Research Summary - 1

Effect of preweaning plane of nutrition on abomasal dynamics in Holstein calves.

Date/Time: 9/24/2020    13:45
Author: Ben  Kasl
Clinic: Texas Tech University
City, State, ZIP: Lubbock, TX  79415

B.A. Kasl, DVM 1 ; C.K. Hoff, MSc 1 ; T.H. Silva, DVM 1 ; I. Caetano, DVM 1 ; V.S. Machado, DVM, PhD 1 ; J.A. Carroll, PhD 2 ;
1Department of Veterinary Sciences, Texas Tech University, Lubbock, TX, 79409
2USDA-ARS Livestock Issues Research Unity, Lubbock, TX, 79401

Introduction:

Feeding dairy calves a higher plane of nutrition (PON) through either greater quantities of milk solids or fluid volume has become increasingly common on commercial operations. Administering more nutrient dense milk rations may compromise the functionality and environment of the abomasum potentially resulting in clinical abomasal pathologies. The objectives of this experiment were to determine the effects of PON on the abomasal environment in healthy Holstein calves.

Materials and Methods:

Fifteen bull calves (2 ± 1 d of age) with adequate passive transfer of immunity (serum total protein > 5.2 g/dL) were randomly assigned to 1 of 2 milk replacer (MR) diets. The low PON MR diet (LOW) consisted of 450 g/d of 22% CP – 20% fat MR (10.7% solids); calves fed the high PON MR diet (HI) were allocated 1100 g/d of 26% CP – 20% fat MR (15.5% solids). An abomasal cannula was surgically placed in each calf on d 5. From d 1 – d 8, all calves were fed LOW; assigned treatment diets started on d 9. On d 14, acetaminophen (50 mg/kg) was added into each MR aliquot to indirectly assess abomasal emptying rate (AER). Peripheral blood samples were collected at 0, 1, 2, 3, 4, 6, and 8 h following MR administration for plasma acetaminophen analysis. Postprandial abomasal fluid samples were collected at 0, 1, 2, 4, 6, and 8 h to measure gastric pH and ex-vivo pathogenic bacterial growth potential of Clostridium perfringens Type A (CPA) and Salmonella typhimurium (ST). Repeated measures data were analyzed using PROC MIXED in SAS.

Results:

Abomasal pH was greater in HI relative to LOW calves at 1 (6.03 vs. 5.37), 2 (5.76 vs. 5.06), 4 (4.52 vs. 3.17), and 6 h (3.41 vs. 1.67) postprandially (P≤0.001). The AER, defined as the time to maximal acetaminophen concentration, was significantly reduced in calves fed a HI (P=0.025). Ex-vivo CPA counts tended to be greater for HI calves (P=0.083); however, PON did not affect ST counts (P=0.406).

Significance:

Increased level of MR nutrition alters abomasal pH and emptying rate thereby affecting the growth of potentially pathogenic bacteria within luminal contents during the postprandial phase. Optimizing high plane of nutrition milk feeding protocols may alleviate their effects on the abomasal compartment while maximizing performance and growth benefits.