Intramammary administration of lipopolysaccharides at parturition enhances immunoglobulin concentration in goat colostrum.

In newborn ruminants, transfer of passive immunity is essential to obtain protection against pathogens. This study aimed to increase the permeability of the blood-milk barrier using intramammary lipopolysaccharides (LPS) in goats at parturition to modulate colostrum composition. Twenty multiparous Majorera dairy goats were randomly allocated in one of the two experimental groups. The LPS group (n = 10) received an intramammary administration (IA) of saline (2 mL) containing 50 µg of LPS from Escherichia coli (O55:B5) in each half udder at parturition. The control group (n = 10) received an IA of saline (2 mL). Rectal temperature (RT) was recorded, and a blood sample was collected at parturition (before IA). In addition, RT was measured, and blood and colostrum/milk samples were collected on day (d) 0.125 (3 hours), 0.5 (12 hours), 1, 2, 4, 7, 15 and 30 relative to the IA. Goat plasma immunoglobulin G (IgG) and M (IgM) and serum ß-hydroxybutyrate, glucose, calcium, free fatty acids, lactate dehydrogenase and total protein concentrations were determined. Colostrum and milk yields as well as chemical composition, somatic cell count (SCC), IgG and IgM concentrations were measured. The MIXED procedure (SAS 9.4) was used, and the model included the IA, time, and the interaction between both fixed effects. Statistical significance was set as P < 0.05. Goats from the LPS group showed higher RT on d 0.125, 0.5 and 4 relative to the IA compared to the control group (PIA×Time = 0.007). Goat serum biochemical variables and plasma IgG and IgM concentrations were not affected by the IA. Colostrum and milk yield as well as chemical composition were not affected by the IA, except for milk lactose percentage that was lower in the LPS group compared to the control group (4.3 ± 0.08 and 4.6 ± 0.08%, respectively PIA = 0.026). Colostrum SCC was higher in the LPS group than in the control group (3.5 ± 0.09 and 3.1 ± 0.09 cells × 106/mL, respectively; PIA = 0.011). Similarly, milk SCC increased in the LPS group compared to the control group (PIA = 0.004). The LPS group showed higher IgG (PIA = 0.044) and IgM (PIA = 0.037) concentrations on colostrum than the control group (31.9 ± 4.8 and 19.0 ± 4.8 mg/mL, 0.8 ± 0.08 and 0.5 ± 0.08 mg/mL, respectively). No differences in milk IgG and IgM concentrations between groups were observed. In conclusion, the IA of LPS at parturition increases RT, SCC and IgG and IgM concentrations in colostrum without affecting either yield or chemical composition.

Feeding milk supplemented with Ulva sp., Ascophyllum nodosum, or Saccharina latissima to preweaning dairy calves: Effects on growth, gut microbiota, gut histomorphology, and short-chain fatty acids in digesta.

Emerging knowledge shows the importance of preweaning nutrition on programming the gastrointestinal microbiome and development of the gut barrier function. The aim of this study was to assess the effects of supplementing cow milk with either intact dried Ulva sp., Ascophyllum nodosum, or Saccharina latissima on growth performance and several gut health parameters of preweaning dairy calves. Forty male Holstein calves were selected based on birth weight (41 ± 4 kg) and plasma Brix percentage (≥8.7%) at d 2 of life. From d 2 to d 42 of life, the control calves (n = 10) were fed with cow milk (8 L/d) without seaweed supplementation, and the experimental calves were fed with cow milk (8 L/d) supplemented with either Ulva sp. (n = 10), A. nodosum (n = 10), or S. latissima (n = 10) at a concentration of 50 g/8 L of cow milk per day (i.e., 5% on a dry matter basis). Calves were weighed every week, and body weight gain and calf starter intake were monitored weekly. At d 42 ± 3 of life, calves were slaughtered. The organ weights and digesta pH from the reticulorumen, mid- and end small intestine, and mid-colon were recorded. A tissue sample (5 cm) collected from the mid-small intestine was analyzed for histomorphology. Digesta from the mid-small intestine and mid-colon were analyzed for lactobacilli, Escherichia coli, and Enterobacteriaceae, and short-chain fatty acid profile. Weight gain of the calves was not affected by seaweed supplementation. Proportional organ weights were not affected by seaweed supplementation except for reticulorumen weight, which was higher in calves fed Ulva sp. Both the mid-small intestinal and mid-colonic digesta populations of lactobacilli, Enterobacteriaceae, and E. coli, as well as the mid-small intestinal histomorphology in seaweed-supplemented calves were not different from control calves. However, acetic acid proportion in mid-colonic digesta was increased in calves fed Ulva sp. and A. nodosum, whereas butyric acid proportion was decreased compared with the control calves. Digesta pH in mid- and end small intestine and mid-colon were not affected, whereas ruminal pH was increased in calves fed Ulva sp. compared with the control calves. In conclusion, intact dried seaweed supplementation did not improve the growth or selected gut health parameters (i.e., histomorphology, digesta pH, bacteria, and short-chain fatty acids) in preweaning Holstein calves.

