A mycotoxin-deactivating feed additive counteracts the adverse effects of regular levels of Fusarium mycotoxins in dairy cows

Little is known about the effects of commonly found levels of Fusarium mycotoxins on the performance, metabolism, and immunity of dairy cattle. We investigated the effects of regular contamination levels, meaning contamination levels that can be commonly detected in dairy feeds, of deoxynivalenol (DON) and fumonisins (FB) in total mixed ration (TMR) on the performance, diet digestibility, milk quality, and plasma liver enzymes in dairy cows. This trial examined 12 lactating Holstein dairy cows using a 3-period × 3-treatment Latin square design. The experimental period was 21 d of mycotoxin exposure followed by 14 d of washout. During treatment periods, cows received one of 3 diets: (1) CTR (control) diet of TMR contaminated with 340.5 µg of DON/kg of dry matter (DM) and 127.9 µg FB/kg of DM; (2) MTX diet of TMR contaminated with Fusarium mycotoxins at levels higher than CTR but below US and European Union guidelines (i.e., 733.0 µg of DON/kg of DM and 994.4 µg of FB/kg of DM); or (3) MDP diet, which was MTX diet supplemented with a mycotoxin deactivator product (i.e., 897.3 µg of DON/kg of DM and 1,247.1 µg of FB/kg of DM; Mycofix, 35 g/animal per day). During washout, all animals were fed the same CTR diet. Body weight, body condition score, DM intake, dietary nutrient digestibility, milk production, milk composition and rennet coagulation properties, somatic cell count, blood serum chemistry, hematology, serum immunoglobulin concentrations, and expression of multiple genes in circulating leucocytes were measured. Milk production was significantly greater in the CTR group (37.73 kg/d) than in the MTX (36.39 kg/d) and the MDP (36.55 kg/d) groups. Curd firmness and curd firming time were negatively affected by the MTX diet compared with the other 2 diets. Furthermore, DM and neutral detergent fiber digestibility were lower after the MTX diet than after the CTR diet (67.3 vs. 71.0% and 42.8 vs. 52.3%). The MDP diet had the highest digestibility coefficients for DM (72.4%) and neutral detergent fiber (53.6%) compared with the other 2 diets. The activities of plasma liver transaminases were higher after the MTX diet than after the CTR and MDP diets. Compared with the CTR diet, the MTX diet led to slightly lower expression of genes related to immune and inflammatory functions, indicating that Fusarium mycotoxins had an immunosuppressive effect. Our results indicated that feed contaminated with regular levels of Fusarium mycotoxins adversely affected the performance, milk quality, diet digestibility, metabolic variables, and immunity of dairy cows, and that supplementation with mycotoxin deactivator product counteracted most of these negative effects.

Effect of hot season on blood parameters, fecal fermentative parameters, and occurrence of Clostridium tyrobutyricum spores in feces of lactating dairy cows

High temperature influences rumen and gut health, passage rate, and diet digestibility, with effects on fermentative processes. The main aim of the study was to investigate the effect of hot season on hindgut fermentation, the occurrence of Clostridium tyrobutyricum spores in bovine feces, and on their relationship with metabolic conditions in dairy cows producing milk used for Grana Padano cheese. The study was carried out on 7 dairy farms located in the Po Valley (Italy), involving 1,950 Italian Friesian dairy cows. The study was carried out from November 2013 till the end of July 2014. Temperature and relative humidity were recorded daily by weather stations. Constant management conditions were maintained during the experimental period. Feed and diet characteristics, metabolic conditions, and fecal characteristics were recorded in winter (from late November 2013 to the end of January 2014), spring (from April to May 2014), and summer (July 2014) season. In each season, blood samples were collected from 14 multiparous lactating dairy cows per herd to measure biochemical indices related to energy, protein, and mineral metabolism, as well as markers of inflammation and some enzyme activities. Fecal samples were also collected and measurements of moisture, pH and volatile fatty acids (VFA) were performed. The DNA extracted and purified from fecal samples was used to detect Clostridium tyrobutyricum spores in a quantitative real-time PCR assay. The daily mean temperature-humidity index was 40.7 ± 4.6 (range 25 to 55), 61.2 ± 3.7 (range 39 to 77), and 70.8 ± 3.2 (range 54 to 83) in winter, spring, and summer, respectively. Total VFA concentration in feces progressively decreased from winter to summer. The seasonal changes of acetate and propionate followed the same trend of total VFA; conversely, butyrate did not show any difference between seasons, and its molar proportion was greater in summer compared with winter. A greater occurrence of Cl. tyrobutyricum spores in summer compared with the other seasons was observed. The plasma concentrations of glucose, urea, albumin, Ca, Mg, Cl, Zn, and alkaline phosphatase activity were lower in summer compared with winter, whereas the opposite occurred for bilirubin and Na. Our results show that summer season, through direct and indirect effect of heat stress, affected fecal fermentative parameters and hindgut buffering capacity, and was responsible for the increasing occurrence of Cl. tyrobutyricum spores in feces.

