Immature Calves Research Articles

Ultrastructure of the Bovine Testis in Cattle (Bos taurus): New View.

The purpose of this study was to analyze the ultrastructure of the testes of sexually immature calves and reproductive bulls of the Polish Holstein-Friesian Black-and-White breed. Utilizing TEM, this study identified three distinct stages of seminiferous tubule development in calves, characterized by varying shapes, distributions, and arrangements of individual cells. In immature animals, early developing spermatocytes, prespermatogonia, and pre-Sertoli cells were observed within the seminiferous tubules. In sexually mature bulls, all cells of the spermatogenic series were observed, situated on a thin, multilayered basal lamina, which forms characteristic undulations. An abundant smooth endoplasmic reticulum was observed in the cytoplasm of spermatogonia in both groups of animals, forming characteristic membranous swirls. In adult bulls, spermatogonia maintain contact with each other through numerous cytoplasmic bridges and cell connections, forming small spaces with visible microvilli between them. The ultrastructural analysis facilitated the identification of morphological changes occurring during the maturation of pre-Sertoli cells, transitioning from a large euchromatic nucleus to a nucleus in which the formation of characteristic vesicles and tubules could be observed. It should also be emphasized that two types of Sertoli cells, namely dark and light electron-dense cells, can be found in cattle. These cells differ from each other, indicating that they may perform different functions. The widespread recognition of the presence of two types of Sertoli cells in cattle will undoubtedly contribute to a better understanding of the processes occurring within the testes and provide a basis for further research in this area.

Influence of autolyzed yeast on the health of immunologically immature calves

Autolyzed yeast is a supplement option for calves due to its ability to stimulate the immune system and performance; however, there are few studies about the effect of different yeast derivatives. Autolyzed yeast is rich in immunomodulatory substances, such as mannan oligosaccharides and β-glucans. These substances enhance the innate and humoral immunity of calves, resulting in greater intestinal and respiratory health. Thus, the objective of the study was to evaluate whether supplementation with autolyzed yeast improves the health of calves, in the challenge of naturally acquired Eimeriosis and bovine respiratory disease (BRD). Twenty Holstein calves aged 15 days, which had already suckled colostrum, were studied for 36 days. At 15 days of life all animals had naturally acquired Eimeriosis. They were challenged with an intranasal BRD vaccine at 30 days of age. The Supplemented group (n=10) received autolyzed yeast (10 g animal -1 day -1), once a day in milk for 36 days, and the Control group (n=10) was not supplemented throughout the experiment. Blood neutrophil: lymphocyte ratio, oxidative metabolism of neutrophils (OM), serum immunoglobulins and haptoglobin, occurrence of diarrhea, BRD, and weight gain were measured. After vaccination, all animals increased the blood neutrophil: lymphocyte ratio, but only the control group showed a 20% reduction in OM three days after the vaccine. The supplement affected the immune response, preserving OM, increasing serum IgA levels by 10% (P=0.006), and reducing haptoglobin serum levels (P=0.05). In addition, the supplement attenuated diarrhea and BRD, which allowed for greater weekly weight gain (difference of 2 kg between treatments, P<0.05), concluding that the autolyzed yeast showed some evidence that it can increase the health of calves challenged with Eimeriosis and the BRD vaccine.

A Comprehensive Sequencing Analysis of Testis-Born miRNAs in Immature and Mature Indigenous Wandong Cattle (Bos taurus).

