A decrease in insulin sensitivity enhances adipose tissue lipolysis helping early lactation cows counteracting their energy deficit. However, excessive lipolysis poses serious health risks for cows, and its underlying mechanisms are not clearly understood. The present study used targeted ESI-LC-MS/MS-based metabolomics and indirect insulin sensitivity measurements to evaluate metabolic alterations in the serum of dairy cows of various parities experiencing variable lipolysis early postpartum. Thirty (12 primiparous and 18 multiparous) cows of Holstein Friesian and Simmental breeds, fed the same diet and kept under the same management conditions, were sampled at d 21 postpartum and classified as low (n = 10), medium (n = 8), and high (n = 12) lipolysis groups, based on serum concentration of nonesterified fatty acids. Overall, excessive lipolysis in the high group came along with impaired estimated insulin sensitivity and characteristic shifts in acylcarnitine, sphingomyelin, phosphatidylcholine and lysophospholipid metabolome profiles compared to the low group. From the detected phosphatidylcholines mainly those with diacyl-residues showed differences among lipolysis groups. Furthermore, more than half of the detected sphingomyelins were increased in cows experiencing high lipomobilization. Additionally, strong differences in serum acylcarnitines were noticed among lipolysis groups. The study suggests an altered serum phospholipidome in dairy cows associated with an increase in certain long-chain sphingomyelins and the progression of disturbed insulin function. In conclusion, the present study revealed 37 key metabolites as part of alterations in the synthesis or breakdown of sphingolipids and phospholipids associated with lowered estimated insulin sensitivity and excessive lipolysis in early-lactating cows.

High-producing ruminants are fed high amounts of cereal grains, at the expense of dietary fiber, to meet their high energy demands. Grains consist mainly of starch, which is easily degraded in the rumen by microbial glycosidases, providing energy for rapid growth of rumen microbes and short-chain fatty acids (SCFA) as the main energy source for the host. Yet, low dietary fiber contents and the rapid accumulation of SCFA lead to rumen disorders in cattle. The chemical processing of grains has become increasingly important to confer their starch resistances against rumen microbial glycosidases, hence generating ruminally resistant starch (RRS). In ruminants, unlike monogastric species, the strategy of enhancing resistant starch is useful, not only in lowering the amount of carbohydrate substrates available for digestion in the upper gut sections, but also in enhancing the net hepatic glucose supply, which can be utilized by the host more efficiently than the hepatic gluconeogenesis of SCFA. The use of chemical methods to enhance the RRS of grains and the feeding of RRS face challenges in the practice; therefore, the present article attempts to summarize the most important achievements in the chemical processing methods used to generate RRS, and review advantages and challenges of feeding RRS to ruminants.

The present study aimed to investigate the long-term effect of feeding barley grain steeped in lactic acid (La) with or without thermal treatment on reticuloruminal pH dynamics and metabolic activity of the liver in 12 primiparous and 18 multiparous early-lactating dairy cows. All cows were included on d 21 postpartum and sampled until d 90 postpartum. Cows were fed a diet based on differently processed ground barley grain: untreated grain (control diet, CON), or grain treated with 1% La alone for 24 h before feeding (La), or with an additional oven-heating at 55°C for 12 h (LaH). The reticuloruminal pH and temperature were measured via indwelling sensors that allowed for continuous (every 10min) and long-term measurement from d 21 to 80 postpartum. Blood samples were taken on d 21, 40, and 90 of lactation and analyzed for liver enzymes aspartate aminotransferase (AST), gamma-glutamyltransferase, and glutamate dehydrogenase, as well as bilirubin, bile acids, and serum amyloid A. Dry matter intake was higher in multiparous cows (20.7±0.27 kg/d) compared with primiparous cows (18.2±0.33 kg/d), but was not affected by dietary treatment. Overall, the relatively short duration (51±5min/d) of reticuloruminal pH <5.8 suggests low risk of subacute ruminal acidosis throughout the experiment. Results indicated that La treatment of barley, with or without heat, lowered the time duration of pH <5.8 compared with CON, but only in primiparous cows (from 118±13 to 46±11 and 25±11min/d for CON, La, and LaH, respectively). In multiparous cows, the opposite effect of feeding the La-treated barley on time duration of pH <5.8 (11±8 vs. 46±9 vs. 57±9min/d for CON, La, and LaH, respectively) was observed. Multiparous cows generally showed higher pH readings and shorter periods in which the ruminal pH dropped below the threshold of pH 5.8. The reticuloruminal temperature was not affected by dietary treatment, whereas parity affected the time duration of reticuloruminal temperature >39.5°C, being 60±19min/d shorter in primiparous cows. The measured activities of the liver enzymes AST, gamma-glutamyltransferase, and glutamate dehydrogenase, as well as bilirubin, bile acids, and the acute phase protein serum amyloid A, were not affected by grain feeding. Additionally, only one small effect of parity on investigated serum variables was noticed, showing slightly but significantly higher values of AST in multiparous (80.5±1.4 U/L) compared with primiparous cows (76.0±1.7 U/L). In conclusion, our results indicate greater risk for primiparous cows to develop subacute ruminal acidosis-like conditions during early lactation than multiparous cows. The study also suggests limited benefits of feeding processed barley grain with La with or without thermal treatment to modulate ruminal tolerance of grain feeding, whereby differing effects in primiparous cows were observed compared with multiparous cows.

