Effect of dry-off management on milking behavior, milk yield, and somatic cell count of dairy cows milked in automated milking systems

D.F Kelton,H.W Barkema,A.E France,T.J Devries,D Kurban,S Dufour

doi:10.3168/jds.2021-21383

D.F Kelton, H.W Barkema + Show 4 more

Open Access

https://doi.org/10.3168/jds.2021-21383

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Abstract

Milk production may be reduced before dry-off to decrease the risk of cows developing intramammary infections during the dry period. Such reductions in milk may be possible in automated milking systems (AMS) where milking frequency and feed allocation at the AMS can be controlled at the cow level. This study investigated the effect of dry-off management of cows milked in AMS on milk yield, milking behavior, and somatic cell count (SCC). Using a 2 × 2 factorial arrangement of treatments, applied from d 14 to 1 before dry-off, 445 cows from 5 commercial dairy farms in Quebec, Canada, were assigned within farm to either (1) reduced feed [RF; allowed a maximum of 0.75 kg/d of AMS pellet for the first week (14 to 8 d before dry-off) of treatment, and 0.50 kg/d for the second week (7 to 1 d before dry-off) of treatment], or (2) nonreduced feed (NF; allowed up to 2 kg/d of AMS pellet), and either (1) reduced milking (RM; reduced to 2 milkings/d or as many times as required to yield 17 kg/milking), or (2) nonreduced milking (NM; allowed up to 6 AMS milkings/d) and no maximum production. Feed and milking behavior data, as well as milk yield and SCC were collected from the AMS software. The RF cows had lower AMS feed delivered during the treatment period, as per the experimental design. Across the treatment period, the NF-NM cows had the highest milking frequency (2.7 times/d), followed by the RF-NM cows (2.4 times/d), and then both of the RM groups (1.8 times/d), which did not differ from each other. All cows, except the NF-NM cows, were gradually milked less frequently as dry-off approached. Across the entire 2-wk treatment period before dry-off, cows with RM allowance experienced a higher reduction in milk yield compared with the cows with no milking allowance restrictions (-4.8 vs. -3.6 kg). Similarly, cows with a RF allocation tended to have a higher reduction in milk yield than cows with NF (-4.6 vs. -3.7 kg). As result, those cows with both reduced milking permissions and feed allocation at the AMS experienced the greatest drop in milk production before dry-off. There were no differences between treatments for milking frequency or yield in the next lactation. Somatic cell score (calculated from SCC) was not different between treatments in the 2-wk or day before dry-off, nor in the first month after calving. Overall, these data suggest that reducing both milking frequency and feed quantity in the AMS is the most efficient method to decrease milk yield before dry-off, without negatively influencing milking frequency or yield in the next lactation, as well as without affecting milk quality.

Highlights

From the weeks after dry-off, when the mammary gland undergoes involution, to the onset of the lactation with the proliferation of mammary epithelial cells and milk production, the cow is most susceptible to the occurrence of new IMI (Bradley and Green, 2004)
The objective of this study was to determine how milking behavior, milk production, and somatic cell count (SCC) of dairy cows milked with an automated milking systems (AMS) are altered in response to changes in quantities of AMS pellet allocation and number of milkings allowed per day in the weeks leading up to dry-off
Analyses were conducted to test the effects of the feeding (RF vs. nonreduced feed (NF)) and milking (RM vs. nonreduced milking (NM)) treatments, and their interaction on each of the outcome variables: milk yield, milking frequency, failures, refusals, and SCS

Summary

Introduction

From the weeks after dry-off, when the mammary gland undergoes involution, to the onset of the lactation with the proliferation of mammary epithelial cells and milk production, the cow is most susceptible to the occurrence of new IMI (Bradley and Green, 2004). In no study to date have any negative effects been demonstrated for reducing milking from 2 times/d to 1 time/d (Tucker et al, 2007, 2009) on cow health and behavior, implying that the benefits of reducing milk production before dry-off through reducing milking frequency is more beneficial than harmful. Another method to reduce milk yield before dry-off is to reduce dietary nutrient intake, ideally without inducing any level of hunger in cows, which could negatively affect cow welfare (Zobel et al, 2015)

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