Selection for milk coagulation properties predicted by Fourier transform infrared spectroscopy in the Italian Holstein-Friesian breed

Milk coagulation is based on a series of physicochemical changes at the casein micelle level, resulting in formation of a gel. Milk coagulation properties (MCP) are relevant for cheese quality and yield, important factors for the dairy industry. They are also evaluated in herd bulk milk to reward or penalize producers of Protected Designation of Origin cheeses. The economic importance of improving MCP justifies the need to account for this trait in the selection process. A pilot study was carried out to determine the feasibility of including MCP in the selection schemes of the Italian Holstein. The MCP were predicted in 1,055 individual milk samples collected in 16 herds (66 ± 24 cows per herd) located in Brescia province (northeastern Italy) by means of Fourier transform infrared (FTIR) spectroscopy. The coefficient of determination of prediction models indicated moderate predictions for milk rennet coagulation time (RCT=0.65) and curd firmness (a₃₀=0.68), and poor predictions for curd-firming time (k₂₀=0.49), whereas the range error ratio (8.9, 6.9, and 9.5 for RCT, k₂₀, and a₃₀, respectively) indicated good practical utility of the predictive models for all parameters. Milk proteins were genotyped and casein haplotypes (αS₁-, β-, αS₂-, and κ-casein) were reconstructed. Data from 51 half-sib families (19.9 ± 16.4 daughters per sire) were analyzed by an animal model to estimate (1) the genetic parameters of predicted RCT, k₂₀, and a₃₀; (2) the breeding values for these predicted clotting variables; and (3) the effect of milk protein genotypes and casein haplotypes on predicted MCP (pMCP). This is the first study to estimate both genetic parameters and breeding values of pMCP, together with the effects of milk protein genotypes and casein haplotypes, that also considered k₂₀, probably the most important parameter for the dairy industry (because it indicates the time for the beginning of curd-cutting). Heritability of predicted RCT (0.26) and k₂₀ (0.31) were close to the average heritability described in literature, whereas the heritability of a₃₀ was higher (0.52 vs. 0.27). The effects of milk proteins were statistically significant and similar to those obtained on measured MCP. In particular, haplotypes including uncommon variants showed positive (B-I-A-B) or negative (B-A(1)-A-E) effects. Based on these findings, FTIR spectroscopy-pMCP is proposed as a potential selection criterion for the Italian Holstein.

Can a single rumen sample really diagnose SARA in commercial farms?

The accuracy of diagnosis of subacute rumen acidosis (SARA) with a single measurement of the ruminal pH remains contradictory. To clarify this aspect, a large assessment of rumen, faecal and blood parameters was performed in several herds characterised by diets rich in non-structural carbohydrates. Rumen fluid was collected by rumenocentesis 6 h after feeding from 114 dairy cows (half 30–90 and half 150–250 days in milk) from 10 herds. In the same day, blood and faecal samples were collected and milk yield was recorded. The herds were ex-post classified as healthy (CTR n = 6) or as at risk for SARA (n = 4), based on ruminal pH. SARA versus CTR herds had lower rumen pH (5.67 vs 5.97 P < 0.01) and higher concentration of VFA, with lower acetate (P < 0.01) and higher propionate and valerate (P < 0.05) proportions. Moreover, the faecal DM was lower (P < 0.05), whereas the milk yield was higher with a lower concentration of fat (P < 0.05). At blood level, no significant differences were observed between the groups on positive acute-phase proteins, whereas SARA herds showed higher concentrations of paraoxonase and Ca and lower of cholesterol, total proteins, nitrates, Na and Zn (P < 0.01). Therefore, SARA herds did not show any evident symptom of ruminal disorder or systemic inflammation. On the contrary, these herds had a higher milk yield and a better inflammometabolic profile. These data confirm the difficulties to diagnose the SARA by a single measurement of ruminal pH in commercial herds and suggest the need of more specific indices to identify herds at risk.

Estimation of dry matter intake by n-alkanes in dairy cows fed TMR: effect of dosing technique and faecal collection time

Estimation of individual intakes in dairy cows would be beneficial to select animals according to efficiency of milk production. The n-alkanes technique has been used to estimate intake by dairy cows in free stall barns, limiting faecal samples to one or two per day, but diurnal variation in the ratio of dosed to natural alkanes in faeces represents a source of error. We aimed to adapt this technique to estimate feed intake on a large number of lactating dairy cows housed on commercial dairy farms. Using a change-over design, six lactating cows fed a TMR diet were given a dose of 0.5 g/day of C32 n-alkane administered once a day as a drench (DRE) or top fed (TP). Feed offered and refused were weighed daily. After the lead-in phases, faeces were collected at 0700 hours, 1400 hours and 1900 hours on the last 5 days of each dosing period. Dry matter intake (DMI) was estimated from C31, C33 and C32 concentrations in feeds and in faeces for each dosing system and sampling time. DMI estimated from C31 : C32 ratio was better correlated with measured individual DMI than estimates from C33 : C32 ratio. For DRE, the best correlation was for sampling at 1400 hours (R2 = 0.96, P < 0.001), but estimated DMI for the 1400 hours sampling was much higher than the actual DMI. For TP, the best correlation was for sampling at 0700 hours (R2 = 0.83, P < 0.001). Feeding C32 n-alkane and collecting faeces once a day at the same time (0700 hours) represents a valuable protocol to measure individual intake on a large number of animals.

