Summera Iqbal

Nutrition, microbiota, and endotoxin-related diseases in dairy cows

Neste artigo de revisao e apresentado um resumo total do papel que a dieta de alto teor de graos e baixo teor de forragem tem sobre a composicao da microbiota do rumen e como as mudancas na dieta afetam a liberacao de componentes da parede celular bacteriana toxicos ao hospedeiro. Um destes compostos toxicos e um lipopolisacarideo ou endotoxina, um componente da membrana exterior de todas bacterias gram-negativas. Tambem sao fornecidos dados que apoiam a ideia de que a endotoxina se transloca na circulacao sanguinea e que estas endotoxinas ruminais estao associadas a multiplas perturbacoes das variaveis sanguineas relacionadas a carboidratos, lipidios e metabolismo mineral. Alem disso, endotoxina induz resposta imune geral e nao especifica, denominada resposta aguda de fase. Destaca-se tambem o fato de que dietas de alto teor de grao estao associadas a grupos distintos de metabolitos do plasma e variaveis imunes, sugerindo que a mudanca na proporcao entre graos de cereal e forragem na dieta e muito importante para a saude do gado leiteiro. Fornecemos tambem informacoes que apoiam o conceito de que a endotoxina esta envolvida em multiplas doencas metabolicas, como figado gorduroso, febre do leite, laminitis, placenta retida, abomasum deslocado e sindrome downer cow. Maior numero de pesquisas e necessario para esclarecer os mecanismos pelo qual nutricao, microbiota e endotoxina contribuem para o desenvolvimento de doencas metabolicas. Concluimos que, alem dos agentes causais acima mencionados, outros compostos gerados na area de gastrointestinal, como acido de lipoteicoico ou aminas metiladas, podem estar envolvidos na etiologia de doencas metabolicas.

Feeding barley grain steeped in lactic acid modulates rumen fermentation patterns and increases milk fat content in dairy cows

The objectives of the present in vivo and in situ trials were to evaluate whether feeding barley grain steeped in lactic acid (LA) would affect rumen fermentation patterns, in situ dry matter (DM) degradation kinetics, and milk production and composition in lactating dairy cows. The in vivo trial involved 8 rumen-fistulated Holstein cows fed once daily a total mixed ration containing rolled barley grain (27% in DM) steeped for 48 h in an equal quantity of tap water (CTR) or in 0.5% LA (TRT) in a 2 x 2 crossover design. The in situ trials consisted of incubation of untreated rolled barley grain in cows fed CTR or TRT diets and of incubation of 3 different substrates including CTR or barley grain steeped in 0.5% or 1.0% LA (TRT1 and TRT2, respectively) up to 72 h in the rumen. Results of the in vivo trial indicated that cows fed the TRT diet had greater rumen pH during most intensive fermentation phases at 10 and 12 h post-feeding. The latter effect was associated with a shorter duration in which rumen pH was below 5.8 for cows fed the TRT diet (2.4 h) compared with CTR diet (3.9 h). Furthermore, cows fed the TRT diet had lower concentrations of volatile fatty acids at 2 and 4 h post-feeding. In addition, concentrations of preprandial volatile fatty acids were lower in the rumen fluid of cows fed the TRT diet. Results also showed that molar proportion of acetate was lower, whereas propionate tended to increase by feeding cows the TRT diet. Cows fed the TRT diet demonstrated greater rumen in situ lag time of substrate DM degradation and a tendency to lower the fractional degradation rate. Other in situ results indicated a quadratic effect of LA on the effective rumen degradability of substrates whereby the latter variable was decreased from CTR to TRT1 but increased for TRT2 substrate. Although the diet did not affect actual milk yield, fat-corrected milk, percentages of milk protein, and lactose and concentration of milk urea nitrogen, cows fed the TRT diet increased milk fat content and tended to increase fat:protein ratio in the milk. In conclusion, results demonstrated that treatment of barley grain with LA lowered the risk of subacute rumen acidosis and maintained high milk fat content in late-lactating Holstein cows fed diets based on barley grain.

Feeding rolled barley grain steeped in lactic acid modulated energy status and innate immunity in dairy cows

