Production performance, milk composition and cheese quality of crossbred dairy sheep supplemented with dietary omega-3 oils By Quang Vu NGUYEN BAnimSci, MAgSci (Thai Nguyen University of Agriculture and Forestry) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy College of Public Health, Medical and Veterinary Sciences James Cook University, Townsville, Queensland, Australia July 2019 i Declaration I hereby declare that: The research presented and reported in this thesis was conducted in accordance with the University of Tasmania Animal Ethics Committee Guidelines, the 1993 Tasmanian Animal Welfare Act and the 2004 Australian Code of Practice for the Care and Use of Animals for Scientific Purposes (Animal Ethics Permit Number A0015657). To the best of my knowledge and belief, this thesis contains no material which has been accepted for the award of a degree or diploma by the University or any other tertiary institution. The thesis contains no material previously published or written by any other person (s) except where background information duly acknowledged is made in the text of the thesis. ii Statement of the Contribution of Others Financial Support Australian Awards PhD Scholarship, Department of Foreign Affairs and Trade of the Australian Commonwealth Government.
College of Public Health, Medical and Veterinary Sciences, James Cook University. Supervision Associate Professor Aduli Malau-Aduli Adjunct Professor Peter Nichols Associate Professor Bunmi Malau-Aduli Associate Professor John Cavalieri Analytical and Statistical Support Associate Professor Aduli Malau-Aduli Adjunct Professor Peter Nichols Dr. John Otto Editorial Support Associate Professor Aduli Malau-Aduli Adjunct Professor Peter Nichols Associate Professor Bunmi Malau-Aduli Associate Professor John Cavalieri iii Acknowledgements I would like to thank a number of individuals who helped me to successfully complete this degree. First of all, my sincere gratitude goes to A/Prof Aduli Malau-Aduli, Prof Peter D.
Nichols, A/Prof Bunmi Malau-Aduli and A/Prof John Cavalieri, for their guidance, knowledge and support as my advisors. I would like to pay special thanks to my Primary Advisor, A/Prof Aduli Malau-Aduli, who patiently and unconditionally supported and encouraged me to pursue the Australia Awards Scholarship programme and also throughout the course of my PhD research. I would also like to thank my fellow PhD students, postdoctoral mentors and laboratory personnel: John Otto, Aaron Flakemore, Nguyen Viet Don, Le Van Hung, Peter Mansour, Peter Nish, and Patti Virtue for their generous assistance during the feeding trial and lab work. I am grateful to all staff of TasHerd Pty Ltd (Hadspen, Tasmania), CSIRO Oceans and Atmosphere Laboratory (Hobart, Australia), and Central Science Laboratory, University of Tasmania (Hobart, Australia) for chemical and fatty acid analyses.
I acknowledge CopRice Feeds, Cobden, Victoria, Australia, for producing the experimental pellets to specification. Appreciation also goes to Diane Rae, Nicole Gilliver, Ryan Hartshorn and all staff of Grandvewe Cheeses Farm, Birchs Bay, Woodbridge, Tasmania, Australia, for supplying experimental animals, milking and other facilities for this research project. In addition, I am thankful to Australia Awards Scholarship from the Australian Commonwealth Department of Foreign Affairs and Trade, Canberra ACT, and to the College of Public Health, Medical and Veterinary Sciences, James Cook University Townsville, Queensland, Australia, for financial support throughout my PhD program. Very special thanks to my parents, lovely wife Tran Thi Le Na, gorgeous son Nguyen Vu Khanh, brothers, sisters, nieces and nephews for their encouragement and support throughout my life.
iv Abstract This thesis primarily investigated the effect of supplementing pasture-based dairy sheep with different plant oil-infused and rumen-protected pellets containing eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3)on lactation performance, milk and cheese fatty acid composition and cheese eating quality. It was hypothesised that plant oil supplements would interact with sire breed to influence feed intake, body condition score, milk yield and composition, milk and cheese fatty acid contents and sensory attributes of ripened cheese. Sixty dairy ewes in mid-lactation, balanced by liveweight, milk yield, parity, and sire breed were randomly allocated into 6 treatment groups of 10 ewes each, that were: (1) supplemented with on-farm existing commercial wheat-based pellets without oil inclusion (control) or supplemented with wheat-based pellets infused with 50 mL/kg dry matter of oils from (2) canola, (3) rice bran, (4) flaxseed, (5) safflower, and (6) rumen-protected EPA + DHA in a 10- week supplementary feeding trial including a 2-week adjustment period. All supplementary diets included the same level of 50 mL/kg DM of oil except for the control group, and all diets were isocaloric and isonitrogenous.
