Colostrum in NY Holsteins: Metabolic indicators and affected by prepartum nutrition
Part two: A look at role of nutrition and colostrum yield
By Al Kertz, PhD, PAS, DIPL ACAN
In a previous webinar/article we featured a study of New York Holstein herds and colostrum epidemiology (Kertz, 2023; Westhoff et al., 2023a).
Herds were selected based on participation in previous statewide research projects, and by contacting veterinarians and nutritionists. Inclusion criteria were:
Ability to collect and record individual colostrum weight or volume and a composite sample Brix % reading
Minimum herd size of 500 lactating Holstein cows
Use of dairy management software DairyComp 305
Heifer calves housed on site for at least the first week of life.
A total of 51 farms were contacted from October 2019 to January 2020. After herd owners responded whether to participate or qualify, 19 New York state Holstein herds were enrolled in the study. “The survey was comprised of both open and closed questions related to dry off procedures, pen movement, dry period nutrition strategies, transition cow housing, calving environment, colostrum harvest protocols, colostrum management and feeding, and preweaning calf management.”
Colostrum yield was either collected as a volume or as a weight (n = 15). A Brix refractometer was provided to each farm and farm personnel were trained on the correct use of the instrument for composite same Brix % reading. Colostrum was recorded for cow ID, date and time of colostrum harvest, bucket color, colostrum yield, Brix %, notes, and the initials of the individual responsible for colostrum collection. Two environmental data loggers were utilized measuring light intensity and ambient temperature/relative humidity in 15- and 30-minute intervals during the entire study period. Temperature-humidity index was calculated from measurements. An extensive description in the paper is provided for how data were analyzed.
Of the 19 herds in the study, 21,374 individual animal colostrum records were collected from 18 herds. Herd sizes ranged from 620 to 4,600 with most in the 1,000 to 2,000 cow herd size. Median colostrum yield was 4.0 liters with 24.6% Brix for first-calf heifers, and 4.6 liters (highest in 2nd lactation) with 25.7% Brix for older cows. Colostrum was fed to calves from harvest in 95% of herds within 2 hours.
Diets for heifers fed beginning 60 days prepartum were sampled at each visit as were diets fed to dry cows (Westhoff et al., 2023b). Particle size was determined using the Penn State Particle Separator and nutrients analyzed by a commercial laboratory.
Blood was collected from the coccygeal vein or artery at 3-14 days before expected parturition. A sample of 8 first-calf and 16 older cows were sampled. Body condition was scored at the same time and with the same animals as blood was sampled. Scoring (BCS) was on a 5-poing scale and in 0.25 increments. 1
Herd prevalence of hyperketonemia was based on the same animals and sampling as for BCS and blood with BHB (beta hydroxy butyric acid) of ≥ 1.2 mMole/L.
Results were:
Overall, 13 herds were visited 3 times, and 6 farms visited 4 times during the study as COVID-19 caused modification of original protocol.
Two herds fed separate closeup diets to heifers and cows.
Starch was mainly in the low 20% range, amylase NDF had a wider range reflected by the mean and median difference and SD, CP was around 14.5% and with a low SD of 1.6, DCAD was negative with a similar mean and median but a high SD of 7.3 (this might indicate some farms did not formulate for DCAD at all), peNDF had a wide range, ≥ 19 mm had similar mean and median but with a wide range and high SD, % hyperketonemia had a wide range and SD as great as mean and median (Table 1).
The final model found colostrum yield was associated (P<0.01) with diet content of
Starch
CP
DCAD
Proportion of the diet with particle length ≥ 19mm and prevalence of hyperketonemia
A moderate herd prevalence of hyperketonemia (10.1-15.0%) was associated with the greatest colostrum yield.
Diet content x parity group (1 vs. ≥2) interactions were identified for starch, CP, DCAD, and proportion of the diet with particle length ≥19 mm such that greatest colostrum yield from older cows was associated with moderate CP (13.6-15.5% of DM) and a less severe negative DCAD (>-8 mEq/100 g) whereas greatest colostrum yield from first-calf heifers was associated with low CP (≤13.5%). and colostrum yield from first-calf heifers was not associated with DCAD (P = 0.06).
In addition, lowest colostrum yield from older cows was associated with low starch (≤18.5% of DM).but lowest colostrum yield from first-calf heifers was associated with high starch (>22.5% of DM).
Colostrum Brix % was greatest with low aNDF (≤ 39.0% of DM) and a high proportion of the diet with particle length ≥ 19 mm (>19.1%). Diet content x parity group interactions were identified for starch (P<0.01) and DCAD (P <0.01) such that greatest colostrum Brix % from first-calf heifers was associated with low starch (≤ 18.5% of DM) and low or moderate DCAD (>-15.9 mEq/100 g), whereas greatest colostrum Brix % from older cows was associated with moderate DCAD (-15.9 to -8.0 mEq/100 g) and was not associated with starch (P=0.07).
Colostrum yield was not associated with prepartum glucose concentration or BCS, but greater yield was associated with prepartum NEFA ≥ 290 µEq/L compared with < 290 µEq/L. Colostrum Brix % was not associated with prepartum BCS glucose, or NEFA.
Some concluding comments mainly from the authors;
Colostrum yield from older cows was lower from cows fed diets with reduced DCAD (-7 vs. -18 mEq/100 g of DM although authors of other studies have reported no differences in colostrum yield when cows were fed DCAD +13 versus -13 and +12 versus -16.
In the current study, starch content was associated with colostrum yield.
Colostrum yield and Brix % were associated with the proportion of the diet in the top sieve of the Penn State Particle Separator (particle length ≥19 mm), used in this study as an indicator of long forage particles commonly observed in prepartum diets with greater inclusion of bulky forages.
In agreement with the current study, previous observational studies have not found an association between BCS and colostrum yield or quality.
Some limitations of this study per the authors were:
Sampling cows at a single time point 3 to 14 days before expected calving may have limited our ability to find such an association if present, between prepartum glucose concentration and colostrum Brix %.
The farms and sampled animals in this study population were a convenience sample. Given our study design and frequency of visits, short-term changes in diets or prevalence of hyperketonemia were not accounted for.
In addition, the administration of oxytocin to some cows at colostrum harvest, reported as a management strategy by 11 (57.9%) producers (Westhoff et al., 2023) was not accounted for as a potential confounding variable in the current analysis as we could not ascertain that individual cows did or did not receive oxytocin.
Nutrition and farm management were reflective of mid- to large-size New York dairy farms and caution should be taken when translating these results to farms with different management strategies.
The Bottom Line
“In this study, prepartum diets with CP 13.6 to 15.5% of DM and ≤ 13.5% of DM were associated with the greatest colostrum yield from older cows and first-calf heifers, respectively. Colostrum yield and Brix % were associated with prepartum NEFA concentration, diet components, and prevalence of hyperketonemia. Although other variables should be considered these data provide prepartum variables to consider when troubleshooting colostrum production on farms.”
Check out our interview with Dr. Kertz on this topic.
References
Kertz, A.F. 2023. Epidemiology of Colostrum in NY Holsteins. Feedstuffs 365, November 14, 2023.
Westhoff, T.A., S.J. Womack, T.R. Overton, C.M. Ryan, and S. Mann. 2023a.
Epidemiology of bovine colostrum production in New York Holstein herds: Cow, management, and environmental factors. J. Dairy Sci. 106:4874-4895.
Westhoff, T. A., T.R. Overton, and S. Mann. 2023b. Epidemiology of bovine colostrum production in New York Holstein herds: Prepartum nutrition and metabolic indicators. J. Dairy Sci. 106:4896-4905.