Feeding dairy cows large proportions of cereal grain is commonly associated with rumen acidosis, activation of innate immunity, and perturbation of intermediary metabolism. We previously showed that steeping barley grain in 0.5% lactic acid (LA) decreased the rate of starch degradation, lowered the risk of subacute rumen acidosis, modulated rumen fermentation profile, and increased milk fat content in dairy cows. This study sought to investigate whether feeding of LA-treated barley grain would affect carbohydrate and lipid metabolism as well as innate immunity. Eight rumen-fistulated late-lactation (approximately 217 d in milk, DIM) Holstein cows were randomly assigned, in a 2 × 2 crossover design, to 1 of the 2 dietary treatments consisting of 27% (dry matter basis) rolled barley grain steeped for 48 h in an equal volume (wt/vol) of tap water (CTR) or 0.5% LA (TRT). Each experimental period lasted 21 d, with the first 11 d for diet adaptation. Blood and rumen samples were collected on d 12, 15, 17, and 21 of the experimental period before the morning feeding to evaluate the effects of dietary treatment on preprandial day-to-day variation of plasma and rumen variables. To establish the effect of treatment on diurnal variation of plasma variables, blood samples were collected on the last day of each period at 0, 2, 4, 6, 8, 10, and 12h after the morning feeding (i.e., 0800 h). Results of the day-to-day study showed that cows fed the TRT diet had greater overall preprandial concentrations of glucose, cholesterol, and insulin, and a lower concentration of haptoglobin in plasma. Diurnal data indicated lower concentrations of haptoglobin and serum amyloid A and a tendency for greater plasma lactate in cows fed the TRT diet. A treatment by time interaction was observed for glucose, lactate, insulin, haptoglobin, and lipopolysaccharide-binding protein, suggesting a role for both the processing of grain and the time of sampling on those variables. No effect of diet on plasma concentrations of cortisol, β-hydroxybutyrate, and nonesterified fatty acids or rumen endotoxin was evidenced. Taken together, our results demonstrated that feeding barley grain steeped in 0.5% LA modulated both energy status and innate immunity of dairy cows fed relatively high levels (45% of dry matter) of dietary concentrate.

Barley grain-based diet treated with lactic acid and heat modulated plasma metabolites and acute phase response in dairy cows

This study investigated the effects of feeding barley grain treated with lactic acid (LA) and heat on the profile of plasma metabolites related to carbohydrate and lipid metabolism and variables related to rumen health and acute phase response. Eight primiparous rumen-fistulated lactating Holstein cows were randomly assigned, in a crossover design, to 1 of the 2 dietary treatments consisting of 32% (DM basis) rolled barley grain steeped in an equal quantity of either tap water alone (CTR) or a 1.0% LA solution and heated at 55°C for 48 h (LAH). Each experimental period was 21 d, with the last 10 d used for measurements. Blood samples were collected on d 1, 3, 5, 7, 9, and 11 before the morning feeding and on the last day of each period at 0, 2, 4, 6, 8, 10, and 12 h postfeeding to measure glucose, lactate, cholesterol, beta-hydroxybutyrate (BHBA), NEFA, haptoglobin (Hp), serum amyloid A (SAA), and tumor necrosis factor-alpha (TNF-α). Also, rumen samples were collected on d 1, 5, and 11 as well as at 0, 4, 8, and 12 h postfeeding on the last day of each period for measuring the concentration of rumen endotoxin. Results of the day-to-day analysis indicated that cows fed the LAH diet had reduced preprandial concentrations of rumen endotoxin (472 vs. 793 ng/mL; P < 0.01) and cholesterol and greater lactate in the plasma; however, treatment had no effect on plasma Hp and TNF-α (P > 0.10). Postprandial responses showed that the LAH diet tended to decrease the concentration of SAA (4.67 vs. 8.50 μg/mL; P = 0.06). Also, there was a treatment by time interaction for rumen endotoxin (P < 0.01), suggesting a role for both the treatment and the time of sampling on this variable. Furthermore, greater concentration of BHBA and a tendency for greater NEFA and reduced concentrations of plasma glucose were observed in cows fed the LAH diet. In conclusion, results indicated that feeding dairy cows barley grain steeped in 1.0% LA and treated with heat modulated the profile of plasma metabolites and acute phase response.

Application of Acute Phase Proteins for Monitoring Inflammatory States in Cattle

The animal body functions in a controlled internal environment, strictly regulated by a variety of homeostatic mechanisms. However, the internal milieu is disturbed by external factors that lead to imbalance of the inner homeostasis. The host is equipped with multiple tools to abolish external challenges like tissue injury and infection by activation of various defense mechanisms; however, mobilization of all these responses is associated with alterations of the homeostatic status. The multifaceted immune and metabolic responses of the host to external challenges are commonly referred to as the acute-phase response (APR) (Kushner, 1982; Koj, 1985; Baumann & Gauldie, 1994; Moshage, 1997; Mackiewicz, 1997). The aim of the APR is to eliminate the agent(s) that caused the interference and to bring the homeostasis back to normality (Figure 1). The APR is initiated in response to a variety of stimuli including acute trauma, bacterial infection, surgery, fracture, burns, tissue necrosis, presence of a chronic disease, or ongoing inflammatory processes (Kushner, 1982; Gordon & Koj, 1985; Baumann & Gauldie, 1994; Steel & Whitehead, 1994; Boosalis et al., 1996; Mackiewicz, 1997). The APR usually resolves within a few days or weeks, however sometimes it can persist when the causal agent is defiant (Boosalis et al., 1996; Mackiewicz, 1997; Koj, 1998). The APR is regulated by numerous compounds referred to as cytokines (Mackiewicz, 1997; Koj, 1998; Martin et al., 1999). The latter are produced by macrophages, when they are activated by bacterial endotoxin, viruses, free radicals, prostaglandins, or other factors released under different inflammatory conditions. The main cytokines released by macrophages are interleukin-1 (IL-1), IL-8, tumor necrosis factor-alpha (TNF-), and interferon-gamma (INF-) (Koj, 1998; Martin et al., 1999). The release of proinflammatory cytokines, at the site of tissue injury, stimulates various other cell types to produce a cascade of other cytokines, including IL-6-type cytokines, which act to stimulate the production of acute phase proteins (APP) from liver hepatocytes or other tissues (Baigrie et al., 1991; Mackiewicz, 1997). Although the production of cytokines in the liver or other local sites is complex, it is believed that IL-1 and IL-6 are the two main stimulants of APP production (Gauldie et al., 1987; Nijsten et al., 1991; Ohzato et al., 1992).

