predict lactation curves of milk, fat, protein and somatic cell score. Using this model for genetic evaluation will enable the dairy goat industry to move from total yields into the prediction of lactation curves, enabling more accurate predictions and the opportunity of selecting for extended lactations. The first genome-wide association study of dairy goats in New Zealand was conducted using 3,732 animals genotyped with the Caprine 50K SNP chip. A highly significant region on chromosome 19 was associated with yields of milk, fat and protein, and somatic cell score, and a region on chromosome 29 was associated with somatic cell score. A prototype single-step BayesC model was developed to predict genomic breeding values and demonstrated that including genomic information into the evaluation can increase the accuracy of predictions compared to the traditional methods based on pedigrees alone, which is currently implemented in the New Zealand dairy goat industry. This thesis demonstrates that a single-step prediction model that uses genomic information would put the New Zealand dairy goat industry in a very good position to implement a genomic selection scheme. Further studies are required to define clearer breeding objectives and to systematically design a breeding program for the genetic improvement of New Zealand dairy goats.Item Gastric emptying and plasma glucose response in men following ingestion of milk from different species : thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutritional Science at Massey University, Palmerston North, New Zealand(Massey University, 2005) Schnell, Nicholas JohnThe 13 C Octanoic acid breath test (OABT) was used to measure the rate of gastric emptying of whole goat's milk (WG), whole cow's milk (WC), goat's milk infant formula (GIF) and cow's milk infant formula (CIF) in healthy, adult men. Prior to the gastric emptying study, the integrity of the vacuum in two commonly used gas collection tubes was tested. The experiment showed that the Exetainer® brand of tube was more suitable for collecting expired air compared to the Vacutainer® brand based on the fact that it had less residual dead-space which could dilute expired air samples. Fifteen healthy men were given one of the four test milks containing 100μg 13 C octanoic acid after an overnight fast. Breath samples were collected at regular intervals for four hours. Following analysis by ratio isotope mass spectrometry, gastric emptying parameters were calculated. The gastric emptying half time (t 1/2 ) of CIF was significantly shorter (P<0.05) than that of GIF (120 min vs. 159 min), but there were no differences in the rate of emptying between WC (141 min) and WG (150 min). There were no significant differences between either of the infant formulas and the whole milks. Blood samples were taken concurrently with the expired air samples. The samples were analysed to determine plasma glucose concentration. The results of showed that the timing of the peaks of plasma glucose levels and subsequent drop to below baseline concentration may be associated with the rate of gastric emptying. The manner in which the four test milks coagulated was also tested. Milks were incubated in vitro at 37.5°C after acidification with l molar HCl (to gastric pH 3) and addition of the enzyme pepsin. Vastly different coagulation properties were observed. The WC formed large curds with a clear separation between the whey-containing liquid and the curd whereas the WG and GIF were more homogenous with finer curds and considerably less clear fluid. The CIF exhibited very fine curds. Differences in composition between whole goat's milk and whole cow's milk did not appear to be sufficient to elicit different rates of gastric emptying. Thus any nutritional differences between milk from the two species may not be related to the rate at which they are emptied from the stomach.Item Goat and cow casein derived ingredients and their interactions with iron : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology, Massey University, Palmerston North, New Zealand(Massey University, 2017) Smialowska, Alice MałgorzataThe objective of this study was to gain a fundamental understanding of how goat casein micelles and the products of casein proteins behave when fortified with iron. Iron fortified skim milk was characterised by analysing the mass balance of micellar/non micellar fractions, chemical changes, micellar size changes and internal structure. Two treatments were examined to determine where in the processing line the addition of iron might best be added to a milk system. On average, at least 72% of the iron is bound to the micellar phase across the treatments and iron concentrations. Small angle X-ray scattering (SAXS) indicated that internal changes, mainly at the location of the colloidal calcium phosphate, occurred with iron addition. Casein was extracted from goat milk using isoelectric precipitation however the extraction was more difficult than