Symposium review: Fiber and in vitro methods, analytical variation, and contributions to feed analysis.

At least 2 basic inputs are needed to formulate rations: the nutritional requirements of the animals to be fed and the nutritional composition of the feeds. David R. Mertens not only defined fiber requirements for dairy cattle but became a leading expert in the laboratory measurement of fiber in feeds, digesta, and feces. Fiber is a heterogeneous nutritional entity composed mainly of polysaccharides and polyphenolics. Because the method defines the fiber that is measured, methods must be described thoroughly and followed exactly to obtain results that are repeatable within a laboratory and reproducible among others. Filtration of neutral detergent fiber (NDF) can be difficult, and those who have worked in his laboratory can attest that Mertens rigorously studied this, along with other method details to improve NDF analysis from sample preparation to blank corrections. Mertens's procedure for amylase-treated NDF (aNDF), using α-amylase and sodium sulfite with crucibles, culminated in the Association of Official Analytical Chemists Official Method 2002.04 for aNDF, which was also accepted as International Standard ISO 16472:2006 and is used worldwide as a reference method for feed evaluation. Because aNDF digestibility is variable and a key factor in overall digestibility, Mertens also worked to improve in vitro ruminal digestibility and gas production procedures within and among laboratories, including procedures using flasks or filter bags. His in vitro gas production method is currently used by commercial laboratories that generate a significant share of the aNDF digestibility results reported worldwide. Outside of the laboratory, his extensive outreach to commercial and research laboratories has had a huge impact on fiber analysis, in vitro digestibility, and other laboratory procedures. While advising the National Forage Testing Association, Mertens provided program infrastructure that improved laboratory proficiency in more than 120 laboratories in the United States and around the world. Most importantly, thanks to his advances in fiber analysis and in vitro digestibility techniques, Mertens has enhanced the evaluation of feeds and the nutrition and health of dairy cows. These contributions have helped thousands of dairy farmers and nutritionists around the globe and continue to have a substantial impact on the industry.

Evaluating the inclusion of alfalfa hay in diets fed to multigravid Holstein cows in their transition to early lactation.

The objectives of this study were to determine the dry matter intake (DMI), urine pH, Ca concentration in blood, Ca output in urine, and frequency of hypocalcemia in pregnant and nonlactating dairy cows consuming diets containing different hays and acidogenic products during the prepartum period. Eighty pregnant and nonlactating Holstein cows approaching their second or greater calving were fed 1 of 4 experimental diets according to a 2 × 2 factorial arrangement of treatments during the prepartum period (21 d before calving). Diets included either grass hay (GH) or alfalfa hay (AH) and calcium chloride (CL) or polyhalite (PO) as the acidogenic products. All diets had a dietary cation-anion difference (DCAD) below -190 mEq/kg of dry matter (DM). Grass hay contained 75 g/kg crude protein, 749 g/kg neutral detergent fiber, 3.6 g/kg Ca, 0.9 g/kg Na, 18.8 g/kg K, 3.8 g/kg Cl, 1.5 g/kg S, and a cation-anion difference equal to 290 mEq/kg of DM. Alfalfa hay contained 196 g/kg crude protein, 456 g/kg neutral detergent fiber, 15.2 g/kg Ca, 1.6 g/kg Na, 25 g/kg K, 7.7 g/kg Cl, 3.2 g/kg S, and a cation-anion difference equal to 292 mEq/kg of DM. Cows consuming GH tended to consume more DM than cows consuming AH (11.6 vs. 10.8 kg/d) but DMI did not differ between acidogenic products. Urine pH decreased below 6.5 for all diets, although cows consuming the GHPO diet had the highest urine pH. The concentration of Ca in plasma decreased substantially around calving but neither hay type nor acidogenic product affected it. Urinary Ca output was lowest for cows consuming the GHPO diet. No associations existed between dietary treatments and the frequencies of normocalcemia and hypocalcemia. Under the conditions of this study, in which alfalfa and grass hays had similar cation-anion differences, we concluded that the inclusion of alfalfa hay in prepartum diets does not necessarily increase the frequency of hypocalcemia. The cation-anion difference of the alfalfa hay, more than the concentration of potassium alone, may be a key determinant of whether alfalfa hay fits in a prepartum feeding program for prepartum dairy cows. Further research should explore this relationship.

