Effects of prepartum supplementation of β-carotene in Holstein cows

Resveratrol supplementation improves productivity and health in heat-stressed lactating Holstein cows

Heat stress impairs production performance and thermal homeostasis in lactating dairy cows. Despite the use of on-farm heat abatement systems, milk production and wellbeing remain suboptimal during spring and summer in North America. Resveratrol, a plant-based polyphenolic compound, prevents inflammation and may protect cattle against the pathological effects of heat stress. We hypothesized that resveratrol supplementation would improve thermal homeostasis and productivity in heat-stressed dairy cows. A study was designed to establish the effects of resveratrol supplementation on lactating cows exposed to ambient temperature and relative humidity commonly observed in dairy herds in the Southeastern United States during summer. First, second, and third or greater lactation (n = 14, n = 11, and n = 23) Holstein cows averaging (±SD) 41.0 ± 3.9 kg/d, 53.8 ± 6.0 kg/d, and 52.5 ± 8.8 kg/d of milk yield were housed in a sand-bedded freestall barn at the University of Tennessee (Walland, TN) farm in June 2022. Cows were fed a common diet during a baseline period of 1 wk, followed by an adaptation period of 2 wk, and a treatment period of 3 wk. Cows were assigned to either the control group (CON, n = 24, no administration of resveratrol) or the resveratrol group (RES, n = 24, 0.5 g/d of resveratrol) during the adaptation and treatment periods. Resveratrol was administered to each individual cow in the RES group in the morning feeding. During the treatment period, cows did not receive heat abatement from sprinklers and fans. Rectal temperatures (RT) and respiratory rates (RR) were recorded thrice daily. Milking occurred twice daily, and milk samples were collected at 2 consecutive milkings twice weekly. Blood samples were collected once a week to determine plasma cytokine concentrations, and fecal samples were collected once a week to determine water content. Body weights were recorded twice weekly. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Fixed effects included main effects of treatment, parity, day, time, and all possible interactions with day and time as repeated measures, and animal was included as a random effect. The autoregressive structure was used based on the lower Akaike and Bayesian information criteria. Baseline measurements were collected and included in the model as covariates. Regression analyses were used to determine the relationships of milk production with minimum and average temperature-heat index (THI) and milk production values with RT. During the treatment period, cows experienced a daily increment in ambient temperature from 21 to 31°C, and the mean THI was >72. Compared with CON cows, RES cows showed increased production of milk (35.1 ± 0.5 vs. 34.4 ± 0.3 kg/d), lactose (1.66 ± 0.02 vs. 1.60 ± 0.01 kg/d), and protein (0.94 ± 0.01 vs. 0.90 ± 0.01 kg/d). Compared with CON, RES treatment reduced RT at noon (treatment × time interaction) and on d 9, 11, 12, 15, and 18 (treatment × day interaction). The RR increased in RES cows, and this effect was more prominent in parity ≥3 cows. The relationship between milk yield and maximum RT indicated that the decline in milk yield was lower in RES than in CON heat-stressed cows. The BW increased in parity 1 cows treated with RES (638 ± 6 vs. 607 ± 6 kg). Fecal moisture content was greater in RES than in CON animals. In summary, resveratrol improves production and wellbeing in heat-stressed lactating Holstein cows. Polyphenolic compounds may be useful feed additives to reduce detrimental effects of heat stress on commercial operations.

Effects of postbiotic products from Saccharomyces cerevisiae fermentation on lactation performance, antioxidant capacity, and blood immunity in transition dairy cows

This study aimed to evaluate the effects of dietary supplementation with different types of Saccharomyces cerevisiae fermentation products (SCFP) on lactational performance, metabolism, acute phase protein response, and antioxidant capacity in dairy cows from -21 to 56 DIM. A total of 180 multiparous Holstein dairy cows were blocked by parity, expected calving date, pre-trial BCS, and previous 305-d mature-equivalent milk yield, and then randomly assigned to 1 of 3 dietary treatments: the basal control diet (CON; n = 60), the basal diet supplemented with 40 g/d of XPC (XPC; n = 60; Diamond V, Cedar Rapids, IA), and the basal diet supplemented with 19 g/d of NutriTek (NTK; n = 60, Diamond V). Blood (n = 15, 13, and 12 in the CON, XPC, and NTK groups, respectively) was sampled at -7 (± 3), +3, +7, +21, and +28 d, and milk (n = 19, 18, and 15 in the CON, XPC, and NTK groups, respectively) was sampled from 1 to 8 wk from a subset of cows from -21 to 56 d relative to calving. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). All data were subjected to repeated measures ANOVA. Dietary treatment (Trt), time, and their interaction (Trt × time) were considered as fixed effects and cow as the random effect. Cows fed XPC and NTK had greater ECM yield. Supplementing NTK increased milk fat content and yield and 3.5% FCM yield compared with CON. Milk urea nitrogen was lower in XPC cows than CON. We found that SCFP supplementation decreased plasma BHB, ceruloplasmin, haptoglobin (HPT), and IL-1β concentrations, and it increased plasma P concentrations. In addition, cows fed NTK showed lower creatinine (CR) and cortisol concentrations but increased plasma Ca and myeloperoxidase concentrations than CON cows. In addition, cows fed NTK and XPC both had reduced plasma concentrations of serum amyloid-A (SAA) at 3 DIM compared with CON cows. Furthermore, SCFP cows had greater concentrations of plasma glucose and Ca than CON cows at 7 DIM, and greater concentrations of plasma P at 21 DIM. Between the groups fed different types of SCFP, plasma concentrations of nonesterified fatty acids, malondialdehyde, CR, SAA, and HPT were lower in cows fed NTK compared with cows fed XPC at 7 DIM. Overall, our results indicate the potential benefits of supplementing SCFP in transition dairy cows by modulating immunity and liver metabolic function and supporting ECM yield. The results also suggest that NutriTek at 19 g/d appears to support the performance and health of dairy cows better compared with XPC at 40 g/d, based on improved metabolic and inflammatory status during the transition period.