Micro RNAs (miRNAs) have been recognized as important regulators that are indispensable for testicular development and spermatogenesis. miRNAs are endogenous transcriptomic elements and mainly regulate the gene expression at post-transcriptional levels; however, the key role of miRNA in bovine testicular growth is not clearly understood. Thus, supposing to unveil the transcriptomics expression changes in the developmental processes of bovine testes, we selected three immature calves and three sexually mature bulls of the local Wandong breed for testicular-tissue sample collection. The cDNA libraries of experimental animals were established for RNA-sequencing analysis. We detected the miRNA expression in testes by using high-throughput sequencing technology, and bioinformatics analysis followed. The differentially expressed (DE) data showed that 151 miRNAs linked genes were significantly DE between immature and mature bull testes. Further, in detail, 64 were significantly up-regulated and 87 were down-regulated in the immature vs. mature testes (p-value < 0.05). Pathway analyses for miRNA-linked genes were performed and identified JAG2, BCL6, CFAP157, PHC2, TYRO3, SEPTIN6, and BSP3; these genes were involved in biological pathways such as TNF signaling, T cell receptor, PI3KAkt signaling, and functions affecting testes development and spermatogenesis. The DE miRNAs including MIR425, MIR98, MIR34C, MIR184, MIR18A, MIR136, MIR15A, MIR1388 and MIR210 were associated with cattle-bull sexual maturation and sperm production. RT-qPCR validation analysis showed a consistent correlation to the sequencing data findings. The current study provides a good framework for understanding the mechanism of miRNAs in the development of testes and spermatogenesis.

Immune, health, and growth responses of beef calves administered modified-live virus respiratory vaccine in the presence of maternal antibody versus a traditional vaccination regimen

Typical preconditioning guidelines recommend that calves be vaccinated against respiratory and other pathogens at or near weaning (~205 days) because of the historical belief that maternal antibodies from colostrum ingested by the neonatal calf may interfere with the immune response to vaccination. However, recent research investigating vaccination during the presence of maternal antibodies suggests that neonatal calves vaccinated with a modified-live virus (MLV) vaccine are protected from subsequent BVDV challenge and immature calves vaccinated at 67 days of age develop both an initial and anamnestic antibody response. Our objective was to determine the effects of administration of a pentavalent MLV respiratory vaccine to calves at approximately 60 days of age versus at a traditional vaccination regimen age (near weaning) on health, growth performance, and BVDV type la-specific antibody titers and T cell activation.

Electrophoretic and immunoelectrophoretic characteristics of IgG as a constituents of peg precipitable immune complexes in preruminant calves' sera

Preruminant calves encounter numerous antigens, and formation of immune complexes is necessary for antigens elimination. The capability of immunologically immature calves to form immune complexes has not yet been studied in detail. For immune complexes studies, selective precipitation by PEG was performed, in combination with agarose gel electrophoresis and immunoelectrophoresis, with an aim to determine some properties of IgG, as constituents of immune complexes. In our previous work it was shown that the level of PEG precipitable immune complexes increased in the period from birth to 48-hours of life, decreased at day 10, increased in one month old animals, and after that, stayed unchanged until 4th month of age. Electrophoretic and immunoelectrophoretic analysis showed that until one month of age, calves' sera and PEG precipitates contained only one part of IgG molecules which corresponded to fast, anionic γ globulins. Although at the age of one month, preruminant calves' sera contained all molecular forms of IgG molecules present in the sera of adult cattle, only one part of serum IgG (fast, anionic IgG) was precipitated by PEG. In older calves, all molecular forms of serum IgG had the capacity to form PEG precipitable immune complexes. Presented data, as well as the results of our previous work, can be used as parameters with reference to physicochemical and immunochemical characteristics of IgG immune complexes of preruminant calves under pathological conditions.

Perfluoroalkyl compounds in relation to life‐history and reproductive parameters in bottlenose dolphins (Tursiops truncatus) from Sarasota Bay, Florida, USA

Perfluoroalkyl compounds (PFCs) were determined in plasma, milk, and urine of free-ranging bottlenose dolphins (Tursiops truncatus) from Sarasota Bay (FL, USA) during three winter and two summer capture-and-release programs (2002-2005). Plasma and urine samples were extracted using an ion-pairing method. Perfluoroalkyl compounds were extracted from milk samples using acetonitrile, and extracts were cleaned with graphitized nonporous carbon. All extracts were analyzed by high-performance liquid chromatography-tandem mass spectrometry. Mean seasonal sum of PFCs (sigma PFCs) detected in dolphin plasma ranged from 530 to 927 ng/g wet weight. No significant differences (p > 0.05) were found in concentrations between seasons, suggesting a constant exposure to PFCs. Overall, blubber thickness of dolphins did not correlate with PFC concentrations in plasma, suggesting an absence of PFC sequestration in blubber. Sexually immature calves (age, <10 years; mean sigma PFCs, 1,410 +/- 780 ng/ g wet wt) were significantly more contaminated (p < 0.001) than their mothers (mean sigma PFCs, 366 +/- 351 ng/g wet wt). The reproductive history of females had a significant role in the burden of PFC contamination; PFC concentrations in nulliparous females (females that have not been observed with calves) were significantly greater than those detected in uniparous females (females that have been observed with one calf), suggesting an off-loading of PFCs during or after parturition. To investigate this hypothesis, PFCs were analyzed in milk samples (n=10; mean sigma PFCs, 134 +/- 76.1 ng/g wet wt), confirming a maternal transfer of PFCs through lactation in dolphins. Results from the present study showed that young and developing bottlenose dolphins are highly exposed to PFCs. These chemicals also were detected in urine (mean sigma PFCs, 26.6 +/- 79 ng/g wet wt), indicating that the urinary system is an important pathway of PFC depuration in dolphins.