using cow milk. Iron fortification of the caseinates resulted in a tendency for oxidation and precipitation of the proteins to occur causing the formation of large aggregates. The caseinates could not stabilise the same amounts of iron to that of an intact casein micelle. Phosphopeptides were isolated by adding calcium and ethanol to caseinate digests. There was an increase in serine, glutamic acid and isoleucine residues compared to caseinate. There was an increase in phosphorus from 7.8 ± 0.3 mg P/ g solids to 45.4 ± 2.4 mg P/ g solids in the isolate. The phosphopeptides were composed of smaller, more hydrophilic peptides compared to the full digest prior to precipitation. Ferrous sulfate was then investigated for use as the precipitant, instead of calcium. The peptides produced similar trends in terms of amino acid profile changes, phosphorus concentration increase and yield. Immobilised metal affinity chromatography was also investigated however this had a low throughput that may not be effective at process scale. The effect of heating, cooling, ionic strength of the solution, holding time, iron loading, processing order and use in a model milk system were investigated to simulate potential industrial processing conditions using the calcium - extracted phosphopeptides. It was found that goat peptide isolates were able to bind 54.4 ± 0.5 mg Fe/ g protein compared to goat milk of 4.3 ± 0.1 mg Fe/ g protein. The optimal conditions for binding were found to be at pH 6.7 in a low ionic strength solution, around 37 oC. There was a potential synergistic effect of adding the peptides to milk in terms of iron binding capacity. There were few differences in the amount of iron that could be bound comparing cow and goat derived phosphopeptides under the tested conditions. The oxidation potential of ingredients was determined using malondialdehyde (MDA) as an oxidation product marker. There was a reduction in oxidation when iron was bound to milk or peptides compared to free ferrous sulfate in solution with intact goat milk performing the best producing 0.46 ± 0.04 μg MDA/mL after 3 days at 30 oC compared to the blank of 1.25 ± 0.16 μg MDA/mL. The goat peptides produced non-significantly different levels of MDA compared to the blank containing no ferrous sulfate. Caco-2 cell lines are a way of approximating how systems may function in an intestine in terms of nutrient absorption. Iron absorption was improved in the order of casein hydrolysates > caseinate > skim milk for goat milk. In contrast, cow milk appeared to perform better without any modifications to the proteins. On an equal iron filtrate basis after the digestion and intestinal phase, calcium- precipitated goat phosphopeptides produced a response of 9.64 ± 0.94 ng ferritin/ nM iron. This response was greater than all other treatments with the exception of goat milk fortified with 5 mM iron and ascorbic acid with 12.30 ± 1.23 ng ferritin/ nM iron. This work covers a wide range of milk products and iron interactions and has helped to build a fundamental understanding of goat milk protein functionality. The underpinning considerations to a manufacturing setting may allow further development of large scale ingredient production for the improved stability of iron fortified systems.Item Shelf life of goat infant formula powder : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Chemical and Bioprocess Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2015) Lai, Po-HanOxidative rancidity was found to be a problem in goat milk infant formula powder. Oxidative rancidity results from the lipid oxidation processes, where oxygen reacts with unsaturated fatty acids from milk powder to produce lipid hydroperoxides and radicals, the primary oxidation products. These primary oxidation products are odourless; however, they are very reactive to breakdown into hydrocarbons, aldehydes and ketones. Aldehydes have low flavour threshold limits and are responsible for causing the rancid flavour in the milk powder. Peroxide value (PV) is one of the most widely used tests for oxidative rancidity as it is a measure of the concentration of lipid hydroperoxides; however, it is difficult to provide a specific guideline relating PV to rancidity. A reliable test is needed to determine whether the goat milk infant formula powder is unacceptable due to oxidative rancidity to the consumer. It was found that oxygen was a useful parameter to monitor lipid oxidation. Oxygen is the main reactant in lipid oxidation, and the rate of oxygen consumption is a useful tool to track lipid oxidation. Hexanal was determined to be the main secondary oxidation product responsible for the off flavour of milk powder. An experiment of accelerated storage trials for two infant formula products (Powder A and Powder B) was conducted by using a range of higher temperatures from 37°C to 57°C over a period of 12 to 24 weeks. Headspace oxygen and headspace hexanal of the milk powder in the glass vials were measured