N-methyl-D-aspartate receptor-mediated calcium influx connects amyloid-ß oligomers to ectopic neuronal cell cycle reentry in Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) symptoms reflect synaptic dysfunction and neuron death. Amyloid-ß oligomers (AßOs) induce excess calcium entry into neurons via N-methyl-D-aspartate receptors (NMDARs), contributing to synaptic dysfunction. The study described here tested the hypothesis that AßO-stimulated calcium entry also drives neuronal cell cycle reentry (CCR), a prelude to neuron death in AD. METHODS: Pharmacologic modulators of calcium entry and gene expression knockdown were used in cultured neurons and AD model mice. RESULTS: In cultured neurons, AßO-stimulated CCR was blocked by NMDAR antagonists, total calcium chelation with 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), or knockdown of the NMDAR subunit, NR1. NMDAR antagonists also blocked the activation of calcium-calmodulin-dependent protein kinase II and treatment of Tg2576 AD model mice with the NMDAR antagonist, memantine, prevented CCR. DISCUSSION: This study demonstrates a role for AßO-stimulated calcium influx via NMDAR and CCR in AD and suggests the use of memantine as a disease-modifying therapy for presymptomatic AD.

Effect of biotin and pantothenic acid on performance and concentrations of avidin-binding substances in blood and milk of lactating dairy cows.

We hypothesized that pantothenic acid reduces the absorption of biotin in lactating dairy cows. Therefore, the objective of this study was to evaluate the plausible interaction between biotin and pantothenic acid on production performance and concentration of avidin-binding substances (ABS), an indicator of biotin concentration, in blood and milk of lactating dairy cows. Eight primiparous and 16 multiparous Holstein cows were assigned to 1 of 4 diet sequences in a replicated 4×4 Latin square design with 18-d periods. Cows were housed in a freestall barn and fed once daily (0730 h) by means of a Calan gate system (American Calan Inc., Northwood, NH). Treatments consisted of a control diet that contained no B-vitamins, a biotin diet that contained 0.87 mg of biotin per kilogram of dry matter (DM), a pantothenic acid diet that contained 21 mg of pantothenic acid per kilogram of DM, and a biotin plus pantothenic acid diet that contained 0.87 mg of biotin and 21 mg of calcium pantothenic acid per kilogram of DM. Four different concentrates were prepared in a commercial feed mill. These concentrates were mixed with corn silage and grass hay and delivered ad libitum as a total mixed ration. Biotin supplementation did not affect DM intake, milk yield, or milk fat, protein, lactose, and milk-urea-nitrogen concentrations. Fat, protein, and lactose yields were not affected by treatments. The fat-to-protein ratio was <1 and similar among all treatments. Biotin supplementation did not increase the concentration of ABS in plasma. The supplementation of pantothenic acid did not affect the concentration of ABS in plasma when either supplemented alone or in combination with biotin. Biotin supplementation increased the concentration of ABS in milk relative to control. Contrary to our hypothesis, the supplementation of pantothenic acid did not decrease the concentration of ABS in milk relative to the control. When cows were supplemented with both biotin and pantothenic acid, the concentration of ABS in milk was similar to that of cows supplemented with biotin alone. In conclusion, pantothenic acid did not affect the concentrations of ABS in plasma and milk, suggesting that increasing dietary supply of pantothenic acid did not inhibit biotin absorption.

Gating of thermally activated channels.

A class of ion channels that belongs to the transient receptor potential (TRP) superfamily and is present in specialized neurons that project to the skin has evolved as temperature detectors. These channels are classified into subfamilies, namely canonical (TRPC), melastatin (TRPM), ankyrin (TRPA), and vanilloid (TRPV). Some of these channels are activated by heat (TRPM2/4/5, TRPV1-4), while others by cold (TRPA1, TRPC5, and TRPM8). The general structure of these channels is closely related to that of the voltage-dependent K(+) channels, with their subunits containing six transmembrane segments that form tetramers. Thermal TRP channels are polymodal receptors. That is, they can be activated by temperature, voltage, pH, lipids, and agonists. The high temperature sensitivity in these thermal TRP channels is due to a large enthalpy change (∼100 kcal/mol), which is about five times the enthalpy change in voltage-dependent gating. The characterization of the macroscopic currents and single-channel analysis demonstrated that gating by temperature is complex and best described by branched or allosteric models containing several closed and open states. The identification of molecular determinants of temperature sensitivity in TRPV1, TRPA1, and TRPV3 strongly suggest that thermal sensitivity arises from a specific protein domain.

