of subclinical mastitis during early lactation and effects of subclinical
mastitis on milk yield, lamb growth, and lamb survival
To date, we have completed all sample collections, milk component analysis, and preliminary milk production and lamb performance statistical analysis.
Accomplishment/Activity Relevance to Objective
1 - Lambed out 45 ewes during April 2021. Collected milk samples for future microbial
DNA extraction, milk components (e.g., fat, protein, lactose, solids, etc.), and yield on d 1, 7, 14, 21, 28, 35, 42, 49, 56, and 63 post parturition, along with ewe and lamb body
ewe back fat depth. Collected ewe feces on d 1 post-parturition. Collected
lamb rumen fluid on day 7, 28, and 63. Measured litter creep feed intake
from day 28 through 63 when lambs were weaned.
All samples associated with future laboratory work have been collected.
Challenge or Development Corrective Action or Project Change
1 - The mitigation of mastitis during early lactation was removed as a study component.
focus was placed on quantifying the prevalence of subclinical mastitis
throughout the entire lactation.
2 - How to measure milk yield to accurately represent daily milk yield without impacting
ewe and lamb behavior and performance. Many things can influence milk yield that we
tried to account for by leaving the building lights on, milking ewes in the same environment where they could see their lambs on the other side of the gates, consistent
3 - How to measure creep feed intake. The more experimental units that observations
can be observed for, the more likely to observe statistical significance. Rather than
measuring group intake from 4 or 5 group pens, we measured creep intake for each
(single or twin-reared lambs). This was labor-intensive setting up more than
40 individual pens to keep the ewe and her lambs with creep feeding areas
and required daily manual removal of soiled bedding.
and Indicator Results to Date
Outcome/Indicator Quantifiable Results
1 - Milk
yield Estimated daily milk yields were measured weekly and adjusted to
assume equal production of both udder halves for a 24- hour period.
2 - Milk components and somatic cell count Each milk sample was sent to a Dairy Herd
Association certified commercial laboratory to measure somatic cell count,
milk fat, protein, lactose, ureanitrogen, other solids, and total solids.
Preliminary analysis of quantitative data, including identifying
correlations and linear regressions of somatic cell count, milk yield and
components, creep feed intake, litter size, day of lactation, back fat
depth, and ewe/lamb body weight gain/loss.
2 - Extend the hiring of an undergraduate researcher through Summer 2022 who helped collect these samples to begin microbial DNA extraction of milk samples. To maximize cost effectiveness, these samples will be collected from the extreme somatic cell counts
(lowest average, median average, highest average; least and most weekly fluctuation)