The aim of this study was to evaluate the accuracy and precision of indwelled wireless sensors relative to intrareticuloruminal differences in dairy cows transitioned from a forage to a high-concentrate diet. A feeding trial was performed with 8 rumen-cannulated Holstein cows. The cows were stepwise switched from 0 to 60% concentrate in the diet and fed 5 wk. Samples from the free ruminal liquid (FRL) from the ventral rumen and from the particle-associated ruminal liquid (PARL) in the rumen mat were manually taken at 0, 4, and 8 h after the morning feeding on d 0, 7, 14, and 34 of the experiment through the ruminal cannula to measure pH in FRL and PARL using a pH electrode. Additionally indwelling reticular wireless pH sensors were used to measure reticular pH every 10 min throughout the experiment. Precision and accuracy properties as a measure of reproducibility of the methods were statistically evaluated. Data showed significant differences among pH readings of indwelling sensors and pH measurements taken by means of a conventional electrode in both FRL and PARL (P<0.05). These differences became more evident when 60% concentrate diet was fed. Across all experimental days, the pH of the FRL was greatest and the pH reported by indwelling sensors intermediate, whereas the pH of PARL was lowest. The concordance correlation coefficient (CCC) analysis revealed a high agreement between indwelling sensors and FRL (CCC=0.709) but a low agreement with the pH of PARL (CCC=0.495). In conclusion, the study indicated that wireless sensors can satisfactorily reflect the pH of FRL but poorly reflect that of PARL.

Mastitis is not only a major cause of economic losses to the dairy industry but also a major problem in ensuring the quality and safety of the milk, associated with high somatic cell counts and residues of antibiotics used for treatment. One innovative approach to protection against mastitis is to stimulate the animal's natural defense mechanisms. Technological advances in immunological research have increased our ability to exploit the immunity of the bovine mammary gland during periods of high susceptibility to disease. The trace element selenium affects the innate and the adaptive immune responses of the mammary gland through cellular and humoral activities. Substantial research has been carried out on the effect of selenium (Se) on the immune function of the mammary gland and subsequent improvement in bovine udder health and mastitis control. Levels higher than current recommendations and Se-yeast can potentially be used to enhance our capacity to modulate the physiological mechanisms of the bovine mammary gland to respond to infection. This article provides an overview of the most recent research in this field.

Recent data indicate positive effects of treating grain with citric (CAc) or lactic acid (LAc) on the hydrolysis of phytate phosphorus (P) and fermentation products of the grain. This study used a semicontinuous rumen simulation technique to evaluate the effects of processing of barley with 50.25 g/L (wt/vol) CAc or 76.25 g/L LAc on microbial composition, metabolic fermentation profile, and nutrient degradation at low or high dietary P supply. The low P diet [3.1g of P per kg of dry matter (DM) of dietary P sources only] was not supplemented with inorganic P, whereas the high P diet was supplemented with 0.5 g of inorganic P per kg of DM through mineral premix and 870 mg of inorganic P/d per incubation fermenter via artificial saliva. Target microbes were determined using quantitative PCR. Data showed depression of total bacteria but not of total protozoa or short-chain fatty acid (SCFA) concentration with the low P diet. In addition, the low P diet lowered the relative abundance of Ruminococcus albus and decreased neutral detergent fiber (NDF) degradation and acetate proportion, but increased the abundance of several predominantly noncellulolytic bacterial species and anaerobic fungi. Treatment of grain with LAc increased the abundance of total bacteria in the low P diet only, and this effect was associated with a greater concentration of SCFA in the ruminal fluid. Interestingly, in the low P diet, CAc treatment of barley increased the most prevalent bacterial group, the genus Prevotella, in ruminal fluid and increased NDF degradation to the same extent as did inorganic P supplementation in the high P diet. Treatment with either CAc or LAc lowered the abundance of Megasphaera elsdenii but only in the low P diet. On the other hand, CAc treatment increased the proportion of acetate in the low P diet, whereas LAc treatment decreased this variable at both dietary P levels. The propionate proportion was significantly increased by LAc at both P levels, whereas butyrate increased only with the low P diet. Treatments with CAc or LAc reduced the degradation of CP and ammonia concentration compared with the control diet at both P levels. In conclusion, the beneficial effects of CAc and LAc treatment on specific ruminal microbes, fermentation profile, and fiber degradation in the low P diet suggest the potential for the treatment to compensate for the lack of inorganic P supplementation in vitro. Further research is warranted to determine the extent to which the treatment can alleviate the shortage of inorganic P supplementation under in vivo conditions.