Daily alternation of the dietary starch level in Holstein dairy cows.

The aim of this study was to investigate the effect of controlled daily alternations in dietary starch level on changes in rumen environment, blood, urine, and milk metabolites of dairy cows. Six multiparous mid-lactation Holstein cows were used in a replicated 3 × 3 Latin square design with 14-d periods and 3 alternating levels of dietary starch as treatments. Each 14-d period consisted of a 7-d baseline period and 7-d alternating period where diets alternated day to day. During the baseline period, all cows were fed a control diet containing 21% starch (dry matter basis). During the alternating period, the control diet was replaced with 1 of the 3 experimental diets on d 8, 10, 12, and 14. The 3 experimental diets contained 28% (low), 35% (medium), and 42% (high) starch (dry matter basis). At d 7 (baseline), 8 (ALT1), and 14 (ALT4) of each period, rumen fluid, blood, urine, and quarter milk (i.e., back right quarter) samples were collected at -0.5, 1, 2.5, 4, 5.5, and 7 h relative to morning feeding (0800 h). No differences were observed in dry matter intake, milk yield, and milk chemical composition. Rumen medial pH was lower in the high alternation level compared with the low or medium alternation levels at ALT1 but did not differ among starch alternation levels at ALT4. Similarly, the difference between rumen pH in medial and ventral contents was reduced at ALT1 with high alternation level but was not affected at ALT4. Total volatile fatty acid (VFA) concentrations were higher in the rumen medial fluid of the high alternation level at 7 h relative to morning feeding compared with those from the low and medium alternation levels. Similarly, total VFA concentrations constantly increased and were the highest in the ventral rumen fluid at 7 h relative to morning feeding, although no differences were detected among starch alternation levels. In both rumen medial and ventral fluids, the high alternation level showed higher propionate and lower acetate proportions compared with low and medium alternation levels. No differences in blood pH were detected among starch alternation levels. However, glucose concentrations tended to be higher in cows from the high alternation level. l-Lactate concentrations in blood were higher in ALT1 than in ALT4 but were not affected by the starch alternation level. In urine, no differences in pH or l-lactate concentrations were detected among alternation levels (i.e., low, medium, and high). Similarly, no differences in milk pH were detected among alternation levels. According to these results, it seems that the daily dietary starch alternation from 21% up to 42% (dry matter basis) is able to affect the ruminal fluid, especially during the first alternation. However, these changes in rumen fluid did not cause any effect on the variables measured in blood, urine, or milk. This study indicates that cows can cope with day-to-day alternations in type of rumen fermentable organic matter; however, longer-term effects on performance and health should be addressed in future studies.

Milk supplemented with dried seaweed affects the systemic innate immune response in preweaning dairy calves.

