Oocyte quality and viability in Nguni and Hereford cows exposed to different levels of dietary protein.

High blood urea nitrogen (BUN) concentration decreases fertility in ruminants. Nguni cattle are reported to maintain BUN concentration more efficiently than other beef breeds. Our objectives were to determine if BUN concentration differed between Nguni and Hereford cows exposed to a high protein ration, and if breed or BUN and serum protein concentrations at the time of oocyte pick-up affected oocyte quantity, quality, and viability. Twelve Nguni and 10 Hereford cows were randomized into high or normal BUN-inducing diets in a crossover design. Ultrasound-guided oocyte pick-up was performed twice weekly; oocytes were counted, visually graded and the viable oocytes were pooled by treatment and breed for in vitro maturation, fertilization, and culture. Nguni cows on the highest protein ration achieved lower mean BUN concentration than Herefords (P < 0.05), and Nguni cows reached BUN concentrations above 20 mg/dL less frequently than Herefords (P = 0.03). Donor BUN concentration above 20 mg/dL at the time of oocyte pick-up, but not breed, independently decreased the number of good quality oocytes harvested. Increasing weighted mean serum albumin of donor cows was independently associated with the number of oocytes that cleaved by day 2 and that reached morula stage by day 7 (P = 0.01). In conclusion, Nguni cows reached the critical threshold of 20 mg/dL BUN less frequently than Herefords; BUN of donor cows above 20 mg/dL negatively affected visual oocyte quality independent of breed, and increasing serum albumin of donor cows improved viability of bovine oocytes.

The potential effects and interactions of oxidative stress and trace minerals on fresh and frozen semen in bulls - a review.

Reproduction is one of the most important factors determining successful cattle farming systems. Management practices, such as nutritional supplementation, can influence the reproductive performance of cattle. The objective of this literature review is to determine the potential value of injectable trace mineral administration on fresh and cryopreserved semen quality of bulls. A search of keywords related to the topic was performed on published articles and textbooks. The search was narrowed to the 40 most relevant references. Several studies have demonstrated a positive association between trace mineral supplementation and bull semen quality. Moderate amounts of reactive oxygen species (ROS) play an important role in normal spermatogenesis, but oxidative stress (OS), as experienced with adverse environmental conditions or disease, can contribute to idiopathic male infertility by negatively impacting spermatogenesis. Trace minerals such as selenium, copper, zinc, and manganese have been demonstrated to have antioxidant effects in mammals. Due to the complexity of oral ingested trace mineral bioavailability, injectable trace mineral supplementation prior to physiological periods with known deficiencies or increased requirement can benefit the animal. The potential benefits of injectable trace mineral supplementation to minimise oxidative damage to spermatogenesis in breeding bulls need further investigation. Positive results from such studies can lead to the implementation of injectable trace mineral supplementation strategies prior to the breeding season to minimise the detrimental effects of OS and can improve semen quality.

Retention time of digesta in the rumen: its repeatability and relationship with wool production of Merino rams.

The purpose of this experiment was to determine whether differences in retention time (RT) of digesta in the rumen are associated with individual differences in wool growth rate between Merino rams. Fifty-eight rams were offered a pelleted diet at ad libitum and restricted levels. Digesta RT in the rumen was estimated from fecal excretion plots using 51Cr-mordanted feed as a marker. Wool growth rate during feeding for ad libitum intake was linearly correlated to DMI (r = .37; P < .01) and RT (r = -.32; P < .01). Multiple logistic regression analysis, used to overcome multicollinearity, showed that RT per se exerted a greater effect (P < .07) than DMI (P < .34) on wool growth rate at ad libitum feed intake. When data were blocked by wool growth rate keeping mean BW constant over all groups, high wool producers had shorter (P < .01) RT than low wool producers. Using the probability values of the multiple logistic regression analysis (CATMOD), the probability of obtaining a low wool growth rate with long RT was estimated to be .73, whereas that of obtaining a low wool growth rate with short RT approximated zero, in the ad libitum period. During the restricted feeding period, the probability of obtaining a low wool growth rate with long RT was estimated to be .46, whereas that of obtaining a low wool growth rate with short RT was estimated to be .17. Repeatability, the upper limit of heritability, was .45 (P < .01) and .6 (P < .01), using regression correlation and Spearman rank correlation coefficients, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Characteristics and efficiency of fast-growing feedlot steers fed different dietary energy concentrations.