Effect of planting density on nutritional quality of green-chopped corn for silage.

The objective of this on-farm study was to determine the effect of corn planting density on the nutritional quality of whole-plant corn for silage. This study was performed in a commercial 1,900-cow dairy farm located in Piedritas (Buenos Aires, Argentina). Two commercial hybrids (A and B) were planted in experimental plots within a cornfield destined for corn silage. Hybrids were sown at a theoretical seeding rate of 60,000, 70,000, 80,000, and 90,000 seeds/ha in 4 replicates per hybrid. Plots were eight 50-m-long rows separated by 52cm. Corn was planted with a no-till seeder equipped with a pneumatic dosing machine. Ten plants within each plot were cut by hand at 15cm above ground. Whole plants were chopped, weighed, mixed thoroughly, and frozen until analysis. Nutritional composition was determined by near-infrared reflectance spectroscopy. Harvesting occurred at one-quarter milk-line [31.4% dry matter (DM)] and one-half milk-line (34.5% DM) stages of maturity for hybrids B and A, respectively. No interactions between hybrid and planting density were observed for any of the variables of interest. Planting density did not affect either plant DM weight or DM, crude protein, neutral detergent fiber, acid detergent fiber, or starch concentrations of whole-plant corn. Dry matter yield was significantly increased at higher planting densities. The similar per-plant biomass and nutritional quality among different densities can be explained by the abundant precipitation observed during this growing season (719mm since the beginning of fallow until harvest). In conclusion, greater yields of silage can be obtained by increasing corn planting density without affecting its nutritional composition, although the effect of planting density with limiting resources (e.g., precipitation) still needs to be elucidated.

Reproductive performance of dairy farms in western Buenos Aires province, Argentina.

The objective of this study was to describe the reproductive performance of 23 grazing-based dairy farms from western Buenos Aires province in Argentina. The data set included data from the breeding season starting in May 2011 and ending in March 2012. Submission, conception, and pregnancy rates ranged from 42.4 to 70.2%, 20.1 to 44.9%, and 10.3 to 24.5%, respectively. No correlation was observed between conception and submission rates, suggesting that dairy farms with poor submission rates but with relatively high conception rates might increase pregnancy rates by simply putting more effort into increasing estrus detection and submission rates. Decreases in submission and conception rates were observed among 21-d cycles, indicating seasonal variation. A greater number of cows in estrus at the beginning of the breeding period could have facilitated estrus detection and therefore increased submission rates. In addition, restarting the breeding activities with timed artificial insemination programs may explain the highest submission rates at the beginning of the breeding period. A first decrease of 5.1 percentage units in conception rate was observed during the spring (October-November) and an additional decrease of 2.4 percentage units in conception rate was observed during the summer (January-February). Decreases in conception rates could be related to high intakes of high-protein diets, heat stress, or a combination of both. Attenuating heat stress during the summer may be critical for maximizing conception rates in grazing systems from western Buenos Aires province.

Nutritional Composition and In Vitro Ruminal Digestibility of Crabgrass (Digitaria sanguinalis (L.) Scop.) in Monoculture or Interseeded with Cowpea (Vigna unguiculata (L.) Walp) and Lablab (Lablab purpureus (L.) Sweet).

The objective of this study was to evaluate the effects of interseeding crabgrass (CG) with two annual summer legumes on forage nutritional composition, dry matter (DM) yield, and in vitro fiber digestibility. The study was conducted as a randomized complete block design with four replicates per treatment. Plots were randomly assigned to one of six forage mix treatments. Crabgrass, cowpea (CWP), and lablab (LL) were planted in monoculture or in mixtures, resulting in six treatments. Throughout the growing season (three cuts), CG had the highest biomass yield, followed by the CG grown in mixtures with CWP and LL, whereas the two annual legume monocultures had the lowest yield. Cowpea and LL planted in monocultures had the highest concentration of CP and fiber digestibility, while the CG monoculture had the lowest. Furthermore, growing CG in a mixture with CWP and LL boosted the CP concentration and fiber digestibility to intermediate levels to those observed between both legume monocultures and CG. Regardless of treatment, the highest forage quality and yield was observed in the first harvest, with a drastic decline in the following harvests. In conclusion, the benefits of mixing crabgrass with legumes might be less than expected and should be carefully evaluated by livestock producers, especially when considering the effects of DM yield, forage quality, and pasture seeding costs.

