Effects of growth hormone and feeding level on endocrine measurements,hormone receptors,muscle growth and performance of prepubertal heifers

Prepubertal Friesian heifer calves (n = 24, initial BW = 195 +/- 5 kg) were assigned to a 2 x 2 factorial block design and used to evaluate the effects of daily GH treatment (0 or 15 mg/d) at either a low or a high feeding level in a 5-wk treatment period on endocrine measurements, hormone receptors, muscle growth, and overall performance. In the pretreatment period, a low feeding level was employed for all calves. During the treatment period, animals at the low feeding level had free access to a roughage-based mixture, whereas animals at the high feeding level had free access to a concentrate mixture and were offered 2 kg/d of the roughage-based mixture. Blood samples were collected weekly starting 3 wk before treatment. Longissimus (LM) and supraspinatus (SS) muscles were obtained at slaughter. Metabolizable energy intake was 81% higher, digestible CP intake was 140% higher, and ADG was 115% higher (all P < 0.001) at the high vs. low feeding level. Feed (DMI, ME, and protein) intake was not affected by GH treatment, but ADG was 18% higher (P < 0.13) in GH-treated than in control heifers at both feeding levels. Although of different magnitudes, the muscle anabolic effects of GH treatment and high vs. low feeding level were additive, and both treatments increased carcass weights (P < 0.02 and P < 0.001, respectively), LM (P < 0.05 and P < 0.001), and SS (P < 0.06 and P < 0.003). The anabolic effect of GH treatment was similar in both muscles, whereas the effect of feeding level was most pronounced in LM. Overall, GH treatment increased plasma GH, IGF-I (both P < 0.001), and IGFBP-3 (P < 0.02); however, GH treatment increased total IGF-I, free IGF-I, and IGFBP-3, and decreased IGFBP-2 mainly at the high feeding level (GH x feeding level interaction; P < 0.02, 0.01, 0.03, and 0.10, respectively). The high feeding level increased insulin, free and total IGF-I, and IGFBP-3 (all P < 0.001), but decreased GH and IGFBP-2 (both P < 0.001). High feeding increased type-1 IGF receptor density (P < 0.02), mainly in LM, in accordance with the largest anabolic response in this muscle, whereas GH treatment had no effect on type-1 IGF receptors. The results suggest that in skeletal muscle, the anabolic effects of exogenous GH are related to endocrine changes in the GH-IGF axis, whereas the effects of feeding level also seem to rely on IGF receptor density in the muscles.     

Somatomedins

Somatomedin is the name for the hormone or hormones that mediate the effects of growth hormone. The suggestion of this term in 1972 represented establishment of a new theory concerning growth hormone action and growth regulation. The development and present status of the theory is reviewed. A discussion of factors affecting somatomedin level in serum leads to conclusions regarding practical use of somatomedin determinations. Levels of somatomedin can only be determined by bioassay because somatomedin is not chemically identified. The need for international coordination of the work on somatomedin is emphasized.

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Kurzfassung Somatomedin ist die Bezeichnung für das Hormon bzw. die Hormone die die Wirkung des Wachstumshormons überführen. Der Vorschlag dieser Bezeichnung von 1972 repräsentierte die Aufstellung einer neuen Theorie betreffs Wachstumshormonwirkung und Wachsregulierung. Die Entwicklung sowie der augenblickliche Stand der Theorie ist besprochen worden. Die Diskussion über die Faktoren die auf dem Somatomedinniveau im Serum einwirken, führten Konklusionen betreffs der praktischen Anwendung der Somatomedinbestimmung mit sich. Das Somatomedinniveau kann nur durch biologische Methoden bestimmt werden weil die chemische Natur des Somatomedin noch nicht identifiziert ist. Der Bedarf internationaler Koordination über Arbeiten von Somatomedin ist nachdrücklich betont.Riassunto Somatomedina è la denominazione di un ormone o degli ormoni intermediari dell'ormone della crescita. Questa recente definizione (1972) costituisce una nuova teoria sull'azione degli ormoni della crescita e della regolazione stessa della crescita. L'autore fa il punto sullo sviluppo e sullo stato attuale di questa teoria. La discussione dei fattori che influiscono sul tasso delle somatomedine nel siero sanguigno, porta a indicazione sull' utilizzazione pratica del loro dosaggio che deve essere effettuato con un metodo biologico, visto che la composizione chimica di questo ormone non è nota. Si sottolinea la necessità di una coordinazione sul piano internazionale dei lavori sulle somatomedine.