SELCAB (Self-Lung Cardiac Bypass) Procedures for Pediatric Patients

Cardiopulmonary bypass (CPB) for pediatric heart surgeries is not ideal. The currently available systems have a priming volume of 400-1,200 ml, requiring substantial hemodilution. CPB also subjects immature lung tissue to unphysiologic conditions. Exposure of the pediatric patient's blood to the large surface areas of foreign materials associated with an oxygenator results in humoral and cellular impacts on the pediatric patient's immature organs and should be avoided. For selected cases of pediatric heart surgeries, the SELCAB (self-lung cardiac bypass) procedure would be advantageous over CPB. This procedure is equivalent to a biventricular assist device (BVAD) implantation. To distinguish this procedure from long-term BVAD, a BVAD implantation of less than 2 weeks is referred to as SELCAB. Also, the SELCAB's inflow cannulations are either in atria or veins, whereas BVAD inflow cannulations are in ventricles. Advantages and disadvantages of SELCAB are discussed. The physiologic acceptance of SELCAB procedures in immature calves (pediatric model), with beating and nonbeating natural hearts for as long as 3 months, is described. The SELCAB and BVAD systems developed by these authors are also described in this article.

Long-Term Growth after Hypophyseal Stalk Transection and Hypophysectomy of Beef Calves

Hypothalamic hormones regulate episodic and basal secretion of hormones from the anterior pituitary gland that affect metabolism and growth in cattle. This study focused on long-term growth in young calves subjected to hypophysectomy (HYPOX), hypophyseal stalk transection (HST), and sham operation control (SOC). Cross-bred (Hereford x Aberdeen Angus) and Hereford, and Aberdeen Angus calves were HYPOX (n = 5), HST (n = 5), or SOC (n = 8) at 146 ± 2 days of age, whereas another group was HST (n = 5) or SOC (n= 7) at 273 ± 5 days of age. Body weight was determined every 21 days from birth to 1008 days of age. Anterior vena cava blood was withdrawn at 4-day intervals from day 64–360 for RIA of GH, TSH, T4, T3, and LH, and at 20-min intervals for 480 min to determine episodic hormone secretion. Daily feed intake was determined in HST and SOC calves during an 80-day period. Birth weight averaged 35 ± 1 kg (± se) and was 142 ± 4 kg at 126 days and 208 ± 8 kg at 252 days before surgery. From day 146-1008, growth was arrested (P < 0.001) in HYPOX (0.06 ± 0.01 kg/day) compared with SOC (0.50 ± 0.04 kg/day) calves. Growth continued but at a significantly lower rate (P < 0.05) in calves HST at 146 days (0.32 ± 0.07 kg/day) and 273 days (0.32 ± 0.06 kg/day) compared with SOC (0.50 ± 0.09 kg/day). Growth continued to be impaired to 1008 days, but more so in those HST at 146 days (432 ± 43 kg BW) than 273 days (472 ± 5 kg BW) and less (P < 0.05) than SOC (586 ± 37 kg BW). Daily feed intake was consistently less (P < 0.05) in HST compared with SOC calves. Although episodic GH secretion was abolished and peripheral serum GH concentration remained consistently lower in HST (2.4 ng/ml) than SOC (5.5 ng/ml; P < 0.01), the calves continued to grow throughout 1008 days. Peripheral serum TSH concentration was less (P < 0.05) HST compared with SOC calves. There was an abrupt decrease (P < 0.001) in serum T4 (4-fold) and T3 (3-fold) concentration after surgery that remained to 360 days in HST compared with SOC calves. At the time calves were killed, pituitary gland weight was markedly reduced (P < 0.001) in HST (0.18 ± 0.01 g/100 kg BW) compared with SOC (0.54 ± 0.03 g/100 kg BW). Histological examination of pituitary glands from HST calves indicated the persistence of secretory GH and TSH cells in the same areas of the adenohypophysis as SOC calves. Coronal sections of the gland stained with performic acid-Alcian blue-periodic acid-Schiff-orange G, revealed GH and TSH secreting cells in HST calves similar to controls. These results indicate that long-term growth continues, but at a slower rate, after hypophyseal stalk transection of immature calves in spite of complete abolition of episodic GH secretion and consistently decreased basal secretion of GH, TSH, T4, and T3 compared with sham-operated animals. Growth was abolished after hypophysectomy of immature calves in which circulating GH and TSH was undetectable.