Intravaginal administration of lactic acid bacteria modulated the incidence of purulent vaginal discharges, plasma haptoglobin concentrations, and milk production in dairy cows

This investigation studied the effects of intravaginal administration of a mixture of lactic acid bacteria (LAB) on the incidence of purulent vaginal discharges (PVD), plasma haptoglobin concentrations, and milk production in dairy cows. A total of 82 pregnant primiparous and multiparous Holstein dairy cows were used in this study. Half of the cows received intravaginally 1mL of LAB at 10(10)-10(12)cfu/mL and the other half 1mL of reconstituted skim milk (i.e., carrier) (controls). Administration of LAB was conducted once per wk during 2 and 1wk before the expected day of calving and at 1, 2, 3, and 4wk postpartum. Data demonstrated that intravaginal administration of LAB decreased the occurrence of PVD at 3wk postpartum (P<0.05). Concentrations of plasma haptoglobin, an acute phase protein often associated with uterine infections, was lower in cows treated with the LAB mixture at 2wk (P<0.001) and 3wk (P<0.05) postpartum. Treatment with LAB did not improve overall pregnancy rate, but the treated multiparous cows produced more milk than their control counterparts (P<0.05), whereas no difference was observed in primiparous cows regarding milk yield (P>0.05). Overall, this is the first study demonstrating that intravaginal LAB administration lowers the incidence of PVD and enhances milk production in dairy cows. Further research is warranted to evaluate the effects of LAB on reproductive performance in a larger cohort of cows.

Oral administration of LPS and lipoteichoic acid prepartum modulated reactants of innate and humoral immunity in periparturient dairy cows

The study evaluated the effects of repeated oral exposure to LPS and lipoteichoic acid (LTA) on immune responses of dairy cows. Thirty pregnant Holstein cows were randomly assigned to two treatment groups. Cows received orally either 2 ml of 0.85% sterile saline solution (control group), or 2 ml of sterile saline solution containing three doses of LPS from Escherichia coli 0111 : B4 along with a flat dose of LTA from Bacillus subtilis. Blood and saliva samples were collected and analyzed for serum amyloid A (SAA); LPS-binding protein (LBP); anti-LPS plasma IgA, IgG and IgM; TNF-α; and IL-1. Results showed greater concentrations of IgA in the saliva of treated cows compared with the controls (P < 0.01). Treated cows had lower plasma concentrations of anti-LPS IgA, IgG and IgM Abs, and TNF-α than the controls (P < 0.05). There was a tendency for the concentrations of plasma LBP (P = 0.06) and haptoglobin (P = 0.10) to be lesser in the treatment group, although no differences were found in the concentration of plasma SAA and IL-1 (P > 0.10). Overall, the results of this study indicate that repeated oral administration with LPS and LTA stimulates innate and humoral immune responses in periparturient dairy cows.

Repeated oronasal exposure to lipopolysaccharide induced mucosal IgA responses in periparturient dairy cows.

This study investigated the effects of repeated oronasal treatment with lipopolysaccharide (LPS) on the humoral immune responses in saliva, vaginal mucus, and the plasma markers of the acute phase response in periparturient dairy cows. One hundred pregnant Holstein cows were administered either 3 increasing doses of LPS (n = 50) as follows: 1) 0.01 µg/kg body weight (BW) on d −28, 2) 0.05 µg/kg BW on d −25, and −21, and 3) 0.1 µg/kg BW on d −18, and −14, or sterile saline solution (controls; n = 50) oronasally for 3 consecutive wk starting at 28 d before parturition. Intensive sampling was conducted on thirty cows (n = 15/group). Multiple saliva, vaginal mucus and blood samples were collected around parturition and analyzed for total immunoglobulin-(Ig)A, plasma serum amyloid A (SAA), lipopolysaccharide-binding protein (LBP), anti-LPS IgA, IgG, IgM, tumour necrosis factor(TNF)-α, and interleukin(IL)-1. Results regarding total secretory IgA (sIgA) antibodies showed greater concentrations in the saliva and an overall tendency for higher total sIgA in the vaginal mucus of the LPS-treated cows. Treatment had no effect on plasma sIgA, IgG, IgM anti-LPS antibodies, haptoglobin, SAA, LBP, TNF-α, and IL-1. Treatments by time interactions were observed for SAA and IL-1 with lowered concentrations of both variables in the plasma of LPS-treated cows after parturition. Overall, repeated oronasal LPS treatment clearly enhanced total sIgA antibodies in the saliva, stimulated their production in vaginal mucus shortly before calving, and lowered plasma IL-1 around parturition, but showed limited effects on markers of the acute phase response in the plasma in dairy cows around parturition.