Fertility and milk production on commercial dairy farms with customized lactation lengths

Abstract

Drying-off, calving, and start of lactation are critical transition events for a dairy cow. As a consequence, most animal health issues occur during these periods. By extending the voluntary waiting period for first insemination after calving, calving interval (CInt) can be extended, with possible positive effects for fertility and health. Some cows might be better suited for an extended CInt than others, due to differences in milk yield level, lactation persistency, or health status, which would justify a customized CInt based on individual cow characteristics. This study aims to investigate 13 farms with customized CInt, with respect to calving to first service interval (CFSI), accomplished CInt, services per conception (SC), conception rate at first artificial insemination (CR1AI), peak yield, lactation persistency, 305-d yield, and effective lactation yield. In total, 4,858 complete lactations of Holstein Friesian cows between 2014 and 2019 from the 13 farms were grouped by parity (1 or 2+) and CFSI (CFSI class; CFSI-1 < 84; 84 ≤ CFSI-2 < 140; 140 ≤ CFSI-3 < 196; 196 ≤ CFSI-4 < 252, CFSI-5 ≥ 252 d) or CInt (CInt class; CInt-1 < 364; 364 ≤ CInt-2 < 420; 420 ≤ CInt-3 < 476; 476 ≤ CInt-4 < 532, CInt-5 ≥ 532 d). Cow inseminations, available for 11 out of 13 farms (3,597 complete lactations), were grouped by parity (1 and 2+) and CFSI class or CInt class. The fertility and milk production characteristics were analyzed with generalized and general linear mixed models. The CFSI class was not associated with SC, but extended CInt class was associated with increased SC . More than 50% of cows in the CFSI class <84 d ended up in longer than expected CInt (>364 d), showing that these cows were not able to conceive for the desired CInt. More than 50% of cows in CInt classes 3 and higher (CInt ≥ 420 d) had an earlier first insemination before successful insemination (CFSI class 1; <196 d), showing that these extended CInt classes consisted of both cows with an extended waiting period for first insemination and cows that failed to conceive at earlier insemination(s). On most farms, lactation persistency was greatest in CInt class 1 (<364 d), probably related to the low peak yield in this class. When this shortest CInt class was excluded, persistency increased with extended CInt classes on most farms. Although at the majority of farms 305-d yield was greater in CInt ≥ 532 d, effective lactation yield at most farms was greatest in CInt from 364 to 531 d, especially for multiparous cows. Based on the results of this study, a CInt between 364 and 531 days seems most optimal for milk production, when high-yielding cows were selected.

Effects of extended voluntary waiting period from calving until first insemination on body condition, milk yield, and lactation persistency

“…The reason for the lower production of multiparous cows in VWP200 could be that they have more days at the end of this long lactation, where milk yield is usually lower. Also, in our earlier study at commercial farms, cows with the greatest production potential that had calving intervals >531 d could not sustain production in these long CInt (Burgers et al, 2021). In that study, however, the long CInt consisted of both cows with a voluntarily extended waiting period for insemination and cows that failed to conceive at earlier insemination(s).…”

“…In the current study, we investigated the effects of 3 VWP on milk yield and lactation persistency in a controlled experiment, in contrast with the work on extended lactations that is performed in observational studies on farms (e.g., Lehmann et al, 2016;Mellado et al, 2016;Burgers et al, 2021). All cows were blocked and randomly assigned to one of the 3 VWP groups, which had a fixed VWP in days, making it possible to find cow characteristics that contribute to milk yield of individual cows in different lactation lengths.…”

“…Selecting specific cows for extended VWP could imply that herd-level benefits of longer CInt, such as reduced frequency of transitions such as dry-off and calving, reduced labor related to these transitions and reduced the number of surplus calves, as well as minimizing loss of milk yield on a herd level. Some farmers already used different cow characteristics in early lactation to determine for which cows they extended the VWP (Lehmann et al, 2016;Burgers et al, 2021). Early-lactation characteristics that were used in our earlier study included maximum yield, BCS, and BW (Burgers et al, 2021).…”

“…Some farmers already used different cow characteristics in early lactation to determine for which cows they extended the VWP (Lehmann et al, 2016;Burgers et al, 2021). Early-lactation characteristics that were used in our earlier study included maximum yield, BCS, and BW (Burgers et al, 2021). In practice, farmers often extended VWP until cows reached a certain milk level (Burgers et al, 2021).…”

“…Early-lactation characteristics that were used in our earlier study included maximum yield, BCS, and BW (Burgers et al, 2021). In practice, farmers often extended VWP until cows reached a certain milk level (Burgers et al, 2021). Waiting until milk drops below a certain level helps in selecting more persistent cows for longer CInt, as the longer a cow takes to reach this milk level, the longer the VWP will be, and often the more persistent this cow is.…”