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Resume La somatomédine est la dénomination d'une hormone ou des hormones médiatrices des hormones de la croissance. Cette appellation récente (1972) ne constitue en fait qu'une nouvelle théorie de l'action des hormones de la croissance et de la régulation même de la croissance. L'auteur résume l'évolution de cette théorie jusqu'à ce jour. En discutant des conditions qui influent sur le taux de somatomédine dans le sérum sanguin, il donne des indications sur l'utilisation pratique du dosage qui ne peut être effectué que par une méthode biologique, la composition chimique de cette hormone n'étant pas encore complètement connue. L'intérêt d'une coordination des travaux sur le plan international est souligné.

     

Reticulosis of the visual system in a dog

A 7-year-old male Kerry Blue Terrier had been compensating for a visual deficit for approximately 2 months. Five days before examination, the dog had suddenly lost all vision and the pupils had become widely dilated and unresponsive to light. Ophthalmic examination revealed inflammation of the optic discs. Response to therapy was favourable but temporary.
Post mortem findings consisted of granulomatous optic neuritis, meningoencephalitis and chorioretinitis, similar to reticulosis.     

Effect of oat decortication on chemical composition,in vitro digestibility and in situ degradability

The effect of decortication on chemical composition and degradability characteristics of four Danish oat varieties was investigated. Effective degradability (ED) and post-ruminal disappearance (PRD) were measured by in situ and mobile bag techniques respectively. Decorticated oat showed higher (p = .01) concentrations of crude protein (CP; 134 vs. 108 g/kg DM) and crude fat (71.6 vs. 53.1 g/kg DM) and a higher (p = .001) organic matter digestibility (OMD; 888 vs. 703 g/kg OM) than oat. The content of total fatty acids (FA) in DM was higher in decorticated oat. The proportion of linoleic acid (C18:2 n6) increased (p < .05) due to decortication, while the linolenic acid (C18:3 n3) proportion of total FA decreased in decorticated oat. Decortication increased (p = .01) the concentration of amino acids (AA), but the proportion of lysine in total AA decreased (p < .002). Effective degradability (ED) of both DM and CP was (p < .001) higher in decorticated oat. Decortication increased the total tract disappearance (TTD) and PRD of CP (p < .001). In conclusion, decortication can be used as a practical approach to increase the nutritional value of oat.     

Ocular manifestation of systemic histiocytosis in a dog.

A 3-year-old sexually intact female Bernese Mountain Dog was referred for treatment of a descemetocele of the left eye. Physical examination revealed bilateral exophthalmos and scleral thickening, multiple cutaneous nodules, and mandibular paralysis in addition to ulcerative keratitis associated with a Pseudomonas infection. One year prior to examination, a biopsy specimen of the episcleral tissue from the right eye had been interpreted as nodular granulomatous episclerokeratitis (fibrous histiocytoma). Immunosuppressive treatment prior to referral had not resulted in remission of the ocular lesions. When we examined the biopsy specimen, we interpreted the lesions to represent episcleral involvement of systemic histiocytosis. Because of the poor prognosis, the dog was euthanatized.     

Effects of toasting blue lupins, soybeans or barley as supplement for high-yielding, organic dairy cows fed grass-clover silage ad libitum

The effect of toasted supplement on milk production was examined in three experiments on an organic study farm during the winter 2004/2005. Three types of iso-energetic supplement feed, toasted or untreated, were examined in each experiment, with an untreated cereal mixture as control. The supplement under investigation was: lupins in experiment 1, barley in experiment 2 and soybeans in experiment 3. The same forage mixture of grass-clover silage (84% of DM), grass pellets (11% of DM) and straw (5% of DM) was fed ad libitum in all the experiments.

Toasting decreased effective rumen protein degradability determined in situ for all three supplements. Compared to untreated lupins toasting of lupins tended (P = 0.10) to increase milk yield, whereas toasting of soybeans did not affect milk yield. Toasting of lupins decreased (P = 0.03) milk protein content (32.2 versus 32.7 g/kg), whereas toasting of soybeans did not affect milk protein content. ECM yield was significantly higher (P = 0.002) for cows fed toasted soybeans than for cows fed untreated soybeans (28.1 versus 26.4 kg ECM) whereas there was no significant effect on ECM yield from toasting lupins or barley. It can be concluded that the potential of toasting to increase the supply of metabolisable protein under organic feeding conditions is variable between feeds.     