Long-term in situ ruminal degradation of biodegradable polymers in Holstein dairy cattle.

Using biodegradable materials such as polyhydroxyalkanoates (PHA) and poly(butylene succinate-co-adipate) (PBSA) to develop single-use agricultural plastics like bale netting may reduce the negative effects of plastic accumulation in the rumens of cattle. The objective of this research was to assess the long-term degradation of PHA, PBSA, and a PBSA:PHA blend (Blend) compared with a low-density polyethylene (LDPE) control. Polyhydroxyalkanoate, PBSA, Blend, and LDPE films were incubated in the rumens of 3 cannulated, nonlactating Holsteins for up to 150 d. In situ disappearance (ISD) and residue length were assessed after every incubation time. Data were analyzed with PROC MIXED in SAS and adjusted by Tukey's method to determine least squares differences between polymer treatments, incubation time, and their interaction. By 30 d, PHA achieved 100% degradation, with initiation occurring at 14 d indicated by ISD and a reduction in residue length. Poly(butylene succinate-co-adipate) and Blend did not achieve any significant ISD, but fragmentation of PBSA occurred at 60 d and fragmentation of Blend at just 1 d, likely due to abiotic hydrolysis. Low-density polyethylene achieved no ISD, and residue length did not change over incubation time. We propose that a PBSA:PHA blend is a valid alternative to polyethylene single-use agricultural plastic products based on its fragmentation within 1 d of incubation.

Effect of drought stress on neutral detergent fiber degradation kinetics of corn for silage.

The objective of this study was to determine the effect of irrigation on in situ neutral detergent fiber (NDF) degradability of corn tissues from plants grown under controlled conditions in a greenhouse. Five commercial corn hybrids were planted in 6 pots that were placed in a greenhouse. Pots were randomly subjected to 2 irrigation regimens, which consisted of either abundant (A; 598 mm) or restricted (R; 273 mm) irrigation. At harvesting, leaf blades and stem internodes were collected from the upper and bottom portion of the plants. Tissue samples were incubated in the rumen of 3 rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 h to determine in situ NDF degradation kinetics. Drought stress did not affect the concentration of undegraded NDF (uNDF) in upper or bottom internodes but slightly decreased it in upper leaf blades (17.5 and 15.7% for A and R, respectively). The concentration of uNDF differed substantially among corn hybrids in upper internodes (13.4 to 28.3% uNDF), bottom internodes (21.5 to 42.3% uNDF), and upper leaf blades (11.6 to 20.1% uNDF). No interactions existed between irrigation treatment and corn hybrid for uNDF concentration. Drought stress did not affect the fractional degradation rate (kd) of NDF in upper internodes, bottom internodes, or upper leaf blades. The kd of NDF differed among corn hybrids in upper (3.8 to 6.6%/h) and bottom internodes (4.2 to 6.7%/h) but did not vary in upper leaf blades (3.8%/h). No interactions existed between irrigation treatment and corn hybrids for the kd of NDF. Significant interactions existed between irrigation treatment and corn hybrids for the effective ruminal degradation (ERD) of NDF in upper and bottom internodes. This interaction did not exist for upper leaf blades. The ERD of NDF differed substantially among corn hybrids in upper leaf blades (32.5 to 39.1%). In conclusion, drought-stressed corn had a marginal increase of NDF degradability of leaf blades but not in stem internodes, and drought stress had no effects on ERD of NDF. The effect of drought stress on NDF degradability of corn for silage is still inconclusive and deserves further investigation.

Yield, Nutritional Composition, and Digestibility of Conventional and Brown Midrib (BMR) Pearl Millet as Affected by Planting and Harvesting Dates and Interseeded Cowpea.