Long-term growth after hypophyseal stalk transection and hypophysectomy of beef calves.

Hypothalamic hormones regulate episodic and basal secretion of hormones from the anterior pituitary gland that affect metabolism and growth in cattle. This study focused on long-term growth in young calves subjected to hypophysectomy (HYPOX), hypophyseal stalk transection (HST), and sham operation control (SOC). Cross-bred (Hereford x Aberdeen Angus) and Hereford, and Aberdeen Angus calves were HYPOX (n = 5), HST (n = 5), or SOC (n = 8) at 146 +/- 2 days of age, whereas another group was HST (n = 5) or SOC (n = 7) at 273 +/- 5 days of age. Body weight was determined every 21 days from birth to 1008 days of age. Anterior vena cava blood was withdrawn at 4-day intervals from day 64-360 for RIA of GH, TSH, T4, T3, and LH, and at 20-min intervals for 480 min to determine episodic hormone secretion. Daily feed intake was determined in HST and SOC calves during an 80-day period. Birth weight averaged 35 +/- 1 kg (+/- SE) and was 142 +/- 4 kg at 126 days and 208 +/- 8 kg at 252 days before surgery. From day 146-1008, growth was arrested (P < 0.001) in HYPOX (0.06 +/- 0.01 kg/day) compared with SOC (0.50 +/- 0.04 kg/day) calves. Growth continued but at a significantly lower rate (P < 0.05) in calves HST at 146 days (0.32 +/- 0.07 kg/day) and 273 days (0.32 +/- 0.06 kg/day) compared with SOC (0.50 +/- 0.09 kg/day). Growth continued to be impaired to 1008 days, but more so in those HST at 146 days (432 +/- 43 kg BW) than 273 days (472 +/- 5 kg BW) and less (P < 0.05) than SOC (586 +/- 37 kg BW). Daily feed intake was consistently less (P < 0.05) in HST compared with SOC calves. Although episodic GH secretion was abolished and peripheral serum GH concentration remained consistently lower in HST (2.4 ng/ml) than SOC (5.5 ng/ml; P < 0.01), the calves continued to grow throughout 1008 days. Peripheral serum TSH concentration was less (P < 0.05) HST compared with SOC calves. There was an abrupt decrease (P < 0.001) in serum T4 (4-fold) and T3 (3-fold) concentration after surgery that remained to 360 days in HST compared with SOC calves. At the time calves were killed, pituitary gland weight was markedly reduced (P < 0.001) in HST (0.18 +/- 0.01 g/100 kg BW) compared with SOC (0.54 +/- 0.03 g/100 kg BW). Histological examination of pituitary glands from HST calves indicated the persistence of secretory GH and TSH cells in the same areas of the adenohypophysis as SOC calves. Coronal sections of the gland stained with performic acid-Alcian blue-periodic acid-Schiff-orange G, revealed GH and TSH secreting cells in HST calves similar to controls. These results indicate that long-term growth continues, but at a slower rate, after hypophyseal stalk transection of immature calves in spite of complete abolition of episodic GH secretion and consistently decreased basal secretion of GH, TSH, T4, and T3 compared with sham-operated animals. Growth was abolished after hypophysectomy of immature calves in which circulating GH and TSH was undetectable.

