Do biological and management reasons for a short or long dry period induce the same effects on dairy cattle productivity?

Abstract

The dry period is a well-established factor that determines lactation success. A retrospective observational study used 32,182 lactations from 16 farms to determine whether management versus biological reasons for deviations from the targeted 60-d dry period have the same associations with subsequent lactation performance. Herd inclusion criteria were Holstein cows, herd size ≥900 cows, breeding by artificial insemination, and (minimally) bimonthly milk testing. Dry period length (DPL) and gestation length (GL) were each categorized as short [>1 standard deviation (SD) below mean within herd; means 45 d DPL, 269 d GL] or long (>1 SD above mean within herd; means 73 d DPL, 284 d GL) and combined to generate the following 7 study groups: short DPL, short GL (S D S G , n = 2,123); short DPL, average GL (S D A G , n = 1,418); average DPL, short GL (A D S G , n = 1,759); average DPL, average GL (A D A G , n = 19,265); average DPL, long GL (A D L G , n = 3,325); long DPL, average GL (L D A G , n = 2,573); and long DPL, long GL (L D L G , n = 1,719). Responses evaluated included milk and component yields at first test and over the whole lactation, days to first service, first service conception risk, days open, and herd retention through 60 and 365 d postpartum. Continuous data were analyzed by mixed models and time to event data by Cox proportional hazard models, both accounting for clustering at the herd level. First test and whole-lactation milk and component yields were lowest for S D S G . Within cows that experienced calving difficulty, rates of receiving first service were 13 and 20%

Association between Prepartum Alerts Generated Using a Commercial Monitoring System and Health and Production Outcomes in Multiparous Dairy Cows in Five UK Herds

“…A difference in treatment incidence was observed between farms which may reflect differences in management systems and other areas influencing disease which were not addressed by this study. These factors induce social stress and alter the risk of disease [45,53,54]. It is also possible that differences arose due to differences in recording practices, and interpretation and classification of clinical signs [47] between herds although the overall incidence of treatments found in this study is in keeping with findings elsewhere [20,55].…”

Association of days in close up, gestation length, and rumination around time of calving with disease and pregnancy outcomes in multiparous dairy cows

“…It might also be expected, as shown in this study, that there would initially be a positive relationship between PC1 and reduction in the likelihood of disease in early lactation but that this relationship would weaken and fall away as an optimum is reached, allowing the majority of cows to adequately acclimatize to a new social ranking following a group change. As DCU is a component of the total dry period length, we speculate that the increase in the odds of disease observed in this study as PC1 increased beyond an optimum can be explained by an increase in DCU contributing to an increase in total dry period length, which has been shown to be detrimental to health (Dann et al, 2006;Pinedo et al, 2011) and production (Olagaray et al, 2020). Possible mechanisms for this effect could include simple under-or overfeeding (Dann et al, 2006) as well as changes in insulin sensitivity induced by prolonged feeding of acidogenic diets, which favor a more lipolytic state, potentially detrimental to health (Vieira-Neto et al, 2021).…”

“…Newly introduced cows must establish a ranking in the group, and it appears reasonable that a longer stay in a precalving or close-up group may be more beneficial than a shorter stay (Robinson et al, 2001;Nordlund et al, 2006). More recently, gestation length (GL; Vieira-Neto et al, 2017) and deviations in dry period length (Olagaray et al, 2020) have been shown to influence health and performance in dairy cows. Shortened dry periods occurring for biological reasons had a greater negative effect than those occurring for management reasons, whereas lengthened dry periods occurring for management reasons had a greater negative effect.…”

“…The negative effect of a shortened dry period occurring due to a shortened GL is likely to be a response to physiological stressors, such as cows carrying twins or being subjected to heat stress in late pregnancy, that also lead to impaired health and milk production. A lengthened dry period will carry an increased risk of excessive body condition and a metabolic scenario associated with poor DMI that would lead to an increased risk of metabolic disease in early lactation (Olagaray et al, 2020). Clearly, the effects of the number of days spent in close up (DCU) may be confounded by GL, as cows with shorter gestations are likely to experience less DCU and vice versa.…”

Effects of limits in milking capacity, housing capacity, or fat quota on economic optimization of dry period lengths

“…However, longer DPL may also be motivated by a risk analysis, for example because the date of calving is unknown. Earlier than expected calving may lead to large reductions in the cow's performance in the subsequent parity, especially when dry cows are not managed for short DPL, such as with feeding appropriate dry cow rations (Olagaray et al, 2020). Therefore, longer DPL than found to be optimal in our study are not irrational.…”