The objective of this study was to evaluate the yield, nutritional composition, and digestibility of conventional (CON) and brown midrib (BMR) pearl millet (PM) with different establishment dates, maturity at harvest and when mixed with cowpea (CWP). In trial 1, CON and BMR were planted on two different dates. In trial 2, CON and BMR, mixed or not with CWP, were harvested when PM was at the boot or heading stages. In trial 1, dry matter (DM) yield was similar between both PM genotypes but delaying establishment reduced DM yield by 30%. Additionally, BMR had a lower concentration of acid detergent lignin (ADL) and a higher in vitro neutral detergent fiber digestibility (IVNDFD) compared to CON. In Trial 2, the DM yield was 7.3% higher for CON compared to BMR, and PM with the BMR trait had a lower level of ADL and higher IVNDFD compared to CON. Mixing PM with CWP had negligible effects on nutritional composition but reduced DM yield by 8.3%. Results of these studies indicated that fiber from BMR PM is more digestible than CON but, in one of the trials, this occurred at the expense of lower DM yield. Mixing CWP with PM negatively impacted DM yield.

Clearance of Biodegradable Polymer and Polyethylene Films from the Rumens of Holstein Bull Calves.

Due to the occurrence of plastic impaction in ruminants and its deleterious effects on health and production, it is necessary to determine the suitability of biodegradable polymers to replace polyethylene-based agricultural plastics, such as hay netting. The objectives of this study were to evaluate the clearance of a polyhydroxyalkanoate (PHA) and poly(butylene succinate-co-adipate) (PBSA) melt-blend polymer from the rumen when fed to cattle and subsequent animal health. Twelve Holstein bull calves were dosed with an encapsulated 13.6 g of PBSA:PHA (Blend), 13.6 g of low-density polyethylene (LDPE), or four empty gelatin capsules (Control) for 30 d. The feed intake, body weight, and body temperature were evaluated, and hemograms were run on d 0 and d 30. On d 31, calves were euthanized to evaluate gross rumen measurements and pathology, papillae length, and polymer residues in rumen contents. No calves presented any signs related to plastic impaction. The feed intake; body weight; rectal temperature; hematological parameters; gross rumen measurements and pathology; and rumen pH and temperature were not affected by treatments. Calves dosed with LDPE had 27 g of undegraded polymer retained in the rumen while Blend calves had only 2 g of fragmented polymers that were 10% of their original size. Agricultural plastics developed from PBSA:PHA may be a suitable alternative to LDPE-based products in the case of animal ingestion and may reduce the incidence of plastic impaction.

Nutrigenomics of inward rectifier potassium channels.

Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg2+. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.

Bacterial toxins and heart function: heat-labile Escherichia coli enterotoxin B promotes changes in cardiac function with possible relevance for sudden cardiac death.

Bacterial toxins can cause cardiomyopathy, though it is not its most common cause. Some bacterial toxins can form pores in the membrane of cardiomyocytes, while others can bind to membrane receptors. Enterotoxigenic E. coli can secrete enterotoxins, including heat-resistant (ST) or labile (LT) enterotoxins. LT is an AB5-type toxin that can bind to specific cell receptors and disrupt essential host functions, causing several common conditions, such as certain diarrhea. The pentameric B subunit of LT, without A subunit (LTB), binds specifically to certain plasma membrane ganglioside receptors, found in lipid rafts of cardiomyocytes. Isolated guinea pig hearts and cardiomyocytes were exposed to different concentrations of purified LTB. In isolated hearts, mechanical and electrical alternans and an increment of heart rate variability, with an IC50 of ~0.2 µg/ml LTB, were observed. In isolated cardiomyocytes, LTB promoted significant decreases in the amplitude and the duration of action potentials. Na+ currents were inhibited whereas L-type Ca2+ currents were augmented at their peak and their fast inactivation was promoted. Delayed rectifier K+ currents decreased. Measurements of basal Ca2+ or Ca2+ release events in cells exposed to LTB suggest that LTB impairs Ca2+ homeostasis. Impaired calcium homeostasis is linked to sudden cardiac death. The results are consistent with the recent view that the B subunit is not merely a carrier of the A subunit, having a role explaining sudden cardiac death in children (SIDS) infected with enterotoxigenic E. coli, explaining several epidemiological findings that establish a strong relationship between SIDS and ETEC E. coli. Supplementary Information: The online version contains supplementary material available at 10.1007/s12551-023-01100-6.

Human spermatozoa possess a calcium-dependent chloride channel that may participate in the acrosomal reaction.