Intact seaweed or seaweed extracts are used as feed supplements to improve the gut microbiome in young animals. Seaweeds provide functional polysaccharides, and they are a good source of vitamins, minerals, and phenolic compounds, all of which are relevant for immune system development. However, literature on the effects of dried seaweed supplementation on immune system development is limited, especially in calves. This experiment aimed to study the effect of feeding milk supplemented with Ulva lactuca, Ascophyllum nodosum, or Saccharina latissima on the systemic immune status of preweaning dairy calves. Forty male Holstein calves with birth body weight 41 ± 4 kg and plasma Brix percentage ≥8.7% at d 2 after birth were used in this study. Calves were fed 4 L of cow milk twice a day (total 8 L/d). From d 2 to d 28, calves in the control group (n = 10) received milk without seaweed supplementation. Over the same period, experimental calves received milk supplemented with Ulva lactuca (SW1; n = 10), Ascophyllum nodosum (SW2; n = 10), or Saccharina latissima (SW3, n = 10). Dried and ground seaweeds were offered at a daily allowance of 50 g/8 L of milk (i.e., approximately 5% inclusion rate on a dry matter basis). Blood samples were collected from a jugular vein on d 2, 4, 7, 14, 21, and 28 after birth. Plasma concentrations of total protein, albumin, immunoglobulins, and acute-phase proteins (i.e., serum amyloid A, fibrinogen, and haptoglobin) were measured. We detected no differences in average daily gain, plasma immunoglobulins, albumin, or total protein. However, the contrast analysis revealed that plasma concentrations of fibrinogen (SW1 and SW2) and serum amyloid A (SW2 and SW3) were significantly higher in the seaweed groups compared with the control group. We also found a tendency for high plasma haptoglobin in the seaweed groups (SW1 and SW2) compared with the control group. Differences in acute-phase protein concentrations could be partially explained by the large differences in micromineral intake between control and seaweed-supplemented calves. Feeding milk supplemented with dried seaweed increased plasma concentrations of variables related to the innate immune response in preweaning dairy calves.

Oral administration of lipopolysaccharides from Escherichia coli (serotype O111:B4) does not induce an effective systemic immune response in milk-fed Holstein calves.

It is well established that intravenous administration of lipopolysaccharides (LPS)-cell wall components from gram-negative bacteria-induce acute inflammatory responses in dairy calves, but the effect of oral administration of LPS to dairy calves is currently unknown. To evaluate the effects of oral administration of LPS derived from Escherichia coli (serotype O111:B4) on innate immune responses in milk-fed Holstein calves, 20 visually healthy calves (34 ± 1 d) received 4 L of milk with LPS (12 µg/kg body weight; n = 10; LPS) or without LPS (n = 10; control) at the morning feeding. Samples were collected at 0.5 h before the morning feeding and at 3, 6, 24, 48, 72, and 168 h after the morning feeding to measure rectal temperature and heart rate, as well as plasma-negative and plasma-positive acute phase proteins (i.e., haptoglobin, serum amyloid A, albumin, total protein, and fibrinogen) and immunoglobulin concentrations (IgG, IgM, and IgA). None of these measurements was affected by the oral administration of LPS. Oral administration of LPS at 12 µg/kg of body weight did not induce an acute inflammatory response in visually healthy milk-fed Holstein calves when administered in milk.

Review: Endocrine pathways to regulate calcium homeostasis around parturition and the prevention of hypocalcemia in periparturient dairy cows.

Calcium homeostasis is crucial for the normal function of the organism. Parathyroid hormone, calcitriol and calcitonin play critical roles in the homeostatic regulation of calcium. Serotonin and prolactin have also been shown to be involved in the regulation of calcium homeostasis. In modern dairy cows, the endocrine pathways controlling calcium homeostasis during non-lactating and non-pregnant physiological states are unable to fully support the increased demand of calcium required for milk synthesis at the onset of lactation. This review describes different endocrine systems associated with the regulation of calcium homeostasis in mammalian species around parturition with special focus on dairy cows. Additionally, classic and novel strategies to reduce the incidence of hypocalcemia in parturient dairy cows are discussed.

Use of glycerol and propylene glycol as additives in heat-treated goat colostrum.

This experiment aimed to evaluate the suitability of glycerol and propylene glycol to reduce microbial count and preserve immune properties in heat-treated goat colostrum. Colostrum samples from 11 goats were each divided into 9 aliquots. Different concentrations (2, 6, 10, and 14%; vol/vol) of either glycerol or propylene glycol were added to the aliquots. Phosphate buffer solution was added to one aliquot, which was set as the control (CG). After the respective additions, all colostrum samples were heat treated at 56°C for 1 h. After cooling, aerobic mesophilic bacteria were cultured. The samples were frozen until free fatty acid, IgG, IgA, and IgM concentrations and chitotriosidase activity were measured. No differences were found in aerobic mesophilic bacteria counts between either 10 or 14% glycerol and propylene glycol additives. These additions reduced bacterial count to a greater extent than CG, and 2 or 6% additions. Colostrum IgG concentration was not affected by either of the additives or their concentrations. The propylene glycol additive reduced IgA and IgM concentrations and chitotriosidase activity, compared with CG. Conversely, glycerol did not affect any of the studied immune variables. In conclusion, glycerol addition to goat colostrum before heat treatment is suitable to enhance bacterial reduction, whereas colostrum immune properties were not affected.

