Nutrient Prioritization in Dairy Cows Early Postpartum: Mismatch Between Metabolism and Fertility?

Reproduction in Domestic Animals

Volumn 43, Issue SUPPL.2, 2008, Pages 96-103

  Leroy, J L M R ^a   Vanholder, T ^a   Van Knegsel, A T M ^b   Garcia Ispierto, I ^c   Bols, P E J ^a  

^a Veterinary Centre Someren   (Netherlands)

^b WAGENINGEN UNIVERSITY   (Netherlands)

^c UNIVERSITAT AUTÒNOMA DE BARCELONA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ANIMAL; ANIMAL FOOD; BREEDING; CATTLE; DAIRYING; ENERGY METABOLISM; FEMALE; FERTILITY; GENETICS; LACTATION; METHODOLOGY; NUTRITIONAL REQUIREMENT; PHYSIOLOGY; PREGNANCY; PUERPERIUM; REPRODUCTION; REVIEW;

ANIMAL FEED; ANIMAL NUTRITIONAL PHYSIOLOGICAL PHENOMENA; ANIMALS; BREEDING; CATTLE; DAIRYING; ENERGY METABOLISM; FEMALE; FERTILITY; LACTATION; NUTRITIONAL REQUIREMENTS; POSTPARTUM PERIOD; PREGNANCY; REPRODUCTION;

EID: 58149203494     PISSN: 09366768     EISSN: 14390531     Source Type: Journal    
DOI: 10.1111/j.1439-0531.2008.01148.x     Document Type: Article

References (112)

1. Amstalden M, Harms PG, Welsh TH Jr, Randel RD, Williams GL, 2005: Effects of leptin on gonadotropin-releasing hormone release from hypothalamic-infundibular explants and gonadotropin release from adenohypophyseal primary cell cultures: further evidence that fully nourished cattle are resistant to leptin. Anim Reprod Sci 85, 41-52.
2. Armstrong DG, Baxter G, Hogg CO, Woad KJ, 2002a: Insulin-like growth factor (IGF) system in the oocyte and somatic cells of bovine preantral follicles. Reproduction 123, 789-797.
3. Beam SW, Butler WR, 1997: Energy balance and ovarian follicle development prior to first ovulation postpartum in dairy cows receiving three levels of dietary fat. Biol Reprod 56, 133-142.
4. Beam SW, Butler WR, 1999: Effects of energy balance on follicular development and first ovulation in postpartum dairy cows. J Reprod Fertil Suppl 54, 411-424.
5. Bilodeau-Goeseels S, 2006: Effect of culture media and energy sources on the inhibition of nuclear maturation in bovine oocytes. Theriogenology 66, 297-306.
6. Bilodeau-Goeseels S, Kastelic JP, 2003: Factors affecting embryo survival and strategies to reduce embryonic mortality in cattle. Can J Anim Sci 83, 659-671.
7. Bilodeau-Goeseels S, Panich P, 2002: Effects of quality on development and transcriptional activity in early bovine embryos. Anim Reprod Sci 71, 143-155.
8. Blache D, Zhang S, Martin GB, 2006: Dynamic and integrative aspects of the regulation of reproduction by metabolic status in male sheep. Reprod Nutr Dev 46, 379-390.
9. Blache D, Chagas LM, Martin GB, 2007: Nutritional inputs into the reproductive neuroendocrine control system - a multidimensional perspective. Reproduction, Supplement 64, 124-139.
10. Boland MP, Lonergan P, O'Callaghan D, 2001: Effect of nutrition on endocrine parameters, ovarian physiology, and oocyte and embryo development. Theriogenology 55, 1323-1340.
11. Bols PEJ, Ysebaert MT, Lein A, Coryn M, Van Soom A, De Kruif A, 1998: Effects of long-term treatment with bovine somatotropin on follicular dynamics and subsequent oocyte and blastocyst yield in an OPU-IVF program. Theriogenology 49, 983-995.
