The use of test day information to predict energy intake of dairy cows in early lactation

Genetic parameters for milk fatty acid composition of Holstein in Korea

Objective

Milk fatty acid (FA) is a main nutritional component that markedly effects human health. Intentional modification of the FA profile has the potential to improve milk quality. This study aimed at the factors affecting elevated FA levels and the estimation of the genetic parameters for milk FAs in the Korean Holstein population.

Methods

Total 885,249 repeated test-day milk records including, milk yield, saturated fatty acids (SFA), polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA), total unsaturated fatty acids (TUFA), fat and protein percentages were analyzed using CombiFoss FT+ system (Foss Analytical A/S, Denmark). Genetic parameters were estimated by the restricted maximum likelihood procedure based on the repeatability model using the Wombat program.

Results

The FA profile varies along with the lactation and the energy balance (EB). With the negative EB in early lactation, mobilization of body fat reserves elevates the desirable FA levels. As a result of that, milk quality is increased by means of nutritionally and usability aspects during the early lactation. Moreover, heritability estimates for SFA, MUFA, PUFA, TUFA were 0.33, 0.42, 0.37, 0.41 respectively. According to the parity wise heritability analysis, first parity cows had relatively lower heritability for SFAs (0.19) than later parities (0.28).

Conclusion

Genetic parameters indicated that FAs were under stronger genetic control. Therefore, we suggest implementing animal breeding programs towards improving the milk FA profile.

Heat stress abatement during the postpartum period: effects on whole lactation milk yield, indicators of metabolic status, inflammatory cytokines, and biomarkers of the oxidative stress

The objective of this study was to determine the effect of cooling upon calving in alleviating the adverse effects of heat stress in Holstein lactating cows. Production performance, indicators of metabolic status, immune response, and biomarkers of oxidative stress were measured. Based on mature equivalent milk production, parity, and calving date, 46 multiparous lactating cows were allotted to groups of equal sizes (n = 23); heat stressed (HS; BW = 658 ± 28 kg [mean ± SD]; BCS = 2.7 ± 0.18; parity = 3 ± 0.12) and cooled (CL; BW = 668 ± 23 kg; BCS = 2.8 ± 0.14; parity = 3 ± 0.25). Cows were housed in sand-bedded individual stalls equipped with misters and fans which were on from 1000 to 1800 hours for CL group. DMI and milk yield were measured from calving for 7 wk. Body condition score and BW were recorded weekly. Blood samples were collected weekly to measure the metabolic and antioxidant status, inflammatory cytokines, and immunoglobulins. Rectal temperature was measured daily at 1400 hour. Mean daily maximum temperature, minimum relative humidity, and maximum temperature-humidity index was 37.0 °C, 31.9%, and 83.4 for HS and 27.3 °C, 44.9%, and 75.7 for CL, respectively. Heat-stressed cows exhibited greater rectal temperature (39.8 vs. 39.1 °C) and lower feed intake (19.8 vs. 21.3 kg/d) relative to CL cows. Milk yield, including raw (31.2 vs. 38.6 kg/d) and fat- and protein-corrected (32.1 vs. 35.7 kg/d) milk, was lower in HS vs. CL cows, respectively. The percentages of milk protein (3.25 vs. 3.06), lactose (4.73 vs. 4.58), and solids-not-fat (8.63 vs. 8.38) but not milk fat (4.31 vs. 3.59) were higher in HS cows than in CL cows, respectively. Somatic cell score was greater in HS cows as compared with CL cows. Cooled cows lost less body condition as compared with HS cows. Blood plasma concentrations of glucose, non-esterified fatty acids, and β-hydroxybutyric acid were lower in HS cows. Blood plasma concentrations of malondialdehyde (2.13 vs. 1.84 nmol/mL), reactive oxygen species (579 vs. 561 U/mL), and total antioxidant capacity (4.49 vs. 4.06 U/mL) were greater in HS cows than in CL cows. Blood plasma concentrations of the inflammatory cytokines (tumor necrosis factor-α, interleukin-1α, and interleukin-2) and immunoglobulins (IgA, IgM, and IgG) were lower in HS cows than in CL cows. These findings demonstrated that cooling dairy cows during the early postpartum improved the production performance, indicators of metabolic status, immune response, and antioxidant capacity.

