Review/Oorsig Volume 22, Issue 03 - Page 19

Volume 22 • Issue 03 • 2018 Input-metabolism-output relationships for Calcium, Magnesium, Sodium and Potassium INPUT THROUGHPUT OUTPUT Mineral Dietary intake (g/day) Absorbed intake (g/day) Total reserves (g) Available reserves (g) Endogenous loss (g/day) Milk loss (g/day) Ca 100.0 34.0 6000 3.0 8.0 26.0 Na 19.5 19.5 700 35.0 6.5 13.0 Mg K 20.0 50.5 4.0 50.5 From: Metabolic and Nutritional Diseases of Cattle, J.M. Payne 175 0.75 820 185.0 1.5 22.5 2.5 28.0 The high risk period The definitions of terms are indicated in the following diagramme: Dry-off Dry period (60 days) Start of new lactation Steam-up 21 d Negative Energy Balance 75-90 d Transition period 42 d BAROMETER End previous lactation → 305 days Calving Over the last approximately 50 years, genetic selection has led to markedly increased milk production ability of dairy cows. At the same time, despite advancements in technology and knowledge to prevent production diseases, the incidence of these diseases has stayed more or less unchanged. The same applies for reproduction parameters, except in the case of reproduction the situation has deteriorated and not just stayed the same. There is now some physiological evidence that the mismatch between milk production ability (genetic) and management (including nutrition) leads to deterioration in oocyte quality and embryo survival. In other words, reproduction (or production diseases for that matter) acts as a barometer for the mismatch between advances in genetics for production, and improvement in management practices to sustain such high production in the cows. The following diagramme illustrates this principle: Production vs Health and Reproduction M ANAGE- M ENT Leroy JLMR 2009 Nutrient prioritisation in dairy cows early post partum: Mismatch between metabolism and fertility? Annual conference of the Livestock Health and Production Leroy JLMR 2009 Nutrient prioritisation in dairy cows early post partum: Mismatch between Group of SAVA, 21 conference - 23 July of 2009, Mossel South Group of metabolism and the fertility? Annual the Livestock Health Bay, and Production the Africa SAVA, 21 – 23 July 2009, Mossel Bay, South Africa It is important to consider production diseases on a herd basis, in order to predict occurrence and set up preventative measures. This can be a fW'6Vvr'WB6WG&VVǐ&Wv&FrF6FFR&7F6rfWFW&&