12. Bossaert P, Leroy JLMR, Cools S, Opsomer G, 2007: Impact of metabolic and endocrine parameters on ovulation in high-yielding dairy cows (abstract). Reprod Domest Anim 42, 118.
13. Bousquet D, Bouchard E, Du Tremblay D, 2004: Decreasing fertility in dairy cows: myth or reality? Le Médecin Vétérinaire 34, 59-61.
14. Britt JH, 1992: Impacts of early postpartum metabolism on follicular development and fertility. Proc Annu Convention Am Assoc Bovine Pract 24, 39-43.
15. Butler WR, 2001: Nutritional effects on resumption of ovarian cyclicity and conception rate in postpartum dairy cows. Anim Sci Occas Publ 26, 133-145.
16. Butler WR, 2003: Energy balance relationships with follicular development, ovulation and fertility in pp dairy cows. Livestock Prod Sci 83, 211-218.
17. Butler ST, Marr AL, Pelton SH, Radcliff RP, Lucy MC, Butler WR, 2003: Insulin restores GH responsiveness during lactation-induced negative energy balance in dairy cattle: effects on expression of IGF-I and GH receptor 1A. J Endocrinol 176, 205-217.
18. Butler ST, Pelton SH, Butler WR, 2004: Insulin increases 17β-estradiol production by the dominant follicle of the first postpartum follicle wave in dairy cows. Reproduction 127, 537-545.
19. Castaneda-Gutierrez E, Overton TR, Butler WR, Bauman DE, 2005: Dietary supplements of two doses of calcium salts of conjugated linoleic acid during the transition period and early lactation. J Dairy Sci 88, 1078-1089.
20. Chagas LM, Bass JJ, Blache D, Burke CR, Kay JK, Lindsay DR, Lucy MC, Martin GB, Meier S, Rhodes FM, Roche JR, Thatcher WW, Webb R, 2007: New perspectives on the roles of nutrition and metabolic priorities in the subfertility of high-producing dairy cows. J Dairy Sci 90, 4022-4032.
21. Cnop M, Hannaert JC, Hoorens A, Eizirik DL, Pipeleers DG, 2001: Inverse relationship between cytotoxicity of free fatty acids in pancreatic islet cells and cellular triglyceride accumulation. Diabetes 50, 1771-1777.
22. Coffey MP, Simm G, Oldham JD, Hill WG, Brotherstone S, 2004: Genotype and diet effects on energy balance in the first three lactations of dairy cows. J Dairy Sci 87, 4318-4326.
23. De Wit AAC, Cesar MLF, Kruip TAM, 2001: Effect of urea during in vitro maturation on nuclear maturation and embryo development of bovine cumulus-oocyte-complexes. J Dairy Sci 84, 1800-1804.
24. Diskin MG, Mackey DR, Roche JF, Sreenan JM, 2003: Effects of nutrition and metabolic status on circulating hormones and ovarian follicle development in cattle. Anim Reprod Sci 78, 345-370.
25. Drew B, 1999: Practical nutrition and management of heifers and high yielding dairy cows for optimal fertility. Cattle Pract 7, 243-248.
26. Dunne LD, Diskin MG, Boland MP, O'Farrell KJ, Sreenan JM, 1999: The effect of pre- and post-insemination plane of nutrition on embryo survival in beef heifers. Anim Sci 69, 411-417.
27. Garcia-Ispierto I, Lopez-Gatius F, Bech-Sabat G, Santolaria P, Yaniz JL, Nogareda C, De Rensis F, Lopez-Bejar M, 2007: Climate factors affecting conception rate of high producing dairy cows in north-eastern Spain. Theriogenology 67, 1379-1385.
28. Garnsworthy PC, Topps JH, 1982: The effect of body condition score at calving on their food intake and performance when given complete diets. Anim Prod 35, 113-119.
