Evaluation of feed restriction and abomasal infusion of resistant starch as models to induce intestinal barrier dysfunction in healthy lactating cows

ABSTRACT: Intestinal hyperpermeability and subsequent immune activation alters nutrient partitioning and thus, decreases productivity. Developing experimental models of intestinal barrier dysfunction in heathy cows is a prerequisite in identifying nutritional strategies to mitigate it. Six cannulated Holstein cows (mean ± standard deviation, 37 ± 10 kg/d milk yield; 219 ± 97 d in milk; 691 ± 70 kg body weight) were used in a replicated 3 × 3 Latin square design experiment with 21-d periods (16-d wash-out and 5-d challenge) to evaluate either feed restriction or hindgut acidosis as potential models for inducing intestinal hyperpermeability. Cows were randomly assigned to treatment sequence within square and treatment sequences were balanced for carryover effects. Treatments during the challenge were (1) control (CTR; ad libitum feeding); (2) feed restriction (FR; total mixed ration fed at 50% of ad libitum feed intake); and (3) resistant starch (RS; 500 g of resistant starch infused in abomasum once a day as a pulse-dose 30 min before morning feeding). The RS (ActiStar RT 75330, Cargill Inc.) was tapioca starch that was expected to be resistant to enzymatic digestion in the small intestine and highly fermentable in the hindgut. Blood samples were collected 4 h after feeding on d 13 and 14 of the wash-out periods (baseline data used as covariate), and on d 1, 3, and 5 of the challenge periods. Fecal samples were collected 4 and 8 h after the morning feeding on d 14 of the wash-out periods and d 5 of the challenge periods. By design, FR decreased dry matter intake (48%) relative to CTR and RS, and this resulted in marked reductions in milk and 3.5% FCM yields over time, with the most pronounced decrease occurring on d 5 of the challenge (34 and 27%, respectively). Further, FR increased somatic cell count by 115% on d 5 of the challenge relative to CTR and RS. Overall, FR increased nonesterified fatty acids (159 vs. 79 mEq/L) and decreased BHB (8.5 vs. 11.2 mg/dL), but did not change circulating glucose relative to CTR. However, RS had no effect on production or metabolism metrics. Resistant starch decreased fecal pH 8 h after the morning feeding (6.26 vs. 6.81) relative to CTR and FR. Further, RS increased circulating lipopolysaccharide binding protein (4.26 vs. 2.74 µg/mL) compared with FR only on d 1 of the challenge. Resistant starch also increased Hp (1.52 vs. 0.48 µg/mL) compared with CTR, but only on d 5 of the challenge. However, neither RS or FR affected concentrations of serum amyloid A, IL1β, or circulating endotoxin compared with CTR. The lack of consistent responses in inflammatory biomarkers suggests that FR and RS did not meaningfully affect intestinal barrier function. Thus, future research evaluating the effects of hindgut acidosis and FR using more intense insults and direct metrics of intestinal barrier function is warranted

Effects of a phytogenic feed additive on weaned dairy heifer calves subjected to a diurnal heat stress bout

ABSTRACT: The study objective was to evaluate the effects of a phytogenic feed additive (PFA) on dry matter intake (DMI), average daily gain (ADG), inflammation, and oxidative stress markers of heifer calves exposed to a heat stress bout in the summer. A total of18 Holstein and 4 Jersey heifer calves (192 ± 5 kg of body weight at 162 ± 16 d of age) housed in indoor stalls were assigned to 1 of 2 dietary treatments (n = 11; 9 Holstein and 2 Jersey): (1) a basal total mixed ration (CTL), and (2) CTL top-dressed with 0.25 g/d of PFA. Following 7 d of acclimation, baseline measurements were made over 7 d under regular summer conditions [average temperature-humidity index (THI) = 79 from 0900 to 2000 h, and 75 from 2000 to 0900 h]. Calves were then subjected to a 7-d cyclic heat stress bout (HS) by turning on barn heaters and increasing the barn temperature to 33.0°C only during the daytime (the average THI = 85 from 0900 to 2000 h). The study continued for an extra 4-d period after HS ended (post-HS). The HS increased rectal temperature, skin temperature, and respiration rate from the baseline by 1.0°C, 4.0°C, and 49 breaths/min, respectively. The drinking water intake increased by 32% in response to HS, and calves continued to consume more water (44%) than the baseline consumption even after HS ended. The treatment × time interactions were not significant for feed intake, ADG, partial pressure of O2 in the blood, and blood concentrations of inflammation markers such as haptoglobin and lipopolysaccharide binding protein (LBP), and antioxidant markers such as protein carbonyl and thiobarbituric acid (TBARS). The PFA tended to increase daytime DMI (0.24 kg/d) compared with CTL throughout the experiment but did not affect ADG, which decreased from 1.12 kg/d to 0.26 kg/d in response to HS. Both DMI (13%) and ADG (85%) increased during post-HS relative to baseline, indicating compensatory performances that were not affected by the PFA. Serum haptoglobin and plasma LBP concentrations of PFA calves were 44% and 38% lower than that of CTL calves across all time points. The PFA decreased O2 pressure and tended to decrease protein carbonyl concentration in the blood across all time points. The PFA tended to decrease TBARS concentration on the first day of HS and increase and decrease the ratio of reduced to oxidized glutathione in the blood during the baseline and post-HS periods, respectively. Despite the lack of growth improvements, feeding PFA seems to increase O2 levels in the blood and alleviate oxidative stress and inflammation of heifer calve exposed to diurnal heat waves (~7 d) in the summer

