Effect of fish oil and monensin on milk composition in dairy cows

Abstract

Cant, J. P., Fredeen, A. H., MacIntyre, T. Gunn, J. and Crowe, N. 1997. Effect of fish oil and monensin on milk composition in dairy cows. Can. J. Anim. Sci. 77: 125-131. Four primparous Holstein cows were used in a 4 × 4 Latin square with 21-d periods to determine the effect of redfish oil and monensin sodium on milk composition. The four dietary treatments were a basal diet (control), the basal diet plus 14.5 mg monensin kg -1 dietary dry matter (M), 2% fish oil (FO), and a combination of fish oil and monensin (FO + M). Total DM intake, measured during the last week of each period was reduced on the two fish oil treatments but an interaction with monensin depressed intakes further. An additive inhibition of rumen fibre degradation is discussed. Differences in yields of milk and lactose were not shown to be significant among treatments. Milk fat content was reduced 29.8% by fish oil supplementation and protein content dropped 5.3%. Protein:fat ratios increased from 0.78 on the control ration to 1.08 on the fish oil treatments. Monensin, on the other hand, only caused a change in milk fat percentage, and that by a 7.5% decline. Fish oil increased the concentrations of 20-and 22-carbon fatty acids in milk, including the n-3 eicosapentaenoic and docosahexaenoic acids which were transferred at 9.3 and 16.2% efficiency from the diet, respectively. Monensin had no effect on milk fatty acid profile. The fish-oil-by-monensin interaction produced the poorest energy intakes and rates of energy deposition into milk. Milk fat consumption has been declining relative to that of protein. This is a major factor that has led to the adoption of milk component pricing systems and quotas based on production of milk fat. With the present quota system and value of milk components, profits for dairy farmers may be increased when the protein-to-fat ratio in milk is elevated above the current average of 0.85. Dietary modification shows the most promise as a management strategy to change milk composition in the short term.Added fat in a dairy ration has previously been shown to significantly reduce milk fat percentage (Nicholson and Sutton 1971;Brumby et al. 1972;Storry et al. 1974) and, although a decrease in milk protein percentage often accompanies the feeding of dietary lipid, protein yields are frequently improved (Sutton 1989;Coppock and Wilks 1991;DePeters and Cant 1992). Fish oil is a locally available fat supplement and is an excellent source of the n-3 fatty acids, eicosapentaenoic acid (EPA; C 20:5 (n-3) and docosahexaenoic acid (DHA; C 22:6 (n-3) . These fatty acids have been shown to impart health benefits to adult humans (Burr 1989) and are essential for normal development and function of the retina and nervous system (Sardesai 1992). There is considerable interest in providing natural sources of these fatty acids in the human diet. Enriching milk with n-3 fatty acids would

Apparent transfer efficiency of docosahexaenoic acid from diet to milk in dairy cows

“…The fish meal supplement linearly increased milk (22.9, 25.7, 26.5 kg d -1 , SE 1.12), protein, and lactose yields (P < 0.05; Wright et al 1998); however, there were linear declines (P < 0.01) in both milk fat yield (0.78, 0.71, and 0.62 kg d -1 , SE 0.03; Wright et al 1998) and content (3.35, 2.74, 2.38 g (100 g) -1 , SE 0.11) as supplementation increased from low to high, respectively. These data agree with literature that indicates the level of milk fat depression is dependent on the level of unprotected fish oil (present in fish meal) fed (Cant et al 1997).…”

Effects of Different Fat Sources on Fermentative Characteristics and Microbial Efficiency in the Rumen, and Nutrients Digestibility of Dairy Cows

“…However, the present results indicated that fish oil had no negative effect on DM intake. Unlike to the present study, this is because silage and concentrate were fed separately so the reduction in ad libitum silage intake by addition of fish oil to the concentrate suggests a more general effect on feed consumption in the work of Cant et al(1997). While all nutrients flow to the duodenum, and digestion in the rumen and total tract were not significantly different among the treatments.…”

“…Other researchers have also reported a decrease in DM intake of dietary source when cows are infused with unsaturated fat (Bremmer et al, 1998). In addition, Cant et al (1997) observed that a decreased 10% in DM intake was noted when the fish oil diets were fed because the diets had a fish odour which may have reduced cow's palatability. However, the present results indicated that fish oil had no negative effect on DM intake.…”

Effect of dietary enrichment with either n-3 or n-6 fatty acids on systemic metabolite and hormone concentration and ovarian function in heifers

“…This may have been a consequence of greater ruminal biohydrogenation and/or a poorer efficiency of absorption. While the majority of studies have shown a greater rate of transfer from diet to milk for DHA compared with EPA (Cant et al, 1997;Mattos et al, 2004), a recent study from our laboratory has shown EPA to be transferred more efficiently to a number of key reproductive tissues including uterine endometrium and follicular fluid .…”