Moisture content of high-straw dry cow diets affects intake, health, and performance of transition dairy cows

Abstract

The objective of this study was to determine the effect of adding water to a high-straw dry cow diet on feeding behavior, health, and performance of dairy cows. Holstein cows (n = 40) entering their second or greater lactation were enrolled at dry off (~45 d before expected calving) and assigned to 1 of 2 dietary treatments, consisting of a high-straw dry cow total mixed ration [TMR; 36% wheat straw, 41% corn silage, 23% pellet, on a dry matter (DM) basis, formulated for 11.6% crude protein, 1.35 Mcal/kg net energy for lactation] with (1) no water (CON; n = 20; DM = 53.4%) or (2) water added to decrease the DM by ~10 percentage points (wet diet, WD; n = 20; DM = 45.4%). Upon calving, all cows were fed the same lactating TMR (45.2% DM, 14.9% crude protein, 1.68 Mcal/kg net energy for lactation) and followed for 28 d. Dry matter intake, feeding behavior, and rumination activity were recorded automatically. Fresh TMR and orts samples were collected 2×/wk to determine differences in sorting. A particle separator was used to separate feed samples into 4 fractions: long (>19 mm), medium (<19, >8 mm), short (<8, >4 mm), and fine (<4 mm) particles. Feed sorting was calculated as actual intake of each particle fraction expressed as a % of predicted intake. Cows fed WD had greater DM intake during the dry period than cows fed CON (CON = 13.4 ± 0.24, WD = 14.2 ± 0.24 kg/d), but rumination did not differ (CON = 522.2 ± 8.48, WD = 518.5 ± 8.69 min/d) between treatments. Cows fed WD tended to consume their feed faster (CON = 0.08 ± 0.001, WD = 0.09 ± 0.001 kg of DM/min) compared with CON cows. Regardless of treatment, cows sorted against the longest ration particles, with cows fed CON sorting more against these (CON = 81.1 ± 2.51%, WD = 94.9 ± 2.58%). Cows fed CON tended to sort more in favor of the medium particles than those fed WD (CON = 105.0 ± 0.36%, WD = 104.2 ± 0.37%). Postcalving DM intake and feeding behavior were not affected by dry diet treatment. Cows fed WD experienced a less rapid daily decline in rumen pH during the first 7 d after calving compared with those fed the CON diet. The results suggest that increasing the moisture content of high-straw dry cow diets, by adding water, may improve intake and reduce sorting against the longest ration particles, which may help promote consistency in targeted nutrients consumed during the dry period and greater rumen health in early lactation.

Effects of molasses-based liquid feed supplementation to a high-straw dry cow diet on feed intake, health, and performance of dairy cows across the transition period

“…Cows will sort a diet where particle size is more easily distinguished (Oelker et al, 2009); as such, it may be possible that lactating cows in the Litherland et al (2013) study sorted more against the long particles because that diet contained a greater proportion of long particles on the top 2 screens as a result of liquid feed inclusion, making the long dietary particles in their diet more distinguishable. Interestingly, Havekes et al (2020b) reported a similar reduction, compared with the current study, in degree of sorting against the longest ration particles when water was added to a high-straw dry cow diet compared with when cows were fed a diet with no added water. It is noteworthy that the liquid feed addition in the current study did not drastically influence the overall DM content of the ration compared with that of the CON diet; accordingly, the observed results in this research are more likely related to non-moisture factors.…”

“…Forty Holstein cows (parity = 1.9 ± 1.04; mean ± SD) were used in this study, which took place at the University of Guelph Elora Research Station-Dairy Facility (Elora, ON, Canada). This study was performed in conjunction with the study described by Havekes et al (2020b), with both studies sharing the same group of control cows (n = 20). Cows were dried off and enrolled in the study at approximately 45 d before expected calving (actual = 43.2 ± 5.87 d).…”

“…That research demonstrated that using a smaller screen size (2.54-cm screen vs. 10.16-cm screen) to chop wheat straw in a highstraw (29%) dry diet increased DMI, reduced sorting, and improved metabolic health post-calving (Havekes et al, 2020a). Similarly, adding water to a high-straw dry diet (36% wheat straw), with straw chopped with a 2.54-cm screen, also increased DMI and reduced sorting during the dry period compared with the diet with no water added, and improved rumen pH around the time of calving (Havekes et al, 2020b). Despite reductions in sorting and improvements in DMI, approximately 5 to 10% refusals against the long forage particles still occurred in those studies, and cows still experienced a reduction in DMI as they approached calving.…”

Metabolic Stress in the Transition Period of Dairy Cows: Focusing on the Prepartum Period

“…Besides, the sorting behavior may persist in the fresh period with eventual negative consequences. Havekes et al [32][33][34] very recently proposed a variety of strategies to reduce the sorting behavior in low energy diets in the dry period. In a first experiment [32], they demonstrated that prepartum cows being fed a short chop length (2.54 cm screen) of wheat straw is preferable since it was associated with lower serum BHB concentration in the third week postpartum compared to that in cows fed a long chop length (10.16 cm screen) of wheat straw.…”

“…Although a shorter chop length of straw reduced sorting, it did not (completely) eliminate this behavior. In a next set of experiments, Havekes et al [33,34] moisturized the content of high-straw dry cow diets with water or liquid molasses. The hypothesis was that the addition of water to dry-cow diets that are low in moisture would improve DMI and reduce feed sorting, while the addition of liquid molasses will additionally support ruminal cellulolytic microbial growth.…”