Effects of dietary antioxidant supplementation on metabolism and inflammatory biomarkers in heat-stressed dairy cows

ABSTRACT: Heat-stress-induced inflammation may be ameliorated by antioxidant supplementation due to the purported effects of increased production of reactive oxygen species or oxidative stress on the gastrointestinal tract barrier. Thus, study objectives were to evaluate whether antioxidant supplementation [AGRADO Plus 2.0 (AP); EW Nutrition] affects metabolism and inflammatory biomarkers in heat-stressed lactating dairy cows. Thirty-two mid-lactation multiparous Holstein cows were assigned to 1 of 4 dietary-environmental treatments: (1) thermoneutral (TN) conditions and fed a control diet (TN-CON; n = 8), (2) TN and fed a diet with AP (10 g antioxidant; n = 8), (3) heat stress (HS) and fed a control diet (HS-CON; n = 8), or (4) HS and fed a diet with AP (HS-AP; n = 8). The trial consisted of a 23-d prefeeding phase and 2 experimental periods (P). Respective dietary treatments were top-dressed starting on d 1 of the prefeeding period and continued daily throughout the duration of the experiment. During P1 (4 d), baseline data were collected. During P2 (7 d), HS was artificially induced using an electric heat blanket (Thermotex Therapy Systems Ltd.). During P2, the effects of treatment, day, and treatment-by-day interaction were assessed using PROC MIXED of SAS (SAS Institute Inc.). Heat stress (treatments 3 and 4) increased rectal, vaginal, and skin temperatures (1.2°C, 1.1°C, and 2.0°C, respectively) and respiration rate (33 breaths per minute) relative to TN cows. As expected, HS decreased dry matter intake, milk yield, and energy-corrected milk yield (32%, 28%, and 28% from d 4 to 7, respectively) relative to TN. There were no effects of AP on body temperature indices or production. Milk fat, protein, and lactose concentrations remained unaltered by HS or AP; however, milk urea nitrogen was increased during HS regardless of AP supplementation (26% relative to TN). Circulating glucose remained unchanged by HS, AP, or time. Additionally, HS decreased circulating glucagon (29% from d 3 to 7 relative to TN), but there was no additional effect of AP. There was a tendency for nonesterified fatty acid concentrations to be increased in HS-AP cows throughout P2 (60% relative to TN-CON), whereas it remained similar in all other treatments. Blood urea nitrogen increased for both HS treatments from d 1 to 3 before steadily decreasing from d 5 to 7, with the overall increase being most pronounced in HS-CON cows (27% relative to TN-CON). Further, supplementing AP decreased blood urea nitrogen in HS-AP on d 3 relative to HS-CON (15%). Circulating serum amyloid A tended to be and lipopolysaccharide binding protein was increased by HS, but neither acute-phase protein was affected by AP. Overall, AP supplementation appeared to marginally alter metabolism but did not meaningfully alter inflammation during HS

Effects of hindgut acidosis on metabolism, inflammation, and production in dairy cows consuming a standard lactation diet