Comparative Effects of Fixation and Storage on Bone Tetracycline Fluorescence

SummaryAs an adjunct to an ongoing project, ends of longbones, including the growth plate, were collected from tetracycline labelled immature rabbits and calves. Samples were stored from a few days up to two months at room temperature, refrigerator temperature (+4°C), –20°C, or –70°C, and unfixed, formalin-fixed or alcohol-fixed. Qualitative and quantitative aspects of cut sections were evaluated. Freezing resulted in the least alteration. Fixed bone samples (alcohol or formalin) all progressively discoloured with increasing storage. Comparison between fresh, stored and differently fixed sections did not identify any change in the measured distance between labels; though the clarity of the labels was affected. Formalin fixation and storage did not result in mark degradation nor alteration of the labels.Tetracycline fluorescence, in labelled growth plates, was evaluated following storage from a few days up to two months at various temperatures and unfixed, formalin-fixed or alcohol-fixed. Neither the method of storage nor the fixative effected the measured distance between sequential labels in specimens. Fixed bone samples all discoloured with increasing storage. Previous literature alluded to problems with formalin fixation could not be substantiated in this study.

Isotype responses of infected, virus-vaccinated and peptide-vaccinated cattle to foot-and-mouth disease virus

An ELISA to measure bovine serum immunoglobulin isotypes (IgG1, IgG2, IgM and IgA) specific for foot-and-mouth disease virus (FMDV) or for synthetic FMDV peptides is described. Sera from cattle infected by FMDV, vaccinated with conventional inactivated virus vaccines or vaccinated with synthetic peptides were examined using this assay. Generally IgG subclasses dominated the antibody responses of all groups after an early IgM response had waned. An exception to this pattern was seen in the case of a group of immature calves given multiple or high doses of synthetic peptide and in which levels of IgM continued to rise until the end of the experimental period. Both infected animals and those vaccinated with inactivated virus mounted antibody responses in which IgG1 titres tended to predominate over those of IgG2. In some infected animals, an early IgG2 response was evident but resolution of lesions and clinical recovery did not occur until IgG1 antibody appeared in the serum some days later. In synthetic-peptide immunized animals the response was more variable but IgG1:IgG2 ratios at 21 days postvaccination were significantly lower than those of virus-vaccinated animals. It is proposed that differences in the isotype profiles induced by conventional FMD vaccines and those resulting from vaccination of cattle with synthetic FMDV peptides may in part account for the lower protective index of peptide-induced antibodies.

18 NEITHER TESTOSTERONE NOR FSH ARE RESPONSIBLE FOR DECREASED PRODUCTION OP AMH BY BOVINE SERTOLI CELLS IN PRIMARY CULTURE

Production of anti-Müllerian hormone (AMH) by Sertoli cells is maximal during the fetal and neonatal period, and tapers off in the course of postnatal development. To determine the factors responsible for the repression of AMH secretion after birth, Sertoli cells, isolated from immature calves, were plated in an hormonally defined medium and cultured in the presence of 0.1 mM MIX. AMH was assayed in the culture medium using a competition-type RIA capable of detecting 1.5 ng. The proportion of neosynthesized AMH was calculated by determining the amount of immunoreactive AMH unaffected by cycloheximide treatment in conditions where 92 % of protein neosynthesis is inhibited. AMH production by Sertoli cells, expressed per 24 hrs and per 106 cells, fell from 90 ng on the day following plating to 1.5 at day 7. The proportion of AMH synthesized after day 1 was 35 % on day 2 and 88 % on day 3. FSH, 2.5 μg/ml, and testosterone, 2 μM, were added to the culture medium on days 2 and 3, immunoreactive AMH was measured in the culture medium at day 3. Mean daily production of AMH by 106 Sertoli cells was 28.6±2.6 ng in control cultures, 24.6±2.8 in FSH-treated ones and 26.6±3.4 after testosterone treatment. Differences were not significant by analysis of variance. In the same conditions, FSH increased cyclic AMP production approximately tenfold. Further studies are in progress to determine which factors are essential to the continued production of AMH by Sertoli cells in vitro.