Prepartum daylight exposure increases serum calcium concentrations in dairy cows at the onset of lactation.

In dairy cows, hypocalcemia is caused by the sudden calcium demand by the mammary gland at the onset of lactation. Calcitriol (1,25-dihydroxy vitamin D; 1,25-VitD) increases the intestinal calcium absorption and the renal calcium reabsorption. Daylight contributes to the formation of 1,25-VitD, as it transforms 7-dehydrocholesterol into cholecalciferol, a 1,25-VitD precursor. Calving pens are usually set in quiet places where cows can stay calm and relaxed before parturition. However, those pens often have poor lighting conditions and therefore cows may become vitamin D deficient because of inadequate daylight exposure. Therefore, we have tested the hypothesis that direct daylight exposure supports the synthesis of 1,25-VitD and consequently attenuates the decline of calcium concentrations at parturition. Twenty Holstein dairy cows were randomly assigned to 2 experimental groups (daylight group, DL; and control group). Beginning on d -10 before expected parturition, both groups were placed in a standard indoor calving pen from 1700 h to 800 h. From 800 h to 1700 h cows from the DL group were moved into a contiguous open pen with direct access to daylight whereas controls remained at the standard indoor calving pen. After parturition both groups were permanently placed in an indoor calving pen until the end of the experimental period (d 30 postpartum). Blood samples were collected daily from d -10 prior to expected parturition through d 7 postpartum with an additional sample on d 30 postpartum. Milk yield was recorded at each milking during the whole experimental period. In the DL group, 25-hydroxyvitamin D (25-VitD), 1,25-VitD and total calcium concentrations around parturition were higher than in the controls. Higher parathyroid hormone concentrations were observed in the control group compared to the DL group at parturition. Pyridinoline concentrations did not differ between groups on d 1, and therefore it is assumed that the intensity of calcium transfer from the bones to the bloodstream was not affected by the increased daylight exposure. The measured plasma metabolites (ß-hydroxybutyrate, fatty acids and glucose) as well as milk yield were not affected by the increased daylight exposure. In conclusion, the increased daylight exposure before parturition increased 25-VitD and 1,25-VitD concentrations, preventing a considerable decline of total calcium concentrations around parturition.

Trichomonas vaginalis exosome-like vesicles modify the cytokine profile and reduce inflammation in parasite-infected mice.

Trichomonas vaginalis (Tv) is a flagellated parasite commonly spread through sexual transmission. This protozoan initiates a severe inflammatory process, inducing nitric oxide, interleukin-6 (IL-6), IL-8, IL-10, IL-17 and IL-22 production by host immune cells. The parasites elicit these responses by releasing surface lipophosphoglycan, small extracellular vesicles (exosomes) and other factors. Tv exosomes are similar to mammalian exosomes and have been implicated in the modulation of IL-8 secretion by epithelial cells. Here, we report that exosome-like vesicles from T. vaginalis (Tv-ELVs) induced a more than 15-fold increase in IL-10 expression in RAW264.7 macrophages but only a two fold increase in IL-6 and TNF-α expression levels measured by RT-PCR. Because Tv-ELVs modulated the macrophage response, we also explored the effect of Tv-ELVs in a murine model of infection. Pretreatment with Tv-ELVs significantly increased IL-10 production as measured in vaginal washes by days 8 and 16 post-infection. Remarkably, Tv-ELVs-pretreated mice exhibited a decrease in IL-17 production and a significant decrease in vulvar inflammation. In addition, IL-6 and IL-13 were decreased during infection. Our results suggest that Tv-ELVs have an immunomodulatory role on the cytokine profile induced by the parasite and promote a decrease in the inflammatory process in mice infected with T. vaginalis.

The effect of colostrum period management on BW and immune system in lambs: from birth to weaning.

