The effect of restricted feeding on growth hormone (GH) secretory patterns in genetically lean and fat wether lambs

2000 ◽  
Vol 70 (3) ◽  
pp. 425-433 ◽  
Author(s):  
S. M. Francis ◽  
R. P. Littlejohn ◽  
S. K. Stuart ◽  
B. A. Veenvliet ◽  
J. M. Suttie
Keyword(s):  
Growth Hormone ◽  
Treatment Group ◽  
Developmental Change ◽  
Plasma Concentrations ◽  
Live Weight ◽  
Carcass Composition ◽  
Restricted Feeding ◽  
Ad Libitum ◽  
Plasma Gh ◽  
And Control

AbstractThe aim of this work was to determine whether developmental changes in growth hormone (GH) secretory patterns and carcass composition were influenced by nutrition and genotype in sheep. Four-month-old wether lambs from lean (low backfat), fat (high backfat) and control selection lines were nutritionally restricted to maintain a 28 kg live weight or given food ad libitum for 24 weeks. Plasma concentrations of GH and insulin-like growth factor 1 (IGF