29. Gong JG, 2002: Influence of metabolic hormones and nutrition on ovarian follicle development in cattle: practical implications. Domest Anim Endocrinol 23, 229-241.
30. Grohn YT, Rajala-Schultz PJ, 2000: Epidemiology of reproductive performance in dairy cows. Anim Reprod Sci 60, 605-614.
31. Grummer RR, 2007: Strategies to improve fertility of high yielding dairy farms: management of the dry period. Theriogenology 68, S281-S288.
32. Gumen A, Rastani RR, Grummer RR, Wiltbank MC, 2005: Reduced dry periods and varying prepartum diets alter postpartum ovulation and reproductive measures. J Dairy Sci 88, 2401-2411.
33. Gutierrez-Aguilar CG, 1997: The effect of nutrition and metabolic hormones on follicular development in cattle. PhD Dissertation, University of Edinburgh, pp. 146-166.
34. Herdt TH, 2000: Ruminant adaptation to negative energy balance. Vet Clin North Am Food Anim Pract 16, 215-230.
35. Huirne RBM, Saatkamp HW, Bergevoet RHM, 2002: Economic analysis of common health problems in dairy cattle. In: Kaske M, Scholz H, Höltershinken M(eds), Twelfth World Buiatrics Congress, Hannover, Germany, 18-23 August 2002, pp. 420-431.
36. Ichimaru T, Mori Y, Okamura H, 2001: A possible role of neuropeptide Y as a mediator of undernutrition to the hypothalamic gonadotropin-releasing hormone pulse generator in goats. Endocrinology 142, 2389-2498.
37. Kacsoh B, 2000: Endocrine Physiology. McGraw Hill Book Co., New York, NY.
38. Kawashima C, Fukihara S, Maeda M, Kaneko E, Montoya CA, Matsui M, Shimizu T, Matsunaga N, Kida K, Miyake Y, Schams D, Miyamoto A, 2007: Relationship between metabolic hormones and ovulation of dominant follicle during the first follicular wave post-partum in high-producing dairy cows. Reproduction 133, 155-163.
39. Kenny DA, Humpherson PG, Leese HJ, Morris DG, Tomos AD, Diskin MG, Sreenan JM, 2002: Effect of elevated systemic concentrations of ammonia and urea on the metabolite and ionic composition of oviductal fluid in cattle. Biol Reprod 66, 1797-1804.
40. Kruip TAM, Kemp B, 1999: Voeding en vruchtbaarheid bij landbouwhuisdieren. Tijdschr Diergeneeskd 124, 462-467.
41. Landau S, Braw-Tal R, Kaim M, Bor A, Bruckental I, 2000: Preovulatory follicular status and diet affect the insulin and glucose content of follicles in high-yielding dairy cows. Anim Reprod Sci 64, 181-197.
42. Lequarre AS, Vigneron C, Ribaucour F, Holm P, Donnay I, Dalbies-Tran R, Callesen H, Mermillod P, 2005: Influence of antral follicle size on oocyte characteristics and embryo development in the bovine. Theriogenology 63, 841-859.
43. Leroy JLMR, Vanholder T, Delange JR, Opsomer G, Van Soom A, Bols PEJ, Dewulf J, De Kruif A, 2004: Metabolic changes in follicular fluid of the dominant follicle in high-yielding dairy cows early post partum. Theriogenology 62, 1131-1143.
44. Leroy JLMR, Opsomer G, De Vliegher S, Vanholder T, Goossens L, Geldhof A, Bols PEJ, De Kruif A, Van Soom A, 2005a: Comparison of embryo quality in high-yielding dairy cows, in dairy heifers and in beef cows. Theriogenology 64, 2022-2036.
45. Leroy JLMR, Vanholder T, Mateusen B, Christophe A, Opsomer G, De Kruif A, Genicot G, Van Soom A, 2005b: Non-esterified fatty acids in follicular fluid of dairy cows and their effect on developmental capacity of bovine oocytes in vitro. Reproduction 130, 485-495.