Most prediction equations of feedlot performance cover average daily gains (ADG) below 1.5 kg/d. The question is whether these equations would be accurate for higher ADG. Medium-to-large-framed weanling and yearling steer calves were fed individually using a transponder-electronic gate system in three feedlot trials and fed in groups in two trials. Average daily gain ranged from .9 to 2.1 kg. Steers were implanted, fed to the same degree of finish, and slaughtered to obtain dressing percentage and cold carcass weight. Initial carcass weights were estimated from initial slaughter groups. Dietary ME concentration (i.e., 10.5, 11.5, 12.0, and 12.5 MJ ME/kg of DM, where 1 Mcal = 4.184 MJ), initial weight, dry matter intake (DMI), and days fed could explain 57% of the variation in ADG. The partial contribution of DMI to the total variation was only 5.2%, confirming the low correlation between DMI and ADG in feedlot trials. The correlation between metabolizable energy intake (MEI) and MEI/ADG also was low, but 80% of the variation in MEI/ADG was accounted for by the variation in ADG. Intake patterns, regardless of dietary energy concentration, indicate that ADG increased with DMI only when ADG was below 1.5 kg/d. Therefore, current prediction equations apparently overpredict ME requirements for fast-growing feedlot steers. Optimal performance occurred at a ME concentration of 12.0 MJ/kg of DM rather than 12.5 MJ/kg of DM. Dressing percentage and carcass gain increased as dietary energy concentration and ADG increased, and current prediction equations should predict that of fast-growing feedlot steers equally well.

Blood metabolite and regulatory hormone concentrations and response to metabolic challenges during the infusion of mimosine and 2,3-dihydroxypyridine in alpine goats.

Sixteen Alpine wethers (average BW 35 +/- 2 kg) were used to evaluate the effect of continuous 48-h intravenous infusions of saline (CON), mimosine (MIM; 200 mg.kg.75.d-1), 2-hydroxy-3(1H)-pyridine (2,3-DHP; 200 mg.kg.75.d-1, or MIM+2,3-DHP (100 mg of MIM plus 100 mg of 2,3-DHP-kg.75.d-1) on hepatic function and selected blood metabolite and circulating hormone concentrations. Neither MIM nor 2,3-DHP affected plasma ammonia N, glucose, cortisol, or insulin concentrations over time (P > .10). Jugular plasma total protein concentration was greater in the MIM group (P < .07). Plasma triiodothyronine (P < .01) and thyroxine (P < .08) concentrations were higher in the goats receiving the MIM, 2,3-DHP, and MIM+2,3-DHP infusions than in the goats receiving the CON infusion. Plasma urea N concentration was decreased by MIM (P < .10) and MIM+2,3-DHP (P < .03) compared with the CON infusion. A Propionate Load Test was conducted at 24 to 28 h into the infusion to assess the toxins' effects on the liver's ability to increase circulating glucose concentrations in the presence of elevated propionate levels. The results indicated that neither 2,3-DHP nor MIM reduced the liver's ability to respond to a bolus dose of propionate (P > .10). Following a Urea Load Test, circulating ammonia N and glucose concentrations in the MIM, 2,3-DHP, and MIM+2,3-DHP treatments had lower peak values than that in the CON treatment (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

The venous drainage of the cervical vertebrae of the ox (Bos taurus L.).

The venous drainage of the cervical vertebrae of the ox was studied in 16 animals (Friesland, Jersey and Guernsey cross-breeds), ranging from near full-term foetuses to adults. The extra- and intraosseous veins of the cervical vertebrae are described and illustrated. The nutrient vessels are derived from the vertebral, deep cervical, occipital and internal jugular veins. In addition to the dorsal and ventral external venous plexuses, a lateral external venous plexus is described. The intraosseous veins correspond in the main to the arteries. They are described and illustrated with reference to the available literature. In both young and adult animals anastomoses between epi- and metaphysial vessels are reported. The role of the internal ventral vertebral venous system as a collateral pathway is stressed and comments are made on its possible functional role.

The arterial blood supply of the cervical vertebrae of the ox (bos taurus l.).

The arterial supply to the cervical vertebrae of the ox was studied in 22 animals (Friesland, Jersey and Guernsey cross-breeds), ranging from near full-term foetuses to adults. Various techniques, including angiography and clearing of bone, were employed to expose the extra- and intraosseous distribution of the arteries and a description is given of a modified Spalteholtz clearing technique. The extraosseous nutrient arteries are described and illustrated. A uniform pattern emerged from the investigation and it is suggested that the main branches be named: (1) the artery of the vertebral arch; (b) the artery of the transverse process; (c) the basivertebral arteries. Frequent anastomoses between epi- and metaphysial vessels in young animals are reported, and stress is laid on the effective collateral supply maintained by the extra- and intraosseous nutrient vessels.