Motility, maturation and the acrosome reaction (AR) are fundamental functions of mammalian spermatozoa. While travelling through the female reproductive tract, spermatozoa must mature through a process named capacitation, so that they can reach the egg and undergo the AR, an exocytotic event necessary to fertilize the egg. Though Cl⁻ is important for sperm capacitation and for the AR, not much is known about the molecular identity of the Cl⁻ transporters involved in these processes.We implemented a modified perforated patch-clamp strategy to obtain whole cell recordings sealing on the head of mature human spermatozoa.Our whole cell recordings revealed the presence of a Ca²âº-dependent Cl⁻ current. The biophysical characteristics of this current and its sensitivity to niflumic acid (NFA) and 4,4-diisothiocyano-2,2-stilbene disulphonic acid (DIDIS) are consistent with those displayed by the Ca²âº-dependent Cl⁻ channel from the anoctamin family (TMEM16). Whole cell patch clamp recordings in the cytoplasmic droplet of human spermatozoa corroborated the presence of these currents, which were sensitive to NFA and to a small molecule TMEM16A inhibitor (TMEM16Ainh, an aminophenylthiazole). Importantly, the human sperm AR induced by a recombinant human glycoprotein from the zona pellucida, rhZP3, displayed a similar sensitivity to NFA, DIDS and TMEM16Ainh as the sperm Ca²âº-dependent Cl⁻ currents. Our findings indicate the presence of Ca²âº-dependent Cl⁻ currents in human spermatozoa, that TMEM16A may contribute to these currents and also that sperm Ca²âº-dependent Cl⁻ currents may participate in the rhZP3-induced AR.

Digestibility Kinetics of Polyhydroxyalkanoate and Poly(butylene succinate-co-adipate) after In Vitro Fermentation in Rumen Fluid.

Using polyhydroxyalkanoate (PHA) materials for ruminal boluses could allow for longer sustained release of drugs and hormones that would reduce administration time and unneeded animal discomfort caused by continuous administration. The objective of this study was to determine ruminal degradability and kinetics of biodegradable polymers and blends. A proprietary PHA-based polymer, poly(butylene succinate-co-adipate) (PBSA), PBSA:PHA melt blends, and forage controls were incubated in rumen fluid for up to 240 h. Mass loss was measured after each incubation time, and digestion kinetic parameters were estimated. Thermogravimetric, differential scanning calorimetry, and intrinsic viscosity analyses were conducted on incubated samples. Generally, across treatments, mass loss was significant by 96 h with a minimum increase of 0.25% compared to 0 h but did not change thereafter. Degradation kinetics demonstrated that polymer treatments were still in the exponential degradation phase at 240 h with a maximum disappearance rate of 0.0031 %/h. Melting temperature increased, onset thermal degradation temperature decreased, and intrinsic viscosity decreased with incubation time, indicating structural changes to the polymers. Based on these preliminary findings, the first stage of degradation occurs within 24 h and PHA degrades slowly. However, further ruminal degradation studies of biodegradable polymers are warranted to elucidate maximum degradation and its characteristics.

Functional consequences of lead and mercury exposomes in the heart.

Lead and mercury are heavy metals that are highly toxic to life forms. There are no known physiological processes that require them, and they do not have a particular threshold concentration to produce biologic damage. They are non-biodegradable, and they slowly accumulate in the environment in a dynamic equilibrium between air, water, soil, food, and living organisms. Their accumulation in the environment has been increasing over time, because they were not banned from use in anthropogenic industrial production. In their +2 cationic state they are powerful oxidizing agents with the ability to interfere significantly with processes that require specific divalent cations. Acute or chronic exposure to lead and mercury can produce multisystemic damage, especially in the developing nervous systems of children and fetuses, resulting in variety of neurological consequences. They can also affect the cardiovascular system and especially the heart, either directly through their action on cardiomyocytes or indirectly through their effects on innervation, humoral responses or blood vessel alterations. For example, heart function modified by these heavy metals are heart rate, contraction, excitability, and rhythm. Some cardiac molecular targets have been identified and characterized. The direct mechanisms of damage of these heavy metals on heart function are discussed. We conclude that exposome to these heavy metals, should be considered as a major relevant risk factor for cardiac diseases.

Pathophysiological and molecular considerations of viral and bacterial infections during maternal-fetal and -neonatal interactions of SARS-CoV-2, Zika, and Mycoplasma infectious diseases.