46. Leroy JLMR, Vanholder T, Opsomer G, Van Soom A, De Kruif A, 2006: The in vitro development of bovine oocytes after maturation in glucose and beta-hydroxybutyrate concentrations associated with negative energy balance in dairy cows. Reprod Domest Anim 41, 119-123.
47. Leroy JLMR, Opsomer G, Van Soom A, Goovaerts IGF, Bols PEJ, 2007: Reduced fertility in high yielding dairy cows: are the oocyte and embryo in danger? Part I: The importance of negative energy balance and altered corpus luteum function to the reduction of oocyte and embryo quality in high yielding dairy cows (review). Reprod Domest Anim, in press. DOI:DOI: 10.1111/j.1439-0531.2007.00960.
48. Liefers SC, Veerkamp RF, Te Pas MFW, Delavaud C, Chilliard Y, Van Der Lende T, 2003: Leptin concentrations in relation to energy balance, milk yield, intake, live weight and estrus in dairy cows. J Dairy Sci 86, 799-807.
49. Lopez H, Satter LD, Wiltbank MC, 2004: Relationship between level of milk production and oestrus behavior of lactating dairy cows. Anim Reprod Sci 81, 209-223.
50. Lozano JM, Lonergan P, Boland MP, O'Callaghan D, 2003: Influence of nutrition on the effectiveness of superovulation programmes in ewes: effect on oocyte quality and post-fertilization development. Reproduction 125, 543-553.
51. Lucy MC, 2001: Reproductive loss in high-producing dairy cattle: where will it end? J Dairy Sci 84, 1277-1293.
52. Lucy MC, 2003: Mechanisms linking nutrition and reproduction in postpartum cows. Reprod Suppl. 61, 415-427.
53. Lucy MC, 2007: Fertility in high-producing dairy cows: reasons for decline and corrective strategies for sustainable improvement. Reprod Suppl. 64, 237-254.
54. Maedler K, Spinas GA, Dyntar D, Moritz W, Kaiser N, Donath MY, 2001: Distinct effects of saturated and monounsaturated fatty acids on beta-cell turnover and function. Diabetes 50, 69-76.
55. Mallard BA, Dekkers JC, Ireland MJ, Leslie KE, Sharif S, Vankampen CL, Wagter L, Wilkie BN, 1998: Alteration in immune responsiveness during the peripartum period and its ramification on dairy cow and calf health. J Dairy Sci 81, 585-595.
56. Mann GE, Lamming GE, 2001: Relationship between maternal endocrine environment, early embryo development and inhibition of the luteolytic mechanism in cows. Reproduction 121, 175-180.
57. McEvoy TG, Robinson JJ, Aitken RP, Findlay PA, Palmer RM, Robertson IS, 1995: Dietary-induced suppression of pre-ovulatory progesterone concentrations in superovulated ewes impairs the subsequent in vivo and in vitro development of their ova. Anim Reprod Sci 39, 89-107.
58. McEvoy TG, Robinson JJ, Ashworth CJ, Rooke JA, Sinclair KD, 2001: Feed and forage toxicants affecting embryo survival and fetal development. Theriogenology 55, 113-129.
59. Nishimoto H, Matsutani R, Yamamoto S, Takahashi T, Hayashi KG, Miyamoto A, Hamano S, Tetsuka M, 2006: Gene expression of glucose transporter (GLUT) 1, 3 and 4 in bovine follicle and corpus luteum. J Endocrinol 188, 111-119.
60. O'Callaghan D, Boland MP, 1999: Nutritional effects on ovulation, embryo development and the establishment of pregnancy in ruminants. Anim Sci 68, 299-314.
61. Ohkura S, Ichimaru T, Itoh F, Matsuyama S, Okamura H, 2004: Further evidence for the role of glucose as a metabolic regulator of hypothalamic gonadotropin-releasing hormone pulse generator activity in goats. Endocrinology 145, 3239-3246.