Osteology of the thoracic limb of the African elephant (Loxodonta africana).

The forelimb bones of 8 elephants (7 adults, 1 juvenile) were studied. In addition, the bones of the digits were dissected and studied in situ in a mature specimen. The scapula, humerus and bones of the antebrachium (particularly the ulna) are massive in comparison to the short, relatively small bones of the manus. There are 8 carpal bones, 5 metacarpal bones and 5 digits. Digits 2-4 consist of 3 phalanges each. The 5th digit consists of 2 phalanges, while the 1st is represented by a single phalanx which is tusk-like and pointed. The distal phalanges of digits 2-4 are very small and do not articulate with the middle phalanges. The proximal sesamoids are well developed and are present on the palmar aspect of all 5 metacarpophalangeal joints. All the bones are illustrated from at least 2 aspects.

Osteology of the pelvic limb of the African elephant (Loxodonta africana).

The pelvic girdle was characterized by large, transversely-placed ilial wings. The femur was the longest bone of the skeleton and its fovea capitis was situated caudomedially between the epiphyseal line and the articular surface of the femoral head. A wedge-shaped patella articulated with the femoral trochlea. The bones of the crus were approximately half as long as the femur and consisted of the sturdy tibia and slender fibula. The condyles of the tibia were concave and the femoro-tibial joint was congruent with rudimentary menisci. The tarsus consisted of seven bones which were arranged in three rows. There were five metatarsal bones. Only four digits were present, the third and fourth consisted of three phalanges each while the second and fourth digits were smaller and consisted of two phalanges each. The first digit was represented by one proximal sesamoid bone only. A large, cartilagenous rod or prehallux was attached to the first tarsal and metatarsal bones. Proximal sesamoid bones were present on the plantar aspect of the trochleae of metatarsal bones 1-V. The pes was found to be digitigrade and the digits rested on a thick pad of elastic connective tissue and fat.

Recurrent pneumothorax associated with a pulmonary emphysematous bulla in a dog: surgical correction and proposed pathogenesis.

A three year old dog was affected with recurrent dyspnea for two months, due to a recurrent pneumothorax. This followed an episode of mild blunt trauma to the thorax and transient strangulation. Conservative therapy of aspiration of air by repeated thoracentesis gave only temporary relief. Thoracic radiographs indicated the presence of a bulla in the right middle lung lobe. An exploratory thoracotomy confirmed the diagnosis, and a lobectomy was successfully performed. The pathogenesis of acquired pulmonary bullae is postulated. Reasons for the predisposition of the right middle lung lobe are outlined. These are related to the anatomy of the right middle bronchus, and include its position between the right pulmonary artery and vein, its oval shape, and the absence of cartilagenous support at its origin.

The impact of backboard size and orientation on sternum-to-spine compression depth and compression stiffness in a manikin study of CPR using two mattress types.

OBJECTIVES: To explore how backboard orientation and size impact chest compressions during cardiopulmonary resuscitation (CPR). METHODS: Experiments were conducted on a full-body CPR training manikin using a custom-built simulator. Two backboards of different sizes were tested in longitudinal (head to toe) and latitudinal (side to side) directions to assess the impact of size and orientation on chest compressions during CPR. The net sternum-to-spine displacement, combined mattress and sternal displacement as well as the axial reaction force were measured during each test. RESULTS: The difference in net compression depth between the larger and smaller backboards ranged between 0.08±0.30 cm and 1.47±0.13 cm, while the difference in back support stiffness varied between 103.7±211 N/cm and 688.1±180.3 N/cm. The difference in net compression depth between the longitudinal and latitudinal backboard orientations ranged from 0.07±0.32 cm to 0.34±0.18 cm, while for the back support stiffness the difference was between 13.4±50.0 N/cm and 592.2±211.0 N/cm. CONCLUSIONS: The effect of backboard size on chest compression (CC) performance during CPR was found to be significant with the larger backboard producing deeper chest compressions and higher back support stiffness than the smaller backboard. The impact of backboard orientation was found to depend on the size of the backboard and type of mattress used. Clinicians should be aware that although a smaller backboard may be easier for rescuers to manipulate, it does not provide as effective back support or produce as deep chest compressions as a larger backboard.