Proteoglycans of human infant intervertebral disc. Electron microscopic and biochemical studies.

The ground substance of the intervertebral disc consists primarily of proteoglycans, which give the tissue its stiffness to compression and its resiliency. To investigate the structure and composition of these molecules, we extracted them from human infant nucleus pulposus under associative conditions and from human infant annulus fibrosus and cartilage end-plate under dissociative conditions. We examined the degree of aggregation, the composition, the electron microscopic appearance, and the dimensions of the proteoglycans of the intervertebral disc and compared their structure and dimensions with those of the proteoglycans from bovine hyaline cartilage. Aggregates represented 52 per cent of the proteoglycans of the nucleus pulposus between the ages of one and ten days but only 28 per cent between the ages of six and eight months. Preparations from the corresponding annuli contained 59 per cent aggregates at one to ten days and 47 per cent at six months. The corresponding cartilage end-plate preparations contained 45 and 40 per cent aggregates. The proteoglycans of the annulus fibrosus and cartilage end-plate contained more protein and less hexosamine than did those of the nucleus pulposus. Electron microscopy showed that approximately two-thirds of the aggregates from nucleus pulposus consisted of very short hyaluronate filaments with closely packed monomers. The other third had longer hyaluronate filaments and wider distances between monomers, and closely resembled the aggregates from the annulus fibrosus and cartilage end-plate. Aggregated monomers consisted of two segments: a thin segment connecting directly to the hyaluronic acid filament and a thick segment extending peripherally from the thin segment. The thin segment formed about 12 per cent of the total monomer length in the samples from all three disc tissues. The lower proportion of aggregated monomers, the lower protein content, and the smaller aggregates with closely packed monomers suggest that the nucleus pulposus may contain less link protein than do the annulus fibrosus and cartilage end-plate. Compared with proteoglycan aggregates from bovine hyaline cartilage, proteoglycan aggregates from human intervertebral disc were shorter and had fewer monomers and wider spacing between monomers. The aggregated monomers from the three components of the intervertebral disc had an average length of 209 +/- 90 nanometers, compared with 210 +/- 114 nanometers for monomers from hyaline cartilage of skeletally mature cows, 250 +/- 116 nanometers for monomers from hyaline cartilage of skeletally immature calves, and 288 +/- 108 nanometers for monomers from fetal animals.(ABSTRACT TRUNCATED AT 400 WORDS)

Metabolism of nalidixic acid in the calf: the effect of age

The metabolism of nalidixic acid (NA) has been studied in Holstein calves following the administration of a single dose of the 14C-labeled sodium salt, or of multiple doses of the unlabeled salt. In immature calves (30–45 kg) the disposition of the drug proved to be very slow (a half-life of about 24 hours) as compared to the only existing norm (a half-life of 1–1.5 hours in adult humans). The label derived from a single 2.3-g dose of the 14C-labeled sodium salt, for example, was not completely cleared from the tissues and excreta within 15 days. The plasma and urine of calves receiving 0.25-g doses of sodium NA twice daily for 4 days appeared to be drug free within 48 hours after the last dose, but those receiving 1.25-g doses twice daily for the same period were still excreting traces of the drug 6 days after the last dose. On the basis of tissue analyses, 30–45-kg calves receiving 0.25-g doses of the sodium salt twice daily for 5 days were essentially, but not completely, drug free 4 days after the administration of the last dose. The metabolic pattern of NA in these immature calves differed from that in man in the high level of fecal excretion, the comparatively low extent of conjugation of the drug excreted in the urine, and in the failure (or inability) to excrete the free drug in the urine in a concentration much exceeding that in the plasma. At 7 months of age the metabolic pattern of NA in the calf was quite different. The plasma half-life was now about 1.5 hours, the animals excreted the free drug in the urine in a concentration at least 10–15 times that in the plasma, and the extent of conjugation for equivalent doses per kilogram was slightly increased (from 37%–50%). The incomplete development of metabolic and excretory mechanisms is considered, therefore, to account for the slow disposition of NA in the immature calf.