Ruminantlarda Beslenmenin Süt Verimi ve Kalitesi Üzerine Etkisi

Öz

Süt sığırcılığında başarı, maliyet hesaplamaları göz önünde bulundurularak en iyi rasyonla en yüksek süt verimini elde edebilmektir. Süt verimi temelde, beslenme dışı ve beslenmeye bağlı faktörler olmak üzere iki başlıkta ele alınabilir. Bu amaçla; beslenme dışı (genotip, laktasyon, barındırma, sağım uygulamaları, yaş ve cüsse, kuruda kalma süresi, kızgınlık ve gebelik, ikizlik, çevre, buzağılama mevsimi, gün ışığı, egzersiz, ilaçlama, hormonlar) ve beslenmeye bağlı (besleme aralığı, karbonhidratlar, yağlar, proteinler, somatik hücre sayısı, vitaminler, mineraller, su ve yem katkı maddeleri) faktörler irdelenmiştir. Beslenmeye bağlı protein, laktoz, su, mineraller ve yağlar gibi birçok faktör süt kompozisyonunu etkiler. Süt bileşenlerinden en çok yağ ve protein rasyon değişikliklerinden etkilenmektedir. Diğer süt bileşenleri, laktoz ve mineraller rasyon değişikliklerinden çok fazla etkilenmezler. Yetiştiricilikte hastalıkların %80’inin beslenmeye bağlı olduğu ve en iyi verimi elde etmede beslenmenin ne kadar önemli olduğu düşünüldüğünde beslenmeye gereken özenin gösterilmesi büyük önem taşımaktadır. Bu çalışmada; ruminantlarda beslenmeye bağlı faktörlerin süt kompozisyonu ve verimi üzerindeki etkileri derlenmiştir.

Anahtar Kelimeler

• Süt sığırı
• Besleme
• Süt verimi

The Effect of Nutrition on Milk Yield and Quality in Ruminants

Abstract

Success in dairy cattle breeding is to obtain the highest milk yield with the best ration, taking into account cost calculations. Milk yield can be basically discussed under two headings as non-nutritive and nutrition-related factors. To this end; non-nutritional (genotype, lactation, housing, milking practices, age and size, drying time, heat and pregnancy, twins, environment, calving season, daylight, exercise, spraying, hormones, feeding interval) and nutritional (carbohydrates, fats, proteins, somatic cell number, vitamins, minerals, water and feed additives) factors were examined. Many factors such as dietary protein, lactose, water, minerals and fats affect milk composition. Milk components are mostly affected by fat and protein ration changes. Other milk components, lactose and minerals are not much affected by ration changes. Considering that 80% of diseases in aquaculture depend on nutrition and how important nutrition is in obtaining the best efficiency, it is of great importance to pay attention to nutrition. In this study; The effects of nutritional factors on milk composition and yield in ruminants were compiled.

Keywords

• Dairy cattle
• Nutrition
• Milk yield

Kaynakça

1. Abdouli, H., Rekik, B. ve Haddad-Boubaker, A. (2008). Non-nutritional factors associated with milk urea concentrations under Mediterranean conditions. World Journal of Agriculture Science, 4(2), 183-188.
2. Amaral-Phillips, D. M. (2009). Milk urea nitrogen-a nutritional evaluation tool. Extension Dairy Nutritionist. University of Kentucky.
3. Anonim. (2005). Sütteki somatik hücre sayısı. Erişim adresi (Mart, 2014): http:/vetstaff.s5.com/shs.htm
4. Anonim. (2014). Dünya ve Türkiye’de Süt Sektör İstatistikleri 2013. Ulusal Süt Konseyi Yayını.
5. Anonim. (2019). Beslenmenin Süt Bileşenleri Üzerine Etkisi. Erişim adresi: https://www.biomin.net/species/ruminants.
6. Armentano, L. E., Bertics, S. J. ve Ducharme, G. A. (1997). Response of lactating cows to methionine or methionine plus lysine added to high protein diets based on alfalfa and heated soybeans. Journal of Dairy Science, 80(6), 1194–1199. https://doi.org/10.3168/jds.s0022-0302(97)76047-8
7. Atasever, S. ve Erdem, H. (2009). Estimation of milk yield and financial losses related to somatic cell count in Holstein cows raised in Turkey. Journal of Animal and Veterinary Advances, 8(8), 1491-1494.
8. Ayaşan, T. (2009). Süt ineklerinin beslenmesinde süt üre nitrojenin önemi. Gaziosmanpaşa Üniversitesi Ziraat Fakültesi Dergisi, 26(2), 27-33.