over the storage period. Sensory analysis was also conducted in parallel with the storage trial to provide a relationship between the sensory score and hexanal concentration, ultimately determining the unacceptable flavour threshold limit for hexanal concentration. The chemical kinetic constants were estimated by fitting a general nth order reaction with an Arrhenius law model with the concentration of oxygen obtained experimentally. The model followed half order reaction for both products. The Arrhenius rate constant, k0, and activation energy, E, were found to be 7.8×109 % 0.5 week-1 and 62.0 kJ mol-1 for Powder A and 1.34×107 % 0.5 week-1 and 45.60 kJ mol-1 for Powder B. It was discovered that oxygen and hexanal were highly correlated with R2 of 0.905 for Powder A and R2 of 0.918 for Powder B when fitted exponentially. It was predicted that Powder A would be unacceptable after a storage time of 40 weeks, and 31 weeks for Powder B under 25°C storage temperature. Data tables were generated to outline the different maximum storage times allowed with different storage temperatures and different initial storage oxygen concentration.Item Effects of dietary caprine milk oligosaccharides enriched fraction on maternal large intestine and the consequences for the development of the offspring : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Massey University, Palmerston North, New Zealand(Massey University, 2015) Thum, CarolineThe colonisation of the neonate gastrointestinal tract by health-promoting microbiota is likely to improve the overall health of the infant and may also have health benefits in later life. Initial development and maturation of the foetal/neonatal gastrointestinal tract is heavily influenced by the in utero environment which itself, may be altered by the maternal diet and gastrointestinal tract microbiota composition. The maternal gastrointestinal tract microbiota can be altered by supplementation with synthetic oligosaccharides; however, positive effects on the health and well-being of the offspring have not been adequately established. Human milk contains natural oligosaccharides known to improve the gastrointestinal tract colonisation and the development and maturation of the infant gastrointestinal tract. Among domestic farm animals, caprine milk has oligosaccharides structurally similar to human milk and potentially similar beneficial effects for the infant. We hypothesised that feeding caprine milk oligosaccharide enriched product to pregnant and lactating mice would induce changes in the maternal large intestine microbiota and milk composition, accelerating the development and maturation of the offspring’s large intestine tissue and altering the gastrointestinal tract microbiota composition. The aim of this project was to obtain bifidobacteria from the faeces of breast-fed human infants and determine which were of capable fermenting caprine milk oligosaccharide enriched product. Subsequently, the effects of the best strains on the morphology and metabolic pathways of the colonic mucosa of germ-free and conventionally raised mice, supplemented with dietary caprine milk oligosaccharide enriched product. The present study is the first to report New Zealand Saanen caprine colostrum, milk and whey. An enrichment method previously described was used to produce a caprine milk oligosaccharide enriched product for in vitro and in vivo assessment of its health effects. Caprine milk oligosaccharide enriched product was shown to differentially stimulate the growth of bifidobacteria, commonly found in the gastrointestinal tract of breast-fed infants. Among the bifidobacterial species tested, Bifidobacterium bifidum utilised caprine milk oligosaccharide enriched product most efficiently when compared to Bifidobacterium breve and Bifidobacterium longum subsp. longum. B. bifidum (AGR2166) was shown to ferment the sialyloligosaccharides, 3’- and 6’-sialyl-lactose present in caprine milk oligosaccharide enriched product through cell-associated sialidase expression. Augmented microbial biomass associated with enhanced growth and in vitro fermentation of caprine milk oligosaccharide enriched product, increased the production of microbial fermentation end products such as acetate and lactate. These findings indicate that in vivo caprine milk oligosaccharide enriched product may stimulate the growth and fermentation of bifidobacteria within the gastrointestinal tract. Germ-free mice or mice mono-associated with B. bifidum (AGR2166) were used to test the in vivo effects of maternal caprine milk oligosaccharide enriched product consumption during pregnancy and the effects on the foetus. Caprine milk oligosaccharide enriched product diet showed no effects on maternal gastrointestinal tract or foetal growth regardless of microbial status. Mice inoculated with B. bifidum (AGR2166) and fed caprine milk oligosaccharide enriched product diet, however, showed an increased bacterial translocation from maternal