cow to sub-acute rumen acidosis. Alternatively, more fre- quent offerings of feed may result in cows spreading out their feeding time more evenly throughout the day. Further, a steady input of nutrients into the rumen over the day should benefit rumen function, which in turn may reduce the risk of sub-acute rumen acidosis.
Mastitis It appears that cows supplemented with vitamin E at 740 mg/d during the dry period have a 37% lower incidence of mastitis after calving than control cows. The combination of vitamin E and selenium at 0.3 ppm in the total ration re- duced the number of quarters that had clinical signs of mastitis by 41%. These results provide evidence for an inter- action between vitamin E and selenium in controlling mas- titis. A later study reported a 42% decrease in the incidence of mastitis at calving in heifers that were supplemented with vitamin E and selenium for 60 days before calving. Supplementation of copper (as copper sulfate or copper proteinate) to heifers prepartum may also help reduce the incidence and severity of mastitis at calving. Heifers supple- mented with 20 ppm copper before calving have less infect- ed quarters after calving than heifers not supplemented with copper.
G.I. parasites Animals on low protein diets are more susceptible to
parasite infection because they produce less immuno- globulin IgA. Protein supplements should then be consid- ered, particularly for young susceptible animals in order to improve resistance to parasites. Animals infected with parasites use less calcium and phos- phorus and should therefore be provided with an adequate supply of calcium and phosphorus to compensate for the deficiency. Vitamin A is also important to improve the intestinal epithe- lial integrity and the function of the intestinal immune system, both of which are disrupted by parasitism.
External parasites External parasite infestation can adversely affect the protein status of the animal. Assuming an animal is infested with 200 ticks, it may lose 200 ml of blood or 40 g of protein (as- suming that blood is 20% protein) each day. With such a loss of protein, animals also produce more heat and the ME utili- zation will thus be lower. In this case, there will be reduced self-grooming with shedding of hair, and animals will beco- em more susceptible to further infestation. The increased re- quirements for a protein of 40 g could be met either by feed- ing an extra 150 g of cottonseed meal or by feeding an extra 250 g of digestible carbohydrate to allow the production of more microbial protein in the rumen.
References are available from the author upon request ▶ ALL ABOUT FEED | Volume 28, No. 7, 2020 29
Plants such as clover are known to accu- mulate nitrates to dangerous
levels.The provi- sion of addition- al roughage and concentrates re- duces the inci- dence of nitrate poisoning.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36