Long-chain polyunsaturated fatty acids protect the heart against ischemia/reperfusion-induced injury via a MAPK dependent pathway.

The mechanisms by which long-chain dietary polyunsaturated fatty acids (PUFAs) protect against cardiovascular disease are largely unknown. The present study determines the effects of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) on the response of neonatal rat cardiomyocytes to simulated ischaemia (SI) and reperfusion (R). Myocytes isolated from 1-2 day old Wistar rat hearts were cultured with or without EPA or ARA and exposed to 1 h SI followed by 30 minutes reperfusion. Apoptosis was evaluated by caspase-3 activation, poly-(ADP-ribose) polymerase (PARP) cleavage and nuclear condensation. EPA (20microM) and ARA (20microM) significantly inhibited caspase-3 activation and PARP-cleavage and reduced the apoptotic index during reperfusion. Both fatty acids significantly increased ERK phosphorylation and decreased p38 phosphorylation during reperfusion. The mechanism of action of ARA on the MAPKs was further investigated with okadaic acid (to inhibit serine-threonine phosphatases) and orthovanadate (to inhibit tyrosine phosphatases). Vanadate, but not okadaic acid, significantly reduced ARA-induced inhibition of p38 phosphorylation, suggesting the involvement a tyrosine phosphatase during SI/R. Mitogen-activated protein kinase phosphatase-1 (MKP-1), a dual-specificity phosphatase, was targeted and a significant induction of MKP-1 by ARA and EPA was observed. It was demonstrated for the first time that EPA and ARA protect neonatal cardiac myocytes from ischaemia/reperfusion-induced apoptosis through activation of ERK as well as induction of a dual-specific phosphatase, causing dephosphorylation of the pro-apoptotic kinase, p38. The cardioprotective effects of EPA and ARA could also be demonstrated on the functional recovery of isolated perfused hearts subjected to global ischemia.

Concanavalin A binding to the epithelial surface of the developing mouse olfactory placode.

Concanavalin A (Con A), a lectin binding to mannosyl and glucosyl residues of glycoproteins and glycolipids, was used to study the appearance of carbohydrate-rich cell surface material on the olfactory placode and nasal processes which contribute to formidine was also used in an attempt to correlate changes in labeling index with formation of the olfactory placode and nasal processes. The cell surface of the early frontonasal epithelium binds Con A very little, if at all, but Con A binding was observed when the olfactory placode could be identified as a plate of cuboidal cells that exhibited a reduced labeling index. During the period of formation of the nasal processes, Con A binding was observed on the facial epithelium including the presumptive contact region. There was also a decline in the labeling index throughout primary palate formation. This study provides three criteria by which the olfactory placode can be identified: a morphological change of placode cells to a cuboidal shape, a synthesis or rearrangement of surface coat material that binds Con A, and a reduced labeling index.

Rapid nasal pit formation in mouse embryos stimulated by ATP-containing medium.

The primary palate in the mouse is composed of epithelium and mesenchyme. Most studies on primary palate formation have concentrated on the role of the mesenchyme based upon the hypothesis that mesenchymal accumulation elevated the sides of the nasal placodes, thereby creating the depressed nasal pits. This study demonstrates that the epithelium is actively participating in formation of the nasal pits. Mouse heads from embryos of 14 to 24 paris of body somites were placed in medium 199 and photographed. The medium was replaced with medium containing 1.0 mM ATP and 0.05% Triton-X. Within 5 minutes, the placodes either thickened or invaginated. Control heads exposed to medium 199 containing only Triton-X or ATP did not show any invaginations. The rapid thickening and invagination stimulated by ATP-containing medium demonstrates that the epithelium is the dominant tissue in nasal put formation. Although mesenchymal accumulation certainly contributes to the formation of the primary palate, it is the placodal epithelial invagination that appears to shape the nasal pits.

Patterns of cellular proliferation during thyroid organogenesis.

The changes in rate and location of cellular proliferation were analyzed to determine if localized areas of cell division were influencing shape changes in the chick thyroid. Pulse labeling with tritiated thymidine indicates that the gland's labeling index declines throughout its development. Initially, the thyroid placode has a lower labeling index than the neighboring pharyngeal epithelium. An evaluation of the positions of pulse-labeled cells reveals that the evaginating thyroid grows by annexing cells from the pharyngeal epithelium. The older evaginated regions of the gland exhibit the lowest labeling indices. The newly acquired regions still maintain higher labeling indices.