gastrointestinal tract to organs and placenta (inferred by the presence of the bifidobacteria 16S rRNA gene in the maternal organs). Increased translocation of commensal bacteria from maternal gastrointestinal tract to the foetus may have important effects on foetal immunological programming. The consumption of caprine milk oligosaccharide enriched product, during gestation and lactation were also tested in conventional rodents and it had no effects on maternal gastrointestinal tract microbiota and morphology. Changes on maternal lipid metabolism and increased maternal milk protein, however, were observed. These modifications may have positively affected the development of the pups, relative abundance of gastrointestinal tract bifidobacteria and butyric acid production at weaning. Important changes in the plasma and urine metabolites involved in bile acid and fatty acid metabolism were also observed in the pups as a consequence of maternal caprine milk oligosaccharide-enriched diet. The effects of maternal caprine milk oligosaccharide enriched product diet on pups, were no longer apparent after 30 days of consuming a control diet post-weaning, however, detrimental physiological characteristics such as an increased body fat were observed. Further studies, are needed to understand the physiological effects of caprine milk oligosaccharides on the maternal/infant pair.Item The interaction of probiotic bacteria and an oligosaccharide-enriched fraction from goat whey on in vitro intestinal barrier function and mucin production : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Massey University, Manawatu, New Zealand(Massey University, 2014) Barnett, AliciaMultiple interactions occur in the human large intestine between the host, the intestinal microbiota and fermentable carbohydrates which transit relatively intact through the small intestine. A major site at which many of these interactions occur is the intestinal epithelium, which is formed from a single layer of epithelial cells. The cellular composition of the epithelial layer in the human small and large intestine varies in respect to the numbers of absorptive enterocytes and mucus-secreting goblet cells. For the human intestine the proportion of goblet cells among epithelial cell types is thought to increase from the duodenum (4%) to the distal colon (16-24%). Epithelial cell co-culture models were developed containing absorptive enterocytes (Caco-2 cells) and mucus-secreting goblet cells (HT29-MTX cells) that more closely simulate the cell proportions found in the small (90:10) and large intestine (75:25). Trans-epithelial electrical resistance (TEER) of the co-cultures was more similar to reported values of ex vivo intestinal tissue of human small and large intestine than either of the two mono-cultures. Additionally, the mucus layer thickness present at the apical surface of 75:25 co-cultures (cellular composition representative of the large intestine) was similar to the reported thickness of the inner mucus layer of human large intestine. Introduction of an oligosaccharide-enriched fraction (OEF) from goat whey to the epithelial co-culture models was shown to modulate barrier integrity as measured by TEER, in a dose-dependent manner. Oligosaccharides (1 mg/mL) increased TEER and mucin gene/protein expression of epithelial co-cultures. Finally, the interaction between probiotic bacteria and the OEF and their individual or combined effects on intestinal epithelial barrier integrity and mucin gene/protein expression was investigated. The OEF supported the growth of selected probiotic strains, and enhanced the adhesion of defined strains to the epithelial co-cultures. When in combination with the OEF, Lactobacillus plantarum 299v enhanced TEER and mucin gene/protein expression, the increase of which was greater than that for either component alone. This suggests that an interaction between Lactobacillus plantarum 299v and the OEF exists which enhances barrier integrity through increased TEER and mucin gene/protein expression, all of which are essential components of the intestinal barrier. The research presented in this dissertation has indicated that in vitro epithelial co-cultures can be used as a model to improve our understanding of the mechanisms through which probiotic bacteria/food components and intestinal epithelial cells interact, and these key findings will assist in the development of strategies to improve intestinal barrier function using novel dietary components.Item Effect of goat milk on bone mass, morphology and biomechanics : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Anatomy and Physiology at Massey University, Palmerston North, New Zealand(Massey University, 2012) McKinnon, HilaryMilk is a major source of dietary calcium which is essential for bone growth and maintenance, and is seen as a beneficial resource in the prevention and alleviation of osteoporotic bone loss. The objectives of this thesis were to investigate the effects of