Evaluation of innate immune responses in bovine forestomachs

Previous studies had indicated an active role of bovine forestomachs in the response to alimentary disorders as well as to inflammatory and infectious processes in both the gastro-intestinal (GI) tract and elsewhere. We investigated the potential of bovine forestomachs to receive, elaborate and produce signals and mediators of the innate immune response. Indeed, we detected the expression of Toll IL-1R8/single Ig IL-1-related receptor (TIR8/SIGIRR) and other receptors and cytokines, such as Toll-like receptor (TLR)4, interleukin (IL)-1β, IL-10 and Caspase-1 in the forestomach walls of healthy cows. Their presence suggests an active role of forestomachs in inflammatory disorders of the GI tract and other body compartments. Moreover, interferon (IFN)-γ was revealed in ruminal content. We confirmed and further characterized the presence of leukocytes in the rumen fluids. In particular, T-, B-lymphocytes and myeloid lineage cells were detected in the ruminal content of both rumen-fistulated heifers and diseased cows. An acidogenic diet based on daily supplements of maize was shown to inhibit leukocyte accumulation, as opposed to a control, hay-based diet, with or without a soy flour (protein) supplement. On the whole, results indicate that bovine forestomachs can receive and elaborate signals for the immune cells infiltrating the rumen content or other organs. Forestomachs can thus participate in a cross-talk with the lymphoid tissues in the oral cavity and promote regulatory actions at both regional and systemic levels; these might include the control of dry matter intake as a function of fundamental metabolic requirements of ruminants.

Influence of different periods of exposure to hot environment on rumen function and diet digestibility in sheep

Effects of different periods of exposure to hot environments on rumen function, diet digestibility and digesta passage rate were studied in four adult not-pregnant Sardinian ewes housed in a climatic chamber. The ewes were kept in individual metabolic cages. The trial lasted 83 days; 17 days were spent under thermal comfort conditions (TC) [temperature-humidity index (THI) = 65.0 +/- 2.0], followed by 49 days under elevated THI (ETHI: THI = 82.0 +/- 2.5) and 17 days under thermal comfort (TC; THI = 65.0 +/- 1.0). Five digestibility and passage rate trials were carried out during the 83 days. Trials 1 and 5 were carried out under TC; trials 2, 3 and 4 were carried out under ETHI. Values of rectal temperatures (39.7 +/- 0.3 degrees C) and respiratory rate (118.4 +/- 31.8 breaths/min) indicated that sheep under ETHI were heat-stressed. Heat stress caused an increase (P < 0.01) in water intake, and reductions (P < 0.05) in dry matter intake, rumen pH, rumen cellulolytic and amylolytic bacteria count, rumen osmolarity, organic matter, dry matter, neutral detergent fibre, acid detergent fibre and non-structural carbohydrates digestibility coefficients, and a reduction of digesta passage rates. Under ETHI, diet digestibility and passage rate of digesta were reduced in a time-dependent fashion. Variation of diet digestibility under ETHI was not related to passage rate of digesta and feed intake. Reduction of cellulolytic and amylolytic bacteria and the adaptive response to hot environment seem to be related to alteration of digestibility observed in ewes chronically exposed to hot environment.

Influence of short- and long-term exposure to a hot environment on rumen passage rate and diet digestibility by Friesian heifers

Effects of short- and long-term exposure to a hot environment on diet digestibility and rumen passage rate were studied in four, 10-mo-old Friesian heifers housed in a climatic chamber. The trial lasted 65 d. Twenty-five days were spent under thermal comfort (temperature-humidity index = 64), and 40 d were spent under hot conditions (temperature-humidity index = 84). Three digestibility and rumen passage rate trials were performed during the 65 d. Chromium oxide was used as an external marker. The first digestibility and rumen passage rate trial (trial 1) was performed under thermal comfort; trials 2 and 3 were performed under hot conditions. Exposure to the hot environment reduced dry matter intake and increased water intake and rectal temperature compared with those during the thermal comfort period. Digestibility coefficients for dry matter, organic matter, neutral detergent fiber, and acid detergent fiber were higher in trial 2 than in trials 1 and 3. No statistical differences were found between trials 1 and 3 for these variables. Rumen passage rate was more rapid in trial 1 than in trials 2 and 3. No difference was observed between trials 2 and 3. These results indicated that exposure to a hot environment can affect digestibility in a time-dependent fashion, suggesting an adaptation of the digestive tract to hot environments.