Effects of meeting the requirements in energy and protein, and of systemic inflammation on the interval from parturition to conception in dairy cows

Abstract

Main aim of this retrospective study was to determine the role of the level of meeting the requirements in net energy of lactation (NE<sub>L</sub>) and utilizable crude protein at the duodenum (uCP) in weeks 3–17 postpartum on the interval from parturition until conception (IUC) in dairy cows. We compared intakes and balances of NE<sub>L</sub> and uCP, body weight change, metabolic status, reticuloruminal pH, and serum amyloid A (SAA) as a systemic inflammation marker in 30 dairy cows differing in the IUC length (i.e., short (S; n = 8), medium (M; n = 11), and long (L; n = 11) IUC for cows confirmed pregnant within week 10 or between weeks 11 and 17 postpartum, or thereafter, respectively). Data showed that the level of meeting the requirements in NE<sub>L</sub> and uCP in weeks 3–10 postpartum was instrumental in shortening the IUC in the cows pertaining to S IUC group (P ≤ 0.03). As an average, during this period the S cows met 104 and 110% of their requirements in NE<sub>L</sub> and uCP, respectively. In contrast, the M and L cows met 96 and 95% of NE<sub>L</sub> as well as 104 and 101% of uCP requirements, respectively. The M cows showed higher milk and blood urea nitrogen (P = 0.04), and also lower SAA concentration (P = 0.05) compared to L cows. In conclusion, exceeding the requirements in both NE<sub>L</sub> and uCP in weeks 3–10 postpartum significantly shortened the IUC to less than 10 weeks. The shorter IUC in M vs L cows went along with improved protein status and lesser systemic inflammation in week 6 postpartum in these cows.