62. Opsomer G, Coryn M, Deluyker H, De Kruif A, 1998: An analysis of ovarian dysfunction in high yielding dairy cows after calving based on progesterone profiles. Reprod Domest Anim 33, 193-204.
63. Ortega HH, Palomar MM, Acosta JC, Salvetti NR, Dallard BE, Lorente JA, Barbeito CG, Gimeno EJ, 2008: Insulin-like growth factor I in sera, ovarian follicles and follicular fluid of cows with spontaneous or induced cystic ovarian disease. Res Vet Sci 84, 419-427.
64. Overton TR, Waldron MR, 2004: Nutrtional management of transition dairy cows: strategies to optimize metabolic health. J Dairy Sci 87, E105-E119.
65. Patton J, Kenny DA, Mee JF, O'Mara FP, Wathes DC, Cook M, Murphy JJ, 2006: Effect of milking frequency and diet on milk production, energy balance and reproduction in dairy cows. J Dairy Sci 89, 1478-1487.
66. Paula-Lopes FF, Al-Katanani YM, Majewski AC, McDowell LR, Hansen PJ, 2003: Manipulation of antioxidant status fails to improve fertility of lactating cows or survival of heat-shocked embryos. J Dairy Sci 86, 2343-2351.
67. Pfaff D, 2005: Hormone-driven mechanisms in the central nervous system facilitate the analysis of mammalian behaviours. J Endocrinol 184, 447-453.
68. Pires JAA, Souza AH, Grummer RR, 2007: Induction of hyperlipidemia by intravenous infusion of Tallow emulsion causes insulin resistance in Holstein cows. J Dairy Sci 90, 2735-2744.
69. Rastani RR, Grummer RR, Bertics SJ, Gumen A, Wiltbank MC, Mashek DG, Schwab MC, 2005: Reducing dry period length to simplify feeding transition cows: milk production, energy balance, and metabolic profiles. J Dairy Sci 88, 1004-1014.
70. Rhoads ML, Rhoads RP, Gilbert RO, Toole R, Butler WR, 2006: Detrimental effects of high plasma urea nitrogen levels on viability of embryos from lactating dairy cows. Anim Reprod Sci 91, 1-10.
71. Rivera RM, Hansen PJ, 2001: Development of cultured bovine embryos after exposure to high temperatures in the physiological range. Reproduction 121, 107-115.
72. Roche JF, 2006: The effect of nutritional management of the dairy cow on reproductive efficiency. Anim Reprod Sci 96, 282-296.
73. Roche JR, Berry DP, Kolver ES, 2006: Holstein-Friesian strains and feed effects on milk production, bodyweight and body condition score profiles in grazing dairy cows. J Dairy Sci 89, 3532-3543.
74. Roche JR, Macdonald KA, Burke CR, Lee JM, Berry DP, 2007: Associations among body condition score, body weight and reproductive performance in seasonal-calving dairy cattle. J Dairy Sci 90, 376-391.
75. Roth Z, Meweidan R, Shaham-Albalancy A, Braw-Tal R, Wolfenson D, 2001a: Delayed effect of heat stress on steroid production in medium-size and preovulatory bovine follicles. Reproduction 121, 745-751.
76. Roth Z, Arav A, Bor A, Zeron Y, Braw-Tal R, Wolfenson D, 2001b: Improvement of quality of oocytes collected in the autumn by enhanced removal of impaired follicles from previously heat-stressed cows. Reproduction 122, 737-744.
77. Royal M, Mann GE, Flint APF, 2000: Strategies for reversing the trend towards subfertility in dairy cattle. Vet J 160, 53-60.
78. Sangsritavong S, Combs DK, Sartori R, Armentano LE, Wiltbank MC, 2002: High feed intake increase liver blood flow and metabolism of progesterone and estradiol-17β in dairy cattle. J Dairy Sci 85, 2831-2842.
