Metabolic and productive responses of dairy cows to increased ion supplementation at early lactation in warm weather.
We found previously that the current recommendations for Na+, K+, and Cl- contents in the diet do not meet the needs of lactating cows. The response of cows receiving a ration with increased amounts of Na+, K+, and Cl- (E cows) were compared with those of cows consuming the same ration with a fixed concentration of these ions (C cows) between weeks 2 and 8 post partum (PP). Milk, protein, fat and lactose yields, and dry matter intake between weeks 2 and 4 PP were higher in E than in C cows. These differences did not occur between weeks 4 and 8 PP, mainly because of a higher incidence of PP complications in E cows. A greater increase in plasma insulin-like growth factor-1 concentration in E than in C animals during weeks 2 and 3 PP was consistent with the milk responses. A reduction in aldosterone concentration in E cows in weeks 2 and 3 PP was a consequence of their Na+ requirements being satisfied as a result of their enhanced Na+ intake. A subsequent elevation in aldosterone concentration in E animals was probably related to a moderate excess in K+ intake. This increase in aldosterone explains the urinary potassium loss that was detected at week 6 PP. The absence of differences between E and C cows in plasma renin activity was consistent with an absence of differences in urine volume and with the apparent utilization of the enhanced ion intake for body functions.
Silanikove
N
N
Institute of Animal Science, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel.
Maltz
E
E
Shinder
D
D
Bogin
E
E
Bastholm
T
T
Christensen
N J
NJ
Norggarrd
P
P
D000450:Aldosterone / Q000097:blood; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D002712:Chlorides / Q000008:administration & dosage*; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006358:Hot Temperature; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007668:Kidney / Q000502:physiology; D007774:Lactation; D007785:Lactose / Q000032:analysis; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D008903:Minerals / Q000032:analysis; D009751:Nutritional Requirements; D011188:Potassium / Q000008:administration & dosage* / Q000652:urine; D012083:Renin / Q000097:blood; D012982:Sodium, Dietary / Q000008:administration & dosage*
D002712:Chlorides; D008894:Milk Proteins; D008903:Minerals; D012982:Sodium, Dietary; D000450:Aldosterone; D007334:Insulin-Like Growth Factor I; D012083:Renin; D007785:Lactose; D011188:Potassium