Experimental animals were grazed in the same paddock with ad libitum access to pasture, hay, and water. During milking time, each ewe was fed 1 kg/day of the supplemented pellets individually in the milking parlour. Data on weekly body condition score, daily feed intake, feed composition, weekly bulked fresh milk, raw milk, and ripened cheese samples were collected. Feed intake, body condition score, milk yield, milk composition, fatty acid composition of milk and cheese, and cheese sensory attributes were analysed in SAS with sire breed, diet, and week of supplementation and their second-order interactions as fixed effects.
It was demonstrated that oil supplementation and sire breed affected animal performance, productivity and quality of milk and its processed product, in that: v 1) Rumen-protected oil pellet containing EPA + DHA was the most effective diet that improved milk production, n-3 long-chain (C≥20) polyunsaturated fatty acids (n-3 LC-PUFA) in fresh milk and ripened cheese without any negative effect on animal performance and cheese eating quality. A serving of milk and cheese reached the “good source” and “source” levels of n-3 LC-PUFA, respectively; 2) Flaxseed oil supplementation elicited not only the highest concentration of α- linolenic acid (ALA, 18:3n-3) in both fresh milk and ripened cheese, but also improved all cheese eating sensory traits. Flaxseed oil also significantly increased n-3 LC-PUFA in milk because a serving of fresh milk met the claimed “source” of n-3 LC-PUFA; 3) Safflower oil diet considerably improved milk, fat and protein yields. More importantly, this diet also had the most efficiency at enhancing the level of linoleic acid (18:2n-6) in milk and cheese.
Safflower oil inclusion had no effect on cheese eating quality; 4) Rice bran oil was the sole diet that improved milk yield with an increase in protein content. However, adding rice bran oil to the diet of grazing dairy ewes had only minor effects on altering milk and cheese PUFA composition. Together with flaxseed oil, rice bran oil significantly enhanced consumer acceptability of ripened cheese; 5) Canola oil was found to have minor but statistically significant effect on milk yield, body condition score, and docosapentaenoic acid (DPA, 22:5n-3) content in milk; 6) Sire breed and its interaction with diet affected milk yield in crossbred Awassi x East Friesian ewes. Taken together, these outcomes suggest the use of infused plant oil and rumen-protected oil supplements in crossbred Awassi x East Friesian to best optimise overall milk and cheese quality and productivity of dairy sheep under a typical on-farm Australian grazing system.
vi Thesis Publications Peer-reviewed Journal Papers with 2017 Impact Factor (IF) 1. Nguyen QV, Malau-Aduli BS, Cavalieri J, Nichols PD, Malau-Aduli AEO 2019. Enhancing omega-3 long-chain polyunsaturated fatty acid content of dairy-derived foods for human consumption. Nguyen QV, Le HV, Nguyen DV, Malau-Aduli BS, Nichols PD, Malau-Aduli AEO 2019.
Enhancement of dairy sheep cheese eating quality with increased omega-3 long-chain polyunsaturated fatty acids. Journal of Dairy Science 102(1): 211-222 (IF 2. Nguyen QV, Le VH, Nguyen DV, Malau-Aduli BS, Nichols PD, Malau-Aduli AEO 2018. Supplementing grazing dairy ewes with oil and rumen‐protected EPA+DHA pellets enhances health‐beneficial n‐3 long‐chain polyunsaturated fatty acids in sheep milk.
European Journal of Lipid Science and Technology 120 (6): 1700256 (IF 2. Nguyen QV, Le HV, Nguyen DV, Nish P, Otto JR, Malau-Aduli BS, Nichols PD, Malau-Aduli AEO 2018. Supplementing dairy ewes grazing low quality pastures with plant-derived and rumen-protected oils containing Eicosapentaenoic Acid and Docosahexaenoic Acid pellets increases body condition score and milk, fat, and protein yields.3390/ani8120241 vii Table of Contents Declaration. ii Statement of the Contribution of Others.
vii Table of Contents. viii List of Tables. xi List of Figures. xiii List of Abbreviations.
xiv Chapter 1: General Introduction. 1 Chapter 2: Literature Review. Dairy sheep industry background. Factors affecting milk yield and composition.