79. Santos JEP, Thatcher WW, Chebel RC, Cerri RLA, Galvao KN, 2004a: The effect of embryonic death rates in cattle on the efficacity of estrus synchronization programs. Anim Reprod Sci 82/83, 513-535.
80. Santos JE, Cerri RL, Ballou MA, Higginbotham GE, Kirk JH, 2004b: Effect of timing of first clinical mastitis occurrence on lactational and reproductive performance of Holstein dairy cows. Anim Reprod Sci 80, 31-45.
81. Sartori R, Sartor-Bergfelt R, Mertens SA, Guenther JN, Parrish JJ, Wiltbank MC, 2002: Fertilization and early embryonic development in heifers and lactating cows in summer and lactating and dry cows in winter. J Dairy Sci 85, 2803-2812.
82. Sartori R, Haughian JM, Shaver RD, Rosa GJM, Wiltbank MC, 2004: Comparison of ovarian function and circulating steroids in estrous cycles of Holstein heifers and lactating cows. J Dairy Sci 87, 905-920.
83. Silvia WJ, 2003: Addressing the decline in reproductive performance of lactating dairy cows: a researcher's perspective. Vet Sci Tomorrow 3, 1-5.
84. Sinclair KD, Kuran M, Gebbie FE, Webb R, McEvoy TG, 2000: Nitrogen metabolism and fertility in cattle: II. Development of oocytes recovered from heifers offered diets differing in their rate of nitrogen release in the rumen. J Anim Sci 78, 2670-2680.
85. Snijders SE, Dillon P, O'Callaghan D, Boland MP, 2000: Effect of genetic merit, milk yield, body condition and lactation number on in vitro oocyte development in dairy cows. Theriogenology 53, 981-989.
86. Spicer LJ, Echternkamp SE, 1995: The ovarian insulin and insulin-like growth factor system with an emphasis on domestic animals. Domest Anim Endocrinol 12, 223-245.
87. Spicer LJ, Francisco CC, 1997: The adipose obese gene product, leptin: evidence of a direct inhibitory role in ovarian function. Endocrinology 138, 3374-3379.
88. Spicer LJ, Francisco CC, 1998: Adipose obese gene product, leptin, inhibits bovine ovarian thecal cell steroidogenesis. Biol Reprod 58, 207-212.
89. Spicer LJ, Chamberlain CS, Francisco CC, 2000: Ovarian action of leptin: effects on insulin-like growth factor-I-stimulated function of granulosa and thecal cells. Endocr 12, 53-59.
90. Sutton ML, Gilchrist RB, Thompson JG, 2003: Effects of in vivo and in vitro environments on the metabolism of the cumulus-oocyte complex and its influence on oocyte developmental capacity. Hum Reprod Update 9, 35-48.
91. Tamminga S, Luteijn PA, Meijer RGM, 1997: Changes in composition and energy content of liveweight loss in dairy cows with time after parturition. Livestock Prod Sci 52, 129-155.
92. Thatcher WW, Bilby TR, Bartolome JA, Silvestre F, Staples CR, Santos JEP, 2006: Strategies for improving fertility in the modern dairy cow. Theriogenology 65, 30-44.
93. Van Knegsel ATM, Van den Brand H, Dijkstra J, Van Straalen WM, Heetkamp MJW, Tamminga S, Kemp B, 2007a: Dietary energy source in dairy cows in early lactation: energy partitioning and milk composition. J Dairy Sci 90, 1467-1476.
94. Van Knegsel ATM, Van den Brand H, Dijkstra J, Van Straalen WM, Jorritsma R, Tamminga S, Kemp B, 2007b: Effect of glucogenic vs. lipogenic diets on energy balance, blood metabolites, and reproduction in primiparous and multiparous dairy cows in early lactation. J Dairy Sci 90, 3397-3409.
95. Vanholder T, Leroy JLMR, Dewulf J, Duchateau L, Coryn M, De Kruif A, 2005a: Hormonal and metabolic profiles of high-yielding dairy cows prior to ovarian cyst formation or first ovulation post partum. Reprod Domest Anim 40, 460-469.