Genetic parameter estimation for milk β-hydroxybutyrate and acetone in early lactation and its association with fat to protein ratio and energy balance in Korean Holstein cattle

Objective

The objective of this study was to estimate the genetic parameters for milk β-hydroxybutyrate (BHBA), acetone (Ac), fat protein ratio (FPR), and energy balance (EB) using milk test day records and investigate the effect of early lactation FPR and EB on milk ketone body concentrations.

Methods

Total 262,940 test-day records collected from Korea Animal Improvement Association during the period of 2012 to 2016 were used in this study. BHBA and Ac concentrations in milk were measured by Fourier transform infrared spectroscopy (FTIR). FPR values were obtained using test day records of fat and protein percentage. EB was calculated using previously developed equation based on parity, lactation week, and milk composition data. Genetic parameters were estimated by restricted maximum likelihood procedure based on repeatability model using Wombat program.

Results

Elevated milk BHBA and Ac concentrations were observed during the early lactation under the negative energy balance. Milk FPR tends to decrease with the decreasing ketone body concentrations. Heritability estimates for milk BHBA, Ac, EB, and FPR ranged from 0.09 to 0.14, 0.23 to 0.31, 0.19 to 0.52, and 0.16 to 0.42 respectively at parity 1, 2, 3, and 4. The overall heritability for BHBA, Ac, EB and FPR were 0.29, 0.32, 0.58, and 0.38 respectively. A common pattern was observed in heritability of EB and FPR along with parities.

Conclusion

FPR and EB can be suggested as potential predictors for risk of hyperketonemia. The heritability estimates of milk BHBA, Ac, EB, and FPR indicate that the selective breeding may contribute to maintaining the milk ketone bodies at optimum level during early lactation.

Monensin causes dose dependent inhibition of Mycobacterium avium subspecies paratuberculosis in radiometric culture

Background

Mycobacterium avium subspecies paratuberculosis (MAP) causes a chronic wasting diarrheal disease in ruminants called Johne's disease, that is evocative of human inflammatory bowel disease (IBD). Agents used to treat IBD, called "anti-inflammatories", immuno-modulators" and "immuno-suppressants" inhibit MAP growth in culture. We concluded that, unknowingly, the medical profession has been treating MAP since sulfasalazine's introduction in 1942. Monensin, called a "Growth Enhancer" in cattle, ameliorates Johne's disease without a documented mechanism of action. We hypothesized that Monensin would inhibit MAP in culture.

Methods

Using the radiometric ¹⁴CO₂ Bactec^® system, that expresses mycobacterial growth in arbitrary growth index (GI) units, we studied the effect of Monensin on the growth kinetic of MAP isolated from humans with IBD ("Dominic", "Ben" & UCF-4) and cattle with Johne's disease (303 & ATCC 19698.) Results are expressed as percent inhibition of cumulative GI (%–ΔcGI).

Results

The positive control Clofazimine inhibits every strain tested. The negative controls Cycloheximide & Phthalimide, have no inhibition on any MAP strain. Monensin has dose dependent inhibition on every MAP strain tested. The most susceptible human isolate was UCF-4 (73% – ΔcGI at 1 μg/ml) and bovine isolate was 303 (73% – ΔcGI at 4 μg/ml.) Monensin additionally inhibits M. avium ATCC 25291 (87% – ΔcGI at 64 μg/ml) & BCG (92% – ΔcGI at 16 μg/ml).

Discussion

We show that in radiometric culture the "Growth Enhancer" Monensin causes dose dependent inhibition of mycobacteria including MAP. We posit that the "Growth Enhancer" effect of Monensin may, at least in part, be due to inhibition of MAP in clinical or sub-clinical Johne's disease.