Allocation of feed based on individual dairy cow live weight changes: II: Effect on milk production

Based on individual cow live weight gain, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems, and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH), and 93 Danish Jersey (DJ). The objective of the present paper was to examine the milk yield obtained in response to three feeding strategies. The interrelationship between feed intake and live weight changes is presented in a companion paper.Cows were stalled in a loose-housing system based on automatic milking, automatic recording of feed intake and automatic weighing of the cows. All cows had 3 kg of individually separately offered concentrate (ISC) in addition to a mixed ration (MR). Cows were either allowed a medium energy MR during whole lactation (strategy MR1) or a high energy MR during early lactation, which was reduced to a low energy MR either early or late (strategy MR2-E and MR2-L). The early and late changes were defined as a live weight gain after live weight minimum at 15 and 35 kg, respectively, for DR/DH and 11 and 25 kg, respectively, for DJ. When MR energy concentration was changed, cows on the MR2 strategies were offered 3 kg per day of extra concentrate. The total allowance of 6 kg ISC was stepwise reduced to 3 kg per day as live weight continued to increase until 50 and 35 kg for DR/DH and DJ, respectively.Compared to feeding the MR1 strategy, the analysis showed that feeding the MR2 strategies did not significantly affect milk yield within primiparous DR and DH or within any DJ, as total lactation feed energy intake within these groups of cows was not significantly affected by the feeding strategy. Results obtained for multiparous DH showed that it is possible to increase milk yield without reducing the milk:feed ratio, when MR2 strategies were applied compared to the MR1 strategy. Feeding high energy rations during early lactation caused a higher peak feed energy intake within multiparous cows of DH and DR, but only multiparous DH obtained higher peak ECM yield in response to higher feed energy intake in early lactation. Across breed the results suggested that cows offered the MR2-E strategy might obtain higher lactation ECM yield compared to cows offered the MR2-L strategy due to a higher ECM yield persistency obtained by cows offered the MR2-E strategy. Results on feed intake and live weight changes presented in a companion paper indicated, that cows offered the MR2 strategies obtained a lower extent of mobilization compared to cows offered the MR1 strategy, and feeding the MR2-E strategy significantly increased duration of the mobilization period, which might have increased MR2-E cows' ability to maintain a high milk production during mid lactation.     

Dietary-induced changes of muscle growth rate in pigs: effects on in vivo and postmortem muscle proteolysis and meat quality

The effects of various growth rates in pigs induced by four different feeding strategies on the activity of the calpain system and on postmortem (PM) muscle proteolysis and tenderness development were studied. An increased growth rate may be caused by an increased protein turnover, which results in up-regulated levels of proteolytic enzymes in vivo that, in turn, possibly will affect PM tenderness development. It can be hypothesized that increased proteolytic activity pre-slaughter will increase the PM tenderization rate. From postnatal d 28 to d 90 (phase 1) the pigs were divided into two groups, given either ad libitum (A) or restricted (R, 60% of ad libitum) access to feed. The two groups were then divided into two subgroups, given either restricted or ad libitum access to feed from d 91 to slaughter at d 165 (phase 2). Measurements of the activity of mu-calpain, m-calpain, and calpastatin; concentrations of total collagen and the percent of soluble collagen; and RNA, DNA, and elongation factor-2 where made at slaugther. Myofibrillar fragmentation index (MFI) was determined at slaughter and 24 h PM. Warner-Braztler shear force was determined 1 d and 4 d PM. Pigs fed restricted diets in phase 1 and fed ad libitum in phase 2 (RA pigs) had increased growth rates in the last phase compared to pigs fed ad libitum during both phase 1 and phase 2 (AA pigs). The increased growth rate (compensatory growth) was followed by an increased proteolytic potential (mu-calpain:calpastatin ratio), increased MFI values, and higher tenderization rates. There was a positive correlation between the activities of m-calpain and growth rates (r = 0.35, P = 0.03), and between RNA levels and growth rates (r = 0.43, P = 0.006). The proposed hypothesis is largely supported by the results. The activities of both mu- and m-calpain at slaughter were highest in fast-growing pigs. The calpain activity was highest in RA pigs, which in turn also had the fastest growth rates prior tslaughter among the four groups. This implies that the synthesis of these enzymes was up-regulated during the second feeding period to a larger extent in RA pigs. The proteolytic potential and the MFI values indicate that the up-regulated in vivo calpain activity had an effect on PM protein degradation, which also is supported by the higher tenderization rate in RA pigs.     

Management of a persistent corneal erosion in a boxer dog

A dog was presented to the New York State College of Veterinary Medicine with a one-month history of corneal ulceration. The corneal lesion was diagnosed as a persistent corneal erosion (PCE) and treated initially with debridement and supported with a contact lens. One week later, the corneal erosion remained unepithelialized. Following debridement, multiple anterior stromal punctures were performed. Within 10 days, the erosion was healed as evidenced by coverage of the cornea with adherent, uninterrupted epithelium. The proposed etiology and management of PCE in dogs is discussed.