9. Ayaşan, T. ve Karakozak, E. (2010). Hayvan beslemede β-karoten kullanılması ve etkileri. Kafkas Üniversitesi Veteriner Fakültesi Dergisi, 16(4), 697-705. https://doi.org/10.9775/kvfd.2010.2008
10. Ayaşan, T. ve Karakozak, E. (2011). Korunmuş Yağların Hayvan Beslemede Kullanımı. Atatürk Üniversitesi Veteriner Bilimleri Dergisi, 6(1), 85-94.
11. Ayoade, J. A., Buttery, P. J. ve Lewis, D. (1982). Studies on methionine derivatives as possible sources of protected methionine in ruminant rations. Journal of the Science of Food and Agriculture, 33(10), 949–956. https://doi.org/10.1002/jsfa.2740331003
12. Baker, L. D., Ferguson, J. D. ve Chalupa, W. (1995). Responses in urea and true protein of milk to different protein feeding schemes for dairy cows. Journal of Dairy Science, 78(11), 2424–2434. https://doi.org/10.3168/jds.s0022-0302(95)76871-0
13. Beauchemin, K. A., Colombatto, D., Morgavi, D. P. ve Yang, W. Z. (2003). Use of exogenous fibrolytic enzymes to improve feed utilization by ruminants. Journal of Animal Science, 81(14_suppl_2), E37-E47.
14. Beede, D. K. (2017). Large Dairy Herd Management (Third Edition). Drinking water for dairy cattle. Champaign, IL: American Dairy Science Association.
15. Benchaar, C., Petit, H. V., Berthiaume, R., Whyte, T. D. ve Chouinard, P. Y. (2006). Effects of Addition of Essential Oils and Monensin Premix on Digestion, Ruminal Fermentation, Milk Production, and Milk Composition in Dairy Cows. Journal of Dairy Science, 89(11), 4352–4364. https://doi.org/10.3168/jds.s0022-0302(06)72482-1
16. Bequette, B. J., Backwell, F. R. C. ve Crompton, L. A. (1998). Current concepts of amino acid and protein metabolism in the mammary gland of the lactating ruminant. Journal of Dairy Science, 81(9), 2540–2559. https://doi.org/10.3168/jds.s0022-0302(98)70147-x
17. Bilal, T., Keser, O. ve Abaş, İ. (2008). Esans yağların hayvan beslemede kullanılması. Erciyes Üniversitesi Veteriner Fakültesi Dergisi, 5(1), 41-50.
18. Broderick, G. A., Stevenson, M. J., Patton, R. A., Lobos, N. E. ve Olmos Colmenero, J. J. (2008). Effect of supplementing rumen-protected methionine on production and nitrogen excretion in lactating dairy cows. Journal of Dairy Science, 91(3), 1092–1102. https://doi.org/10.3168/jds.2007-0769
19. Craninx, M., Fievez, V., Vlaeminck, B. ve De Baets, B. (2008). Artificial neural network models of the rumen fermentation pattern in dairy cattle. Computers and Electronics in Agriculture, 60(2), 226–238. https://doi.org/10.1016/j.compag.2007.08.005
20. Çetin, H. ve Uçar, E. H. (2018). Doğum Sonrası Problemler ve Mastitis. Lalahan Hayvancılık Araştırma Enstitüsü Dergisi, 58(3, Özel sayı), 15-22.
21. Dann, H. M., Drackley, J. K., McCoy, G. C., Hutjens, M. F. ve Garrett, J. E. (2000). Effects of Yeast Culture (Saccharomyces cerevisiae) on Prepartum Intake and Postpartum Intake and Milk Production of Jersey Cows. Journal of Dairy Science, 83(1), 123–127. https://doi.org/10.3168/jds.s0022-0302(00)74863-6
22. Davis, S. R. (2017). Triennial Lactation Symposıum/Bolfa: Mammary growth during pregnancy and lactation and its relationship with milk yield. Journal of Animal Science, 95(12), 5675–5688. https://doi.org/10.2527/jas2017.1733
23. De Ondarza, M. B., Wilson, J. W. ve Engstrom, M. (2009). Case Study: Effect of supplemental β-carotene on yield of milk and milk components and on reproduction of dairy cows. The Professional Animal Scientist, 25(4), 510–516. https://doi.org/10.15232/s1080-7446(15)30742-7