ABSTRACT: Postruminal intestinal barrier dysfunction caused by excessive hindgut fermentation may be a source of peripheral inflammation in dairy cattle. Therefore, the study objectives were to evaluate the effects of isolated hindgut acidosis on metabolism, inflammation, and production in lactating dairy cows. Five rumen-cannulated lactating Holstein cows (32.6 ± 7.2 kg/d of milk yield, 242 ± 108 d in milk; 642 ± 99 kg of body weight; 1.8 ± 1.0 parity) were enrolled in a study with 2 experimental periods (P). During P1 (4 d), cows were fed ad libitum a standard lactating cow diet (26% starch dry matter) and baseline data were collected. During P2 (7 d), all cows were fed the same diet ad libitum and abomasally infused with 4 kg/d of pure corn starch (1 kg of corn starch + 1.25 L of H2O/infusion at 0600, 1200, 1800, and 0000 h). Effects of time (hour relative to the first infusion or day) relative to P1 were evaluated using PROC MIXED in SAS (version 9.4; SAS Institute Inc.). Infusing starch markedly reduced fecal pH (5.84 vs. 6.76) and increased fecal starch (2.2 to 9.6% of dry matter) relative to baseline. During P2, milk yield, milk components, energy-corrected milk yield, and voluntary dry matter intake remained unchanged. At 14 h, plasma insulin and β-hydroxybutyrate increased (2.4-fold and 53%, respectively), whereas circulating glucose concentrations remained unaltered. Furthermore, blood urea nitrogen increased at 2 h (23%) before promptly decreasing below baseline at 14 h (13%). Nonesterified fatty acids tended to decrease from 2 to 26 h (40%). Circulating white blood cells and neutrophils increased on d 4 (36 and 73%, respectively) and somatic cell count increased on d 5 (4.8-fold). However, circulating serum amyloid A and lipopolysaccharide-binding protein concentrations were unaffected by starch infusions. Despite minor changes in postabsorptive energetics and leukocyte dynamics, abomasal starch infusions and the subsequent hindgut acidosis had little or no meaningful effects on biomarkers of immune activation or production variables

Aeromonas species isolated from PINTADO fish (Pseudoplatystoma sp): virulence factors and drug susceptibility

Aeromonas has been described as an emergent foodborne pathogen of increasing importance. In this study, we report that 48% of 50 Pintado fish samples collected at the retail market of São Paulo city were positive for Aeromonas sp, as detected by the direct plating method. When the presence/absence method was used, the positivity was 42%. A. caviae was the most frequent species, followed by A. hydrophila and A. sobria. Production of cytotoxic enterotoxin, observed in suckling mouse assay, was detected in 67% of A. sobria strains, in 60% of A. hydrophila strains and in 40% of A. caviae strains. In vitro tests, performed with HEp-2 cells, showed that 88% of A. hydrophila, 27% of A. sobria and 13% of A. caviae strains were positive for this toxin. The in vivo production of cytotonic enterotoxin, tested after heating the filtrates at 56ºC for 20 minutes, was detected in 17% of A. sobria, in 10% of A. caviae and in none of A. hydrophila strains in vivo. All analyzed strains did not alter HEp-2 cells. 20% and 16% of A. sobria and A. caviae isolates, respectively, presented capacity to adhere to HEp-2 cells. In counterpart, invasion of HEp-2 cells was not observed in any isolate. The Aeromonas isolates were sensitive to the majority of the antimicrobiol agents tested.<br>Bactérias do gênero Aeromonas têm sido descritas como patógenos emergentes de importância crescente em alimentos. Neste estudo, relatamos que 48% das amostras de peixe "Pintado" coletado no comércio de São Paulo, foram positivas para Aeromonas sp quando isoladas pelo método de plaqueamento direto. Quando o método Presença/Ausência foi utilizado, a porcentagem de positividade foi de 42%. A. caviae foi a espécie mais freqüente, seguida por A. hydrophila e A. sobria. Produção de enterotoxina citotóxica, determinada em camundongos recém-nascidos, foi observada em 67% das cepas de A. sobria, em 60% das de A. hydrophila e em 40% das de A. caviae. No teste in vitro em células HEp- 88% das cepas de A. hydrophila, 27% das cepas de A. sobria e 13% das cepas de A. caviae revelaram-se positivas. Com relação a produção de enterotoxina citotônica, testada após o aquecimento do sobrenadante a 56ºC por 20 minutos, 17% das cepas de A. sobria, 10% das de A. caviae e nenhuma das de A. hydrophila foram positivas in vivo e para todas as cepas analisadas, os testes foram negativos em cultura de célula HEp-2. Quanto a capacidade de adesão, 20% das 5 cepas de A. sobria e 16% das 20 cepas de A. caviae aderiram a células HEp-2. A capacidade de invasão em células HEp-2 não foi detectada em nenhuma das cepas testadas. As cepas isoladas foram sensíveis a maior parte dos antimicrobianos testados