96. Vanholder T, Leroy JLMR, Van Soom A, Opsomer G, Maes D, Coryn M, De Kruif A, 2005b: Effect of non-esterified fatty acids on bovine granulosa cell steroidogenesis and proliferation in vitro. Anim Reprod Sci 87, 33-44.
97. Vanholder T, Opsomer G, De Kruif A, 2006a: Aetiology and pathogenesis of cystic ovarian follicles in dairy cattle: a review. Reprod Nutr Dev 46, 105-119.
98. Vanholder T, Leroy JLMR, Van Soom A, Maes D, Coryn M, Fiers T, De Kruif A, Opsomer G, 2006b: Effect of non-esterified fatty acids on bovine theca cell steroidogenesis and proliferation in vitro. Anim Reprod Sci 92, 51-63.
99. Vernon RG, 2002: Nutrient partitioning, lipid metabolism and relevant imbalances. Proceedings of the 12th World Buiatrics Congress, Hannover, Germany, 18-23 August, 2002.
100. Villa-Godoy A, Hughes TL, Emery RS, Chapin LT, Fogwell RL, 1988: Association between energy balance and luteal function in lactating dairy cows. J Dairy Sci 71, 1063-1072.
101. De Vries MJ, Veerkamp RF, 2000: Energy balance of dairy cattle in relation to milk production variables and fertility. J Dairy Sci 83, 62-69.
102. Wade GN, Jones JE, 2004: Neuroendocrinology of nutritional infertility. Am J Physiol. Regul, Integrative Comp Physiol 287, 1277-1296.
103. Wathes DC, Fenwick M, Cheng Z, Bourne N, Llewellyn S, Morris DG, Kenny D, Murphy J, Fitzpatrick R, 2007: Influence of negative energy balance on cyclicity and fertility in the high producing dairy cow. Theriogenology 68, S232-S241.
104. Webb R, Garnsworthy PC, Gong JG, Robinson RS, Wathes DC, 1999: Consequences for reproductive function of metabolic adaptation to load. Anim Sci Occasion Publ 24, 99-112.
105. Wilson SJ, Marion RS, Spain JN, Spiers DE, Keisler DH, Lucy MC, 1998: Effect of controlled heat stress on ovarian function in dairy cattle: I. Lactating cows. J Dairy Sci 1, 2124-2131.
106. Wiltbank MC, Sartori R, Sangsritavong S, Lopez H, Haughian JM, Fricke PM, Gumen A, 2001: Novel effects of nutrition on reproduction in lactating dairy cows. J Dairy Sci Suppl 84, 32 (abstract).
107. Wiltbank M, Lopez H, Sartori R, Sangsritavong S, Gümen A, 2006: Changes in reproductive physiology of lactating dairy cows due to elevated steroid metabolism. Theriogenology 65, 17-29.
108. Wolfenson D, Lew BJ, Thatcher WW, Graber Y, Meidan R, 1997: Seasonal and acute heat stress effects on steroid production by dominant follicles in cow. Anim Reprod Sci 47, 9-19.
109. Wynne K, Stanley S, McGowan B, Bloom S, 2005: Appetite control. J Endocrinol 184, 291-318.
110. Yaakub H, O'Callaghan D, Boland MP, 1999: Effect of roughage type and concentrate supplementation on follicle numbers and in vitro fertilisation on follicle numbers and in vitro fertilisation and development of oocytes recovered from beef heifers. Anim Reprod Sci 44, 1-12.
111. Zhao F, Dixon WT, Kennelly JJ, 1996: Localization and gene expression of glucose transporters in bovine mammary gland. Comprehens Biochem Physiol 115, 127-134.
112. Zieba DA, Amstalden M, Williams GL, 2005: Regulatory roles of leptin in reproduction and metabolism: a comparative review. Domest Anim Endocrinol 29, 166-185.