24. Deniz, S. ve Tuncer, Ş. D. (1995). Bitkisel protein kaynaklarının formaldehit ile muamele edilmesinin rumen kuru madde ve ham protein ile effektif protein yıkılımı üzerine etkisi. Turkish Journal of Veterinary and Animal Sciences, 19, 1-8.
25. El-Nenaey, M., Soheir, H., Fawzy, A. ve Khattab, R. M. (1996). Effect of vitamine E and selenium supplementation on productive and reproductive performance of Egyptian Buffaloes. International Symposium on Buffalo Resources ve Production systems. 14-17 Oct., 1996, Cairo, Egypt, 62-69.
26. Ensminger, M. E. ve Howard, D. T. (1980). Dairy Cattle Science. The Interstate Printers and Publisher. Inc., Danville, IL.
27. Filya, İ. ve Canpolat, Ö. (2010). Süt ineklerinin beslenmesinde temel prensipler. Erişim adresi (27 Aralık 2010): www.selimarslan.com/downloadhandler.ashx
28. Firkins, J. L. ve Eastridge, M. L. (1994). Assessment of the Effects of Iodine Value on Fatty Acid Digestibility, Feed Intake and Milk Production. Journal of Dairy Science, 77(8), 2357–2366. https://doi.org/10.3168/jds.s0022-0302(94)77178-2.
29. Gabriella, A. V. ve Virginia, A. I. (2007). Managing nutrition for optimal milk components. Western Dairy Management Conference, March 7-9 Reno, NV.
30. Gencoglu, H., Shaver, R. D., Steinberg, W., Ensink, J., Ferraretto, L. F., Bertics, S. J., Lopes, J. C. ve Akins, M. S. (2010). Effect of feeding a reduced-starch diet with or without amylase addition on lactation performance in dairy cows. Journal of Dairy Science, 93(2), 723–732. https://doi.org/10.3168/jds.2009-2673
31. Goetsch, A. L., Zeng, S. S. ve Gipson, T. A. (2011). Factors affecting goat milk production and quality. Small Ruminant Research, 101(1-3), 55-63. https://doi.org/10.1016/j.smallrumres.2011.09.025.
32. Gök, K., Ayaşan, T., Tekgül, A., Hızlı, H., Karakozak, E., Kara, U., Çoban, S., Mutlu, H. ve Seğmenoğlu, M. S. (2012). Somatik hücre sayısının verici ineklerde embriyo kalitesine etkisi. Süleyman Demirel Üniversitesi Ziraat Fakültesi Dergisi, 7(2), 49-55.
33. Görgülü, M. (2009). Büyük ve Küçükbaş Hayvan Besleme. Çukurova Üniversitesi Ziraat Fakültesi Zootekni Bölümü Ders kitabı.
34. Grainger, C. ve Goddard, M. E. (2007, September). A review of the effects of dairy breed on feed conversion efficiency. In 3rd Dairy Sci. Symp. Meeting the Challenges of Pasture-Based Dairying, University of Melbourne, Victoria, Australia. CSIRO, Victoria, Australia (pp. 84-92).
35. Gülgün, E. (2020). Süt ineklerinde rasyona ilave edilen korunmuş metiyonin ve lizinin süt verimi ve süt kompozisyonu üzerine etkileri (Yüksek lisans tezi). Bursa Uludağ Üniversitesi, Fen Bilimleri Enstitüsü, Bursa.
36. Harmeyer, J. (2001). L-Carnitin. Grosstierpraksis, 2, 28-41.
37. Harris, B. (1992). Feeding to Combat Heat Stress. Feed International, 6, 30-33.
38. Hayes, W. B. (1984). Infertility and sterility in dairy cattle. British Colombia Ministry of Agriculture and Food. 17720-57 Avenue, Surrey, B. C. V354P9.
39. Hilali, M., El-Mayda, E. ve Rischkowsky, B. (2011). Characteristics and utilization of sheep and goat milk in the Middle East. Small Ruminant Research, 101(1-3), 92–101. https://doi.org/10.1016/j.smallrumres.2011.09.029
40. Hojman, D., Kroll, O., Adin, G., Gips, M., Hanochi, B. ve Ezra, E. (2004). Relationships between milk urea and production, nutrition and fertility traits in Israeli dairy herds. Journal of Dairy Science, 87(4), 1001–1011. https://doi.org/10.3168/jds.s0022-0302(04)73245-2