The aim of this study was to investigate the BW and immune status of lambs reared under natural conditions or under artificial conditions fed two different colostrum amounts. In this study, 60 lambs were randomly divided into groups according to treatment. Twenty lambs remained with their dams (natural rearing (NR) group). Forty lambs were removed from their dams at birth. Lambs were bottle-fed with a pool of sheep colostrum, receiving either 4 g of IgG/kg of BW at birth (C4 group) or 8 g of IgG/kg of BW at birth (C8 group). The total colostrum amount was equally divided into three meals at 2, 14 and 24 h after birth. After this period, lambs were bottle-fed a commercial milk replacer. Blood plasma sample analysis and BW recordings were carried out before feeding at birth and then at 1, 2, 3, 4, 5 and 20 days after birth. Another blood sample analysis and BW recording was carried out when animals reached 10 kg of BW. During weaning (30 days), sampling was carried out every 5 days. Blood plasma was used to determine the concentrations of IgG and IgM and the complement system activity - total and alternative pathways. The NR group showed greater BW than the C4 and C8 groups during milk feeding period, whereas the C4 and C8 groups had greater BW than the NR group at the end of weaning period. The C8 and NR groups had greater plasma IgG and IgM concentrations than the C4 group during milk feeding period. In addition, C4 and C8 groups showed similar IgG concentrations and greater IgM concentrations than the NR group at the end of the weaning period. Complement system activity was greater in the NR group than in the C4 and C8 groups during the first 3 days after birth. In conclusion, lambs fed amounts of colostrum equivalent to 8 g of IgG/kg of BW showed similar immune variables compared to lambs reared under natural conditions, obtaining a greater BW at the end of the weaning period. Nevertheless, this study shows that not only the colostrum amount but also the management during the milk feeding and weaning period, such as stress produced by dam separation, milk quality and suckling frequency, can affect the final immune status of lambs.

The effect of colostrum source (goat vs. sheep) and timing of the first colostrum feeding (2h vs. 14h after birth) on body weight and immune status of artificially reared newborn lambs.

Several factors can affect lamb body weight (BW) and immune status during the first days of life, including colostrum source and timing of the first colostrum feeding. The aim of this study was to evaluate the effects of colostrum source (goat or sheep) and timing of the first colostrum feeding (2 or 14h after birth) on lamb BW and immune status. In this study, 40 lambs were removed from their dams at birth and randomly assigned into 4 groups of 10 lambs each. Lambs were subsequently fed at 2 or 14h after birth with goat or sheep colostrum. Blood samples and BW recording were performed before feeding. Blood plasma was used to measure the immunoglobulin concentration (IgG and IgM), chitotriosidase activity, and complement system activity (total and alternative pathways). In general, no differences in any of the measured variables were observed among the 4 groups, indicating that neither colostrum source nor timing of the first colostrum feeding had an effect on these variables. These findings may improve management on lamb farms that raise animals under artificial conditions, because our results indicate that it is not necessary to feed colostrum to lambs immediately after birth and that goat colostrum may be used to feed newborn lambs.

Short communication: Effects of milking frequency on udder morphology, milk partitioning, and milk quality in 3 dairy goat breeds.

Thirty-six dairy goats of 3 breeds (Majorera, Tinerfeña, and Palmera) in mid lactation (124 ± 8 d in milk) were subjected unilaterally to once (× 1) or twice daily milking (× 2) for 5 wk to evaluate udder morphology, milk partitioning, and somatic cell count. Majorera and Palmera goats presented the highest and lowest udder depth values, respectively, whereas the differences between initial and final cistern-floor and teat-floor distances were not affected by milking frequency or breed factors. Cisternal and alveolar milk percentages were similar between × 1 and × 2 in the studied breeds. Milking frequency did not affect milk composition in the cisternal fraction, suggesting a greater transfer of milk from the alveoli to the cistern during early udder filling. However, milking frequency caused diverse changes in the milk composition in the alveolar fraction, especially in fat, lactose, and total solids contents. No udder halves presented clinical mastitis during the experimental period, suggesting that × 1 does not impair udder health and indicating that the studied breeds are adapted to this milking frequency.

Docosahexaenoic acid in the goat kid diet: effects on immune system and meat quality.