a bioactive component of goat milk, Casein phosphopeptide (CPP), and its ability to increase calcium solubility for improved calcium absorption and retention. To investigate the effect of a formulated goat milk diet as a nutritional supplement on bone growth and mineral accretion; and to investigate the effect of the long term consumption of goat milk as a nutritional supplement with or without a drug therapy (Sodium Alendronate) to determine any complementary effects on ovariectomy induced osteoporosis in the female rat. The effect of CPP on calcium bioavailability was investigated in growing rats during a period of rapid bone growth. The diets that contained 80% and 57% of goat milk protein as casein delivered increased calcium absorption compared to the diet containing 17% casein, suggesting a minimum level of casein is needed to optimise calcium absorption from goat milk. However, increased calcium absorption did not result in increased mineral retention in the femur or lumbar spine. The next trial had two animal experiments with a total of 200 rats involved (Chapter 4 and 5); in the first experiment all 200 rats were fed either a non-milk diet, a formulated cow’s milk diet, or a formulated goat milk diet from 3 weeks of age until 5 months of age. At its conclusion 60 rats were euthanized and ex vivo samples taken for analysis. The second experiment saw the remaining mature rats either ovariectomized or sham operated then grown until 10 months. The consumption of the goat milk diet increased mineral accretion during the phase of rapid bone growth beyond ‘Peak bone mass’ at approximately 12 weeks of age until maturity at 5 months of age. Mineral retention in the femoral shaft showed that the rats fed the goats milk diet had significantly greater quantities of mineral (p<0.001) compared to the not-milk group. Investigation of the marrow cavity showed that bone formation at the two cross sections examined at the femoral mid-shaft were more significant for the rats fed the goat milk diet compared to the rats fed the non-milk diet (p<0.034 and p<0.007) respectively. Ovariectomy surgery at 5½ months caused osteoporotic like conditions in bone to develop resulting in the rapid loss of bone mass in the ovariectomized rats. This saw both periosteal and endosteal expansion resulting in larger overall marrow cavities (p<0.0001) in the femoral shaft and larger overall cross sectional area (p<0.002). Ovariectomy was also found to have an uneven effect on bone loss within the femoral shaft of ovariectomized rats (OVX), where bone at the endosteal surface had a tendency to be lost at a greater rate than the distal region compared to sham operated rats (SHAM) (p<0.061). This regional change showed that the SHAM rats had relatively larger bone areas in the proximal region, whereas, OVX rats had relatively larger bone areas in the distal region (p<0.0005). Dual energy x-ray absorptiometry (DEXA) measurements of the lumbar spine and femur did not show any significant differences between OVX and ovariectomized alendronate groups (OVX ALD) fed either of the milk diets (Chapter 5). However, there was a potentially differing, almost opposite effect within each of the two milk diets in the bone area of the femoral shaft. The GOAT OVX rats showed a trend for larger overall mean bone areas than the GOAT OVX ALD rats (p<0.063), yet in contrast to this the COW OVX rats showed a trend for smaller overall mean bone areas than the COW OVX ALD rats in the femoral shaft although not significant. The rats fed a long term diet of formulated goat milk and dosed with alendronate had a tendency to have tougher bone material per unit of bone (J/mm2) than rats fed cow’s milk and dosed with alendronate (p<0.073) in the femoral mid-shaft. Whereas, in the proximal femoral shaft the rats fed either of the milk diets and dosed with alendronate had tougher bone material per unit of bone (J/mm2) than the rats fed either of the milk diets and dosed with the placebo (p<0.05). Analysis of the trabecular structure of the proximal tibia showed that the rats fed goats milk and dosed with alendronate increased the prevalence of rod shaped trabeculae (p<0.048), increased surface volume to bone ratio (p<0.001), reduced the connectivity between trabeculae struts within the structure (p<0.004), decreased the fractal dimensions of the trabecular structure (p<0.018), and had thinner trabeculae (p<0.006) compared to the rats fed the Goat milk diet and dosed with the placebo. In conclusion, this thesis has found that the long-term consumption of goat milk may provide some protection against ovariectomy bone loss in rats. This may be in part due to increased mineral accretion during the phase of rapid bone growth. The co-administration of goat milk and alendronate had a significant effect on the toughness of the bone material per unit area of bone in the proximal and mid-shaft of the femur, however, potentially weakened the trabecular structure of the proximal tibia.