41. Hojman, D., Gips, M. ve Ezra, E. (2005). Association between live body weight and milk urea concentration in Holstein cows. Journal of Dairy Science, 88(2), 580–584. https://doi.org/10.3168/jds.s0022-0302(05)72721-1
42. Hosoda, K., Matsuyama, H., Park, W.-Y., Nishida, T. ve Ishida, M. (2006). Supplementary effect of peppermint (Mentha x piperita) on dry matter intake, digestibility, ruminal fermentation and milk production in early lactating dairy cows. Animal Science Journal, 77(5), 503–509. https://doi.org/10.1111/j.1740-0929.2006.00378.x
43. Islam, M. R., Uddin, M. N., Akanda, M. R., Khan, M. M. H., Baset, M. A. ve Belal, S. A. (2015). Effect of Milk Urea Nitrogen of Dairy Cows in Relation to Breed. Iranian Journal of Applied Animal Science, 5(2), 279-283.
44. Jenkins, T. C. (1998). Fatty Acid Composition of milk from Holstein cows fed oleamide or canola oil. Journal of Dairy Science, 81(3), 794–800. https://doi.org/10.3168/jds.s0022-0302(98)75636-x
45. Kamalak, A., Canbolat, Ö., Gürbüz, Y. ve Özay, O. (2004). Protect protein and aminoacids in ruminant nutrition. KSÜ Fen ve Mühendislik Dergisi, 8(2), 84-88.
46. Karademir, G. ve Karademir, B. (2003). Yem katkı maddesi olarak kullanılan biyoteknolojik ürünler. Lalahan Hayvancılık Araştırma Enstitüsü Dergisi, 43(1), 61-74.
47. Karakozak, E. ve Ayaşan, T. (2010). Ruminant beslemede korunmuş metionin kullanımı. Süleyman Demirel Üniversitesi Ziraat Fakültesi Dergisi, 5(1), 58-66.
48. Kholif, A. M. ve Ebeid, H. M. (2009). Effect of calcium soap supplementation without or with rumen-protected methionine and lysine on lactating buffaloes, ration on milk production and composition. Pakistan Journal Zoology, 9(supply), 697-700.
49. King, K. J., Bergen, W. G., Sniffen, C. J., Grant, A. L., Grieve, D. B., King, V. L. ve Ames, N. K. (1991). An Assessment of Absorbable Lysine Requirements in Lactating Cows. Journal of Dairy Science, 74(8), 2530–2539. https://doi.org/10.3168/jds.s0022-0302(91)78430-0
50. Kondyli, E., Svarnas, C., Samelis, J. ve Katsiari, M. C. (2012). Chemical composition and microbiological quality of ewe and goat milk of native Greek breeds. Small Ruminant Research, 103(2-3), 194–199. https://doi.org/10.1016/j.smallrumres.2011.09.043
51. Kopec, B. ve Fritz, I. B. (1973). Comparasion of properties of carnitine palmitoyltransferase I with those of carnitine palmitoyltransferase II and preparations of antibodies to carnitine palmitoyltransferases. Journal of Biological Chememistry, 248(11), 4069-4074. https://doi.org/10.1016/S0021-9258(19)43840-4
52. Lean, I. J., Annison, F., Bramley, E., Browning, G., Cusack, P., Farquharson, B., Little, S. ve Nandapi, D. (2007). Ruminal acidosis understandings, prevention and treatment. A review for veterinarians and nutritional professionals by the reference advisory group on fermentative acidosis of ruminants (RAGFAR). 1th ed., Australian Veterinary Association Publ., Australian.
53. Li, R. W., Wu, S., Baldwin, R. L., Li, W. ve Li, C. (2012). Perturbation dynamics of the rumen microbiota in response to exogenous butyrate. PLoS ONE, 7(1), e29392. https://doi.org/10.1371/journal.pone.0029392
54. Lucy, M. (2008). Functional differences in the growth hormone and insulin-like growth factor axis in cattle and pigs: Implications for post-partum nutrition and reproduction. Reproduction in Domestic Animals, 43, 31–39. https://doi.org/10.1111/j.1439-0531.2008.01140.x
55. McAllister, T. A., Hristov, A. N., Beauchemin, K. A., Rode, L. M. ve Cheng, K. J. (2001). Enzymes in ruminant diets. Enzymes in farm animal nutrition, 273-298. UK: Bowman CABI Publishing.