The effect of dietary docosahexaenoic acid (C22:6n3; DHA) supplementation on meat quality and immunity in goat (Capra hircus) kids was examined. Goat kids (n = 30) were fed 1 of 3 experimental diets: goat milk (GM), cow (Bos taurus) milk (CM), and CM supplemented with DHA (CM-DHA). Animals were fed ad libitum twice daily and weighed twice each week. Blood samples were collected by jugular venipuncture daily during the first 10 d of life and were subsequently collected every 5 d until slaughter at a BW of 8 kg. Carcass size (linear measurements) and weight, as well as meat pH, color, tenderness, and chemical composition were determined. Fatty acid profiles of intramuscular, peri-renal, pelvic, subcutaneous, and intermuscular fats were analyzed. Blood IgG and IgM concentrations, complement system activity (classical and alternative pathways), and chitotriosidase activity were recorded. Results indicated that the diet containing DHA did not affect (P > 0.05) carcass linear measurements, meat quality characteristics, or proximate composition of the meat. However, C22:6n3 fatty acid levels, mainly in intramuscular fat, were enriched (P < 0.05) in CM-DHA animals, and the n-6 to n-3 PUFA ratio was improved (P < 0.05). No differences (P > 0.05) in immune function were observed among groups. In conclusion, powdered whole CM is an effective option for feeding goat kids, and the inclusion of DHA to CM increases the quantity of this fatty acid in the meat.

Lipolysis and proteolysis profiles of fresh artisanal goat cheese made with raw milk with 3 different fat contents.

The objective of this study was to describe the proteolysis and lipolysis profiles in goat cheese made in the Canary Islands (Spain) using raw milk with 3 different fat contents (0.5, 1.5, and 5%) and ripened for 1, 7, 14, and 28 d. ß-Casein was the most abundant protein in all cheeses and at all ripening times. Quantitative analysis showed a general decrease in caseins as ripening progressed, and degradation rates were higher for α(S1)-casein than for ß-casein and α(S2)-casein. Furthermore, the degradation rate during the experimental time decreased with lower fat contents. The α(S2)-casein and α(S1)-casein levels that remained in full-fat and reduced-fat cheeses were less than those in low-fat cheese. In contrast, ß-casein also showed degradation along with ripening, but differences in degradation among the 3 cheese types were not significant at 28 d. The degradation products increased with the ripening time in all cheeses, but they were higher in full-fat cheese than in reduced-fat and low-fat cheeses. The free fatty acid concentration per 100g of cheese was higher in full-fat cheese than in reduced- and low-fat cheese; however, when the results were expressed as milligrams of free fatty acids per gram of fat in cheese, then lipolysis occurred more rapidly in low-fat cheese than in reduced- and full-fat cheeses. These results may explain the atypical texture and off-flavors found in low-fat goat cheeses, likely the main causes of non-acceptance.

Effects of feeding management and time of day on the occurrence of self-suckling in dairy goats.

The occurrence of self-suckling was recorded in 21 dairy goats during periods of 20 minutes at three different times per day (immediately after milking and the first feed, immediately after the second feed and in the afternoon) for 27 days (divided into three experimental periods of nine days). As expected, negative associations between milk yield and the frequency of self-suckling were observed (P<0.05). Goats suckled on their own right teat more frequently than on the left teat. The width of the right teat (measured at the middle of the teat) was positively associated with the frequency of self-suckling after controlling for the width of the left teat. A higher self-suckling frequency was observed immediately after milking than in the other two periods of the day. The frequency of self-suckling by each goat was reduced when animals were supplemented ad libitum with wheat straw in addition to their ordinary feed.

Sodium dodecyl sulfate reduces bacterial contamination in goat colostrum without negative effects on immune passive transfer in goat kids.

