Location: Dairy Forage Research
Project Number: 5090-31000-027-029-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Sep 1, 2023
End Date: Aug 31, 2024
Objective:
The objective of this research to compare three different increases in automatic milking system (AMS) pellet postpartum and then have pellet fed through the AMS at a flat feeding rate of 6 kg, or one of two progressive feed tables adjusted by milk volume or energy corrected milk. This will leverage the new capacity to conduct a novel AMS-nutrition experiment assessing the impact of precision feeding strategies on:
a) Lely performance data, milk composition and individual fatty acids, metabolic health monitoring
b) Blood biomarkers for nutrient partitioning (BUN, Glucose, NEFA), fecal and urine measurements and digestibility flows
c) GreenFeed measurements including methane, carbon dioxide, oxygen, and hydrogen.
Approach:
This project will take place at the Dairy Enterprise of Pioneer Farms using Holstein dairy cows (n = 144). Cows will be housed in a 50-cow free stall pen milked by an AMS (Lely A5) that is paired with a RIC2Discover feed intake system. Cows will be enrolled onto the experiment immediately after calving on a rolling basis and remain on study from 0 DIM to 119 DIM. To prevent overstocking of the 50-cow free stall pen, enrollment will be spread out across 15 mo with 18 cows enrolled every other month. Thus, the total projected timeline for conducting the cow experiment is 19 mo.
Prior to calving and enrollment, cows will be blocked based on parity, expected calving month, prepartum body condition score (BCS), and predicted transmitting ability for milk yield. Then, cows will be randomly assigned to treatments in a 3 × 3 × 2 factorial design (n = 8 cows per factorial) with the following treatment factors: pellet adaptation, feed table, and parity group. Pellet adaptation treatments will differ in the length of time postpartum that the cow will be provisioned AMS pellet at a low feeding rate (3 kg/d) prior to enrolling onto a feed table treatment. The three adaption treatment levels are 0 d, 7 d, and 14 d postpartum. Feed table treatments will differ in the in the strategy used to determine AMS pellet provision post-adaptation treatment. The three feed table treatments will include a static feeding rate (6 kg/d), a milk yield based progressive feeding rate, and an energy-corrected milk yield based progressive feeding rate. The progressive feeding rate treatments will be assessed twice weekly based on each individual cow, such that it occurs after routine measurements and samples (i.e. BCS, blood, and fecal). Parity group treatments will differ in cow parity number: primiparous vs multiparous cows. To simulate real-world conditions, all cows will be fed the same PMR ration formulated to meet the nutritional requirements of the average lactating cow when provisioned 6 kg of AMS pellet.
Cow bodyweight will be captured after every milk harvest by a weigh scale incorpAfter weekly blood samples will be collected by coccygeal vessle for blood metabolite determination. Included metabolites are: urea, glucose, insulin, non-esterified fatty acids beta-hydroxy butyrate, and creatinine. Weekly milk samples will be collected for the entire trial duration collected over two days. Milk samples will be analyzed for milk fat, true protein, lactose, solids non-fat, somatic cell count, and individual fatty acid analysis.
Every two weeks, fecal, and urine samples will be collected. Spot sample fecal samples will be collected via rectal palpitation four hours after feeding. Analysis of fecal samples will include: NDF, iNDF, starch, pH, N. Urine samples will be analyzed for uric acid, creatinine, and urinary urea nitrogen.
A GreenFeed unit will be installed in the feed alley and set to allow cows at set intervals. A target of 750 g of pelleted feed (same as fed through the AMS unit) will be supplied through the GreenFeed daily. Feed tables will be adjusted to offset for this intake.