56. Mosley, S. A., Mosley, E. E., Hatch, B., Szasz, J. I., Corato, A., Zacharias, N., Howes, D. ve McGuire, M. A. (2007). Effect of Varying Levels of Fatty Acids from Palm Oil on Feed Intake and Milk Production in Holstein Cows. Journal of Dairy Science, 90(2), 987–993. https://doi.org/10.3168/jds.s0022-0302(07)71583-7
57. Moallem, U., Katz, M., Lehrer, H., Livshitz, L. ve Yakoby, S. (2007). Role of peripartum dietary propylene glycol or protected fats on metabolism and early postpartum ovarian follicles. Journal of Dairy Science, 90(3), 1243–1254. https://doi.org/10.3168/jds.s0022-0302(07)71613-2
58. NRC. (2001a). Nutrient requirements of dairy cattle. National Research Council, Washington, DC: National Academy Press.
59. NRC. (2001b). Nutrient requirements of sheep (Seventh revised edition). Washington, DC: National Academy Press.
60. NRC. (2016). Nutrient requirements of beef cattle, 8th Rev. Ed. Washington, DC: National Academy Press.
61. Önen, M. O. (1999). Süt ve süt ürünleri sektörü araştırması. Türkiye Kalkınma Bankası A. Ş. Sektörel Araştırmalar. SA/99-4-10. Sn:1.
62. Özek, K. (2015). Süt sığırlarında süt kompozisyonunu etkileyen faktörler ve besleme - süt kompozisyonu ilişkisi. Bahri Dağdaş Hayvancılık Araştırma Dergisi, 4(2), 37-45.
63. Park, Y. W., Juárez, M., Ramos, M. ve Haenlein, G. F. W. (2007). Physico-chemical characteristics of goat and sheep milk. Small Ruminant Research, 68(1-2), 88–113. https://doi.org/10.1016/j.smallrumres.2006.09.013
64. Patterson, J. A. ve Kung, L. (1988). Metabolism of DL-Methionine and methionine analogs by rumen microorganisms. Journal of Dairy Science, 71(12), 3292–3301. https://doi.org/10.3168/jds.s0022-0302(88)79934-8
65. Pereira, M. N., Garrett, E. F., Oetzel, G. R. ve Armentanto, L. E. (1999). Partial replacement of forage with Nonforage fiber sources in lactating cow diets. I. Performance and health. Journal of Dairy Science, 82(12), 2716–2730. https://doi.org/10.3168/jds.s0022-0302(99)75528-1
66. Pulido, E., Giráldez, F. J., Bodas, R., Andrés, S. ve Prieto, N. (2012). Effect of reduction of milking frequency and supplementation of vitamin E and selenium above requirements on milk yield and composition in Assaf ewes. Journal of Dairy Science, 95(7), 3527–3535. https://doi.org/10.3168/jds.2011-5048
67. Rodriguez, L. A., Stallings, C. C., Herbein, J. H. ve Mcgilliard, M. L. (1997). Diurnal variation in milk and plasma urea nitrogen in Holstein and Jersey cows in response to degradable dietary protein and added fat. Journal of Dairy Science, 80(12), 3368–3376. https://doi.org/10.3168/jds.s0022-0302(97)76312-4
68. Roy, B., Mehla, R. K. ve Sirohi, S. K. (2003). Influence of milk yield, parity, stage of lactation and body weight on urea and protein concentration in milk of Murrah buffaloes. Asian-Australasian Journal of Animal Sciences, 16(9), 1285-1290. https://doi.org/10.5713/ajas.2003.1285
69. Santos, M. B., Robinson, P. H., Williams, P. ve Losa, R. (2010). Effects of addition of an essential oil complex to the diet of lactating dairy cows on whole tract digestion of nutrients and productive performance. Animal Feed Science and Technology, 157(1-2), 64–71. https://doi.org/10.1016/j.anifeedsci.2010.02.001
70. Schroeder, J. W. (2012). Dairy cow nutrition affects milk composition. North Dakota State University Extension Service AS1118.