To investigate the use of sodium dodecyl sulfate (SDS) as a biocide on goat colostrum, 2 experiments were performed. In the first, 20 goat colostrum samples were divided into 3 aliquots. A different treatment was performed on each aliquot: pasteurization (56°C, 30 min) or addition of SDS to a final concentration of either 0.1 or 1% (36°C, 10 min). Immunoglobulin G and colony-forming units were evaluated before and after treatment. Both pasteurization and treatment with 1% SDS significantly reduced the colony-forming units in colostrum. Treatment with 0.1% SDS was not effective at reducing the colony-forming units in colostrum. The IgG concentration of pasteurized colostrum was significantly lower than that of untreated colostrum, whereas treatment with 1% SDS did not affect the colostrum IgG concentration. In the second experiment, the effects of SDS colostrum treatment on immune passive transfer were evaluated. Forty goat kids were fed either refrigerated colostrum or colostrum treated with 1% SDS twice daily for 2 d. Blood samples were obtained at birth and every day for 5 d. IgG, IgM, and IgA were measured in blood serum to monitor the passive immune transfer process. Creatinine, glucose, total cholesterol, blood urea nitrogen, bilirubin, and aspartate transaminase were also monitored to evaluate the health of kids. No differences in serum IgG, IgM, IgA, creatinine, glucose, total cholesterol, blood urea nitrogen, bilirubin, or aspartate transaminase levels were observed between groups. Our findings indicate that SDS is an efficient colostrum biocide that, unlike pasteurization, does not affect immune passive transfer or goat kid health.

Subcellular localization of the GTP-binding protein Rho in the sea urchin sperm.

The Rho proteins are small G-proteins that belong to the Ras superfamily and play an essential role in the organization of the actin cytoskeleton. They are characteristically ADP-ribosylated by the exoenzyme C3 from Clostridium botulinum. Sea urchin sperm contain multiple small G proteins (28-24 kDa) whose identity and function are unknown. Here, we examined whether some of these proteins corresponded to the Rho subfamily. A sperm homogenate incubated with C3 and [32P]NAD revealed, by electrophoresis and autoradiography, a single radiolabeled band with a molecular mass of 25 kDa; this size was identical, under the same conditions, to that displayed by RhoA from human platelets. In flagellar fractions, the 25 kDa protein ADP-ribosylated by C3 localized in the cytosol and in the plasma membrane. In the sperm head, the 25 kDa protein was detected in a membrane preparation enriched in acrosomal and plasma membranes. Separation of these head membranes through a continuous density gradient revealed that both the 25 kDa protein [32P]ADP-ribosylated by C3 and actin had the same localization as bindin, the adhesive protein characteristic of the acrosome. An antibody against RhoB cross-reacted by immunoblotting with the 25 kDa protein and it revealed by both immunofluorescence and immunogold the presence of Rho in the acrosomal region, the middle piece of the head, and in the flagellum. Thus, the results indicate that the G-protein of 25 kDa previously detected in sea urchin sperm is Rho, likely the type B. Based on its cellular localization, Rho may participate in regulating motility and the actin polymerization that accompanies the acrosome reaction.

The acrosome reaction in digitonin-permeabilized sea urchin sperm in the absence of the natural inducer.

In many species, the acrosome reaction of sperm is an obligatory step in fertilization. Increases in [Ca2+]i and pHi, activation of adenylyl cyclase and inositol trisphosphate generation accompany the egg jelly-induced acrosome reaction of sea urchin sperm. The signaling mechanisms involved are unknown. We used digitonin, a cholesterol-complexing compound, to selectively permeabilize the plasma membrane of sea urchin sperm suspended in a medium that mimics the cytosolic ion composition. Within 6 to 8 min, 30 to 50 microM digitonin allowed incorporation of the membrane-impermeant dye Hoechst 33258 into the sperm, staining exclusively the nucleus. No alterations in sperm morphology were caused by digitonin at the concentrations used, however, it irreversibly permeabilized the plasma membrane. Permeabilized sperm retained lactate dehydrogenase and actin. When incubated in Ca(2+)-containing permeabilization buffer (pH 7.8), sperm were capable of undergoing spontaneously the acrosome reaction; this reaction was pH dependent and displayed an absolute Ca2+ requirement. Electron microscopy indicates that the acrosome reaction undergone by permeabilized sperm resembled that induced by egg jelly. Additionally, rhodaminyl-phalloidin staining of sperm reacted under permeabilizing conditions revealed a fluorescent filament in the acrosomal tubule region, demonstrating the occurrence of actin polymerization. Thus, in permeabilized sperm the machinery necessary to perform a [Ca2+]i- and pHi-sensitive acrosome reaction is functionally preserved. Permeabilized sperm offer new avenues to study the molecular bases of the sea urchin sperm acrosome reaction.