The Efficacy of β-Carotene in Cow Reproduction: A Review

β-carotene supplementation improves the reproductive performance of cattle. However, the research results on this topic have been inconsistent, and no clear conclusion has been reached. In previous reviews of this topic, the functional mechanism of β-carotene in reproduction remained unclear, but subsequent studies have shown that the antioxidant effects of β-carotene protect enzymes involved in ovarian sex steroid hormone production from the effects of oxygen radicals. This role consequently affects normal ovarian follicle dynamics, maintenance of luteal function, and the estrous cycle, and indirectly improves reproductive performance by preventing perinatal diseases and facilitating recovery from these diseases. Several factors must be considered in feeding management to determine whether β-carotene supplementation is effective for improving reproductive performance in cows. The same is true when the animal consumes a large amount of the antioxidant β-carotene due to lactation, aging, or season. Therefore, it is important to consider the balance between the supply and consumption of β-carotene and evaluate whether β-carotene supplementation has an effect on reproductive performance in cows.

The role of beta-carotene in cattle infertility, mastitis and milk yield: A systematic review and meta-analysis

The impact of beta-carotene on cattle fertility has been investigated in various studies; however, consensus on this issue has not been reached. In the present study, we systematically reviewed and meta-analysed 29 publications conducted between 1984 and 2022, focusing on seven fertility measures, clinical mastitis and milk yield in cows. We did not find statistically significant results in 8 out of 11 parameters (p > .05). Statistically significant results were observed for milk yield (MD: 216.25 kg in 305 days, p = .01, CI: 50.73-381.77), pregnancy at first service (OR: 1.38 CI: 1.08-1.76, p = .01) and clinical mastitis (OR: 0.59, CI: 0.44-0.80, p = .006) in favour of beta-carotene supplementation. The meta-regression revealed significant effects of 'plasma beta-carotene levels' on 'service to per pregnancy' and dose on 'milk yield' (p = .04 and p = 0). In binary outcomes, 'dose × day' and 'plasma beta-carotene concentration in the control group' positively influenced pregnancy at first service (p = .02 and .03). In conclusion, given the positive point direction observed for some variables and insignificant results for others, there is a need for more studies. We note the very high heterogeneity of outcomes and suggest caution in interpreting results.

Effects of prepartum supplementation of β-carotene on colostrum and calves

Little is known about transfer of dietary β-carotene into colostrum, its absorption by the calf, and its effects on retinol and α-tocopherol in the calf when the dam's dietary vitamin A is adequate. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period on the colostrum and calf. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were blocked by calving data, parity, and previous production, and then randomly assigned to either control or β-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, DSM Nutritional Products, 8 g/d; provided 800 mg β-carotene) or carrier from 21 d before expected calving until calving. Colostrum was collected within 2 h of parturition. Calf blood samples were obtained within 2 h of birth before receiving the dam's colostrum, at 24 h after birth, and at 7 d and 60 d of age. Blood serum was analyzed for β-carotene, retinol, α-tocopherol, and other metabolites and enzymes. Colostrum was analyzed for β-carotene, retinol, α-tocopherol, colorimetry profile, and milk components. Data were analyzed using mixed-effects models in SAS (SAS Institute Inc.). Calf serum β-carotene data were analyzed using the FREQ procedure. Colostrum β-carotene was higher for BC cows. Colostrum from BC cows had increased a* [measures red (positive) to green (negative)] and b* [measures yellow (positive) to blue (negative)] colorimeter values, indicating that β-carotene altered colostrum color toward red and yellow. Supplementation did not affect colostral or calf IgG concentrations. Colostrum color indices were correlated with IgG concentrations as well as concentrations of β-carotene, retinol, and α-tocopherol. Before receiving colostrum, the concentration of β-carotene in calf serum was below the detectable threshold of 0.05 μg/mL. At 24 h of age, the number of calves with detectable β-carotene concentrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from cows in the control group (6.1%). No differences in concentrations of retinol or α-tocopherol were observed in calf serum. Supplementation of β-carotene to cows decreased activities of gamma-glutamyl transpeptidase and glutamate dehydrogenase in calf serum. In pregnant cows already receiving adequate vitamin A, supplementation of β-carotene increased concentration of β-carotene in colostrum, altered colostrum color, and increased serum β-carotene in calves at birth.