71. Sevgican, F. (1996). Ruminantların Beslenmesi. I. Baskı. Ege Üniversitesi Ziraat Fakültesi, Yayın No: 524, İzmir. 70-168.
72. Sniffen, C. J. ve Herdt, T. H. (1991). Preface. The Veterinary Clinics of North America: Food Animal Practice, 7(2), xi. https://doi.org/10.1016/S0749-0720(15)30782-9
73. St-Pierre, N. R. ve Sylvester, J. T. (2005). Effects of 2-hydroxy-4-(methylthio) butanoic acid (HMB) and its isopropyl ester on milk production and composition by holstein cows. Journal of Dairy Science, 88(7), 2487–2497. https://doi.org/10.3168/jds.s0022-0302(05)72926-x
74. Suttle, N. F. (2010). The mineral nutrition of livestock, 4th ed. (600 p.). Wallingford, Oxfordshire: CABI Publishing.
75. Suzuki, M. ve Van Vleck, L. D. (1994). Heritability and repeatability for milk production traits of Japanese Holsteins from an animal model. Journal of Dairy Science, 77(2), 583-588. https://doi.org/10.3168/jds.S0022-0302(94)76987-3
76. Şahan, Z. (2012). Bazı bitki uçucu yağlarının enerji, protein ve lif kaynağı yemlerın in vitro gerçek sindirilebilirliğine ve yüksek verimli süt sığırlarında süt verimi ve süt kompozisyonlarına etkileri (Doktora tezi). Çukurova Üniversitesi, Fen Bilimleri Enstitüsü, Adana.
77. Şekerden, Ö. (2000). Büyükbaş hayvan yetiştirme (Manda yetiştiriciliği). Çukurova Üniversitesi Ziraat Fakültesi Ders Kitabı.
78. Tekeli, T. (2005). AB sürecinde kaliteli süt üretimi ve somatik hücre sayısı (s. 19-35). Konya: Güzeliş Ofset Matbaa.
79. Van Knegsel, A. T. M., Van den Brand, H., Dijkstra, J., Van Straalen, W. M., Heetkamp, M. J. W., Tamminga, S. ve Kemp, B. (2007). Dietary energy source in dairy cows in early lactation: Energy partitioning and milk composition. Journal of Dairy Science, 90(3), 1467–1476. https://doi.org/10.3168/jds.s0022-0302(07)71632-6
80. Vicini, J. L., Bateman, H. G., Bhat, M. K., Clark, J. H., Erdman, R. A., Phipps, R. H., Van Amburgh, M. E., Hartnell, G. F., Hintz, R. L. ve Hard, D. L. (2003). Effect of Feeding Supplemental Fibrolytic Enzymes or Soluble Sugars with Malic Acid on Milk Production. Journal of Dairy Science, 86(2), 576–585. https://doi.org/10.3168/jds.s0022-0302(03)73636-4
81. Walstra, P., Wouters, J. T. M. ve Geurts, T. J. (2006). Dairy Science ve Technology (p. 763). Taylor & Francis Group. Boca Raton, FL: CRC Press.
82. West, W. J. (1995). Managing and feeding lactating dairy cows in hot weather. The University of Georgia College of Agricultural and Environmental Sciences and the U.S Department of Agriculture.
83. Williams, G. L. ve Stanko, R. L. (1999). Dietary fats as reproductive nutraceuticals in beef cattle. Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville 78102-9410. Proc. Am. Soc. Anim. Sci.
84. Yalçın, S., Yalçın, S., Can, P., Gürdal, A. O., Bağcı, C. ve Eltan, Ö. (2011). The Nutritive Value of Live Yeast Culture (Saccharomyces cerevisiae) and Its Effect on Milk Yield, Milk Composition and Some Blood Parameters of Dairy Cows. Asian-Australasian Journal of Animal Sciences, 24(10), 1377–1385. https://doi.org/10.5713/ajas.2011.11060
85. Zheng, W., Schingoethe, D. J., Stegeman, G. A., Hippen, A. R. ve Treacher, R. J. (2000). Determination of When During the Lactation Cycle to Start Feeding a Cellulase and Xylanase Enzyme Mixture to Dairy Cows. Journal of Dairy Science, 83(10), 2319–2325. https://doi.org/10.3168/jds.s0022-0302(00)75119-8
86. Ziegler, K. (2000). Nutrition and Management: Types and Sources of Protein. Erişim adresi (26 Şubat 2010): http://www.agric.gov.ab.ca/Sdepartment/deptdocs.nsf/all/beef11678