This study investigated the effects of the probiotic Lactobacillus acidophilus strain DSM 13241 in dogs with non-specific dietary sensitivity (NSS). Six adult German Shorthair Pointers with NSS consecutively received a control dry diet and the same diet supplemented with the probiotic (6 x 10(6) cfu/g) for 12 weeks each, followed by another control period of four weeks. Frequency of defecations, faecal quality and nutrient digestibility were determined. Faeces were cultured for Clostridium perfringens, Escherichia spp., lactobacilli and bifidobacteria and quantitative fluorescence in situ hybridisation (FISH) was performed. Feeding the probiotic improved faecal consistency, faecal dry matter and defecation frequency (p < 0.05). Faecal concentrations of culturable lactobacilli and bifidobacteria increased numerically, but not significantly, also the decrease of the numbers of C. perfringens and Escherichia spp. did not reach the level of significance. Results from FISH showed more constant bacterial populations. It can be concluded that L. acidophilus DSM 13241 can stabilise the digestive processes in dogs with NSS.

The present study aimed to investigate changes in the reticuloruminal pH and temperature dynamics in periparturient dairy cows. Reticuloruminal pH and temperature measurements were conducted from 7 d before until 8 d after parturition using indwelling sensors. Nine Simmental and 4 Brown Swiss dairy cows were fed a close-up total mixed ration (52.5% neutral detergent fiber, 5.68MJ of net energy for lactation per kg of dry matter) with additional 1kg/cow per d concentrate mixture (29.5% neutral detergent fiber and 6.25MJ of net energy for lactation per kg of dry matter), starting from 2 wk before the estimated calving date. Postpartum, all cows had free access to the same close-up diet and were gradually fed increasing amounts of a concentrate-rich total mixed ration for early-lactation cows (32.7% neutral detergent fiber, 7.22MJ of net energy for lactation per kg of dry matter). Data showed depressed reticuloruminal pH early postpartum, but only in the group of cows defined as subacute ruminal acidosis (SARA) susceptible (n=8), which had a higher duration time of pH <5.8 (753±82min/d) compared with SARA-tolerant cows (n=5; 15±6min/d). Also, compared with SARA-tolerant cows (112±91min/d), the SARA-susceptible group showed longer (1,049±75min/d) duration time of pH <6.0. When compared by breed, mean reticuloruminal pH tended to be lower in Simmental (6.16±0.03) than in Brown Swiss cows (6.25±0.05), but no differences were observed in the duration of pH <5.8 between breeds. Simmental cows produced more milk (30.4±1.2kg/d) compared with Brown Swiss cows (27.9±1.3kg/d). Neither total dry matter intake nor milk yield were different between SARA-susceptible and SARA-tolerant groups. However, SARA-tolerant cows consumed greater amounts of the close-up total mixed ration than their SARA-susceptible counterparts, whereas no difference was observed in the intake of the early-lactating total mixed ration between the groups. Reticuloruminal temperature was not affected by breed or SARA susceptibility. Interestingly, the mean reticuloruminal temperature and the time duration of temperature >39.5°C abruptly dropped from d 2 to 1 before calving by 0.35°C and 430min/d, respectively. In conclusion, the strong inter-animal variation in reticuloruminal pH responses suggests the need for more careful monitoring and differentiated feeding management of cows during the transition period, whereby the SARA-susceptible cows may require particular attention regarding feeding management and diet composition. The abrupt decrease in reticuloruminal temperature the day before parturition may enable this noninvasive method as a management tool for prediction of parturition time.