Body condition score as an essential management tool for dairy sheep producers. Enhancing omega-3 long-chain polyunsaturated fatty acid content of dairy-derived foods for human consumption. Role of Omega 3 long chain polyunsaturated fatty acid. Structure of omega-3 LC-PUFA.
Metabolic pathways, human health benefits and recommended intake of n-3 PUFA. Lipid metabolism in ruminants: Obstacles to enriching milk fat with n-3 PUFA. Recent attempts to increase n-3 PUFA content in dairy-derived products. Nutritional aspect of sheep cheese and factors driving cheese eating quality.
Nutritional aspects of sheep cheese. Factors driving cheese eating quality. Justification and Research Objectives of the study. 46 viii Chapter 3: Supplementing dairy ewes grazing low quality pastures with plant-derived and rumen-protected oils containing EPA + DHA pellets increases body condition score and milk, fat, and protein yields.
Materials and Methods. Animal Management and Experimental Design. Feed intake and body condition score. Milk sample analyses.
Chemical analysis of experimental and basal diets. Data and statistical analysis. Effect of dietary supplements on dry matter intake and body condition score. Effect of dietary supplements on milk yield, and milk composition.
Effect of breed on animal performance. 65 Chapter 4: Supplementing grazing dairy ewes with plant-derived oil and rumen- protected EPA+DHA enhances health – beneficial n-3 long-chain polyunsaturated fatty acids in sheep milk. Materials and ethods. Animal management and experimental design.
Chemical analysis of experimental feeds. Milk sample collection and fatty acid analysis. 83 ix Chapter 5: Enhancement of dairy sheep cheese eating quality with increased n-3 long- chain polyunsaturated fatty acids. Materials and methods.
Animals and treatments. Chemical analysis of experimental feeds. Fatty acid analysis. Calculation of cheese FA recovery.
Consumer sensory evaluation. FA composition and recovery of the main n-6 and n-3 LC-PUFA in ripened cheese. Concentration of the main n-6 and n-3 LC-PUFA per standard serve of cheese and cheese sensory test. Effect of oil supplementations on the proportion of beneficial PUFA in ripened cheese.
Effect of oil supplementations on the recovery of LC-PUFA of ripened cheese. Effect of oil supplementations on the absolute concentration of LC-PUFA and eating quality of ripened cheese. 104 Chapter 6: General Discussion and Conclusion. 142 x List of Tables Table 2.
Worldwide sheep milk products (Source: FAOSTA (2018). Mineral and vitamin contents in sheep, goat and cow milk (Sources: Park et al., 2007; Balthazar et al. Average lactation length, milk yield and composition of common sheep breeds used for milk production (Sources: Haenlein, 2007; Park et al. Heritabilities and genetic correlations for lactating traits of different breeds (Source: Park et al.
Effect of lipid supplementation on milk yield and compositiona. Description of body condition scoring of sheep (Source: Western Australian Department of Agriculture). Common food sources of ALA (18:3n-3, as gram per serving). Content of n-3 LC-PUFA in common seafood and other animal sources.
Effect of pasture feeding regimes on n-3 PUFA content of milk (g/100g fatty acids). Effect of supplementing ruminants with plant-derived dietary sources on n-3 PUFA concentration in milk and milk products (g/100g fatty acids). Effect of supplementing ruminants with dietary marine sources on n-3 PUFA concentration of milk and milk products (g/100g fatty acids). Heritability estimates of major individual and group of n-3 fatty acids.
Major nutritional properties of sheep cheese (%) (Source: Raynal-Ljutovac et al. Ingredient composition of the experimental pellets. Nutrient compositionsa of basal and experimental diets. Least square means and standard errors (LSM ±SEM) of experimental feed intake (g/head/day).
Effect of supplementation with diverse plant-derived oils on body condition score and lactation performance traits. Nutrient composition of experimental diets.