During pregnancy, a series of physiological changes are determined at the molecular, cellular and macroscopic level that make the mother and fetus more susceptible to certain viral and bacterial infections, especially the infections in this and the companion review. Particular situations increase susceptibility to infection in neonates. The enhanced susceptibility to certain infections increases the risk of developing particular diseases that can progress to become morbidly severe. For example, during the current pandemic caused by the SARS-CoV-2 virus, epidemiological studies have established that pregnant women with COVID-19 disease are more likely to be hospitalized. However, the risk for intensive care unit admission and mechanical ventilation is not increased compared with nonpregnant women. Although much remains unknown with this particular infection, the elevated risk of progression during pregnancy towards more severe manifestations of COVID-19 disease is not associated with an increased risk of death. In addition, the epidemiological data available in neonates suggest that their risk of acquiring COVID-19 is low compared with infants (<12 months of age). However, they might be at higher risk for progression to severe COVID-19 disease compared with older children. The data on clinical presentation and disease severity among neonates are limited and based on case reports and small case series. It is well documented the importance of the Zika virus infection as the main cause of several congenital anomalies and birth defects such as microcephaly, and also adverse pregnancy outcomes. Mycoplasma infections also increase adverse pregnancy outcomes. This review will focus on the molecular, pathophysiological and biophysical characteristics of the mother/placental-fetal/neonatal interactions and the possible mechanisms of these pathogens (SARS-CoV-2, ZIKV, and Mycoplasmas) for promoting disease at this level.

Ruminal Fiber Degradation Kinetics within and among Warm-Season Annual Grasses as Affected by the Brown Midrib Mutation.

The objective of this study was to compare the nutritional composition and the neutral detergent fiber (NDF) degradation kinetics of brown midrib (BMR) and non-BMR genotypes within and across warm-season annual grasses. Four commercial varieties (two non-BMR and two BMR) of corn, sorghum, and pearl millet were planted in plots. Forage samples were incubated in the rumen of three rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 h. On an NDF basis, all forage types showed lower acid detergent lignin (ADL) concentrations for BMR genotypes, but the magnitude of the difference differed among forage types. The concentration of undegraded NDF (uNDF; NDF basis) differed among forage types and between genotypes. Corn had the least, pearl millet had the intermediate, and sorghum had the greatest concentration of uNDF. Non-BMR genotypes had greater concentrations of uNDF than BMR genotypes. No interaction existed between forage type and genotype for the concentration of uNDF. In conclusion, although BMR forages may show lower ADL concentrations in the cell wall and greater NDF degradability than non-BMR forages of the same forage type, BMR forages do not always have the least ADL concentration or the greatest NDF degradability when comparing different forage types.

SARS-CoV-2, Zika viruses and mycoplasma: Structure, pathogenesis and some treatment options in these emerging viral and bacterial infectious diseases.

The molecular evolution of life on earth along with changing environmental, conditions has rendered mankind susceptible to endemic and pandemic emerging infectious diseases. The effects of certain systemic viral and bacterial infections on morbidity and mortality are considered as examples of recent emerging infections. Here we will focus on three examples of infections that are important in pregnancy and early childhood: SARS-CoV-2 virus, Zika virus, and Mycoplasma species. The basic structural characteristics of these infectious agents will be examined, along with their general pathogenic mechanisms. Coronavirus infections, such as caused by the SARS-CoV-2 virus, likely evolved from zoonotic bat viruses to infect humans and cause a pandemic that has been the biggest challenge for humanity since the Spanish Flu pandemic of the early 20th century. In contrast, Zika Virus infections represent an expanding infectious threat in the context of global climate change. The relationship of these infections to pregnancy, the vertical transmission and neurological sequels make these viruses highly relevant to the topics of this special issue. Finally, mycoplasmal infections have been present before mankind evolved, but they were rarely identified as human pathogens until recently, and they are now recognized as important coinfections that are able to modify the course and prognosis of various infectious diseases and other chronic illnesses. The infectious processes caused by these intracellular microorganisms are examined as well as some general aspects of their pathogeneses, clinical presentations, and diagnoses. We will finally consider examples of treatments that have been used to reduce morbidity and mortality of these infections and discuss briefly the current status of vaccines, in particular, against the SARS-CoV-2 virus. It is important to understand some of the basic features of these emerging infectious diseases and the pathogens involved in order to better appreciate the contributions of this special issue on how infectious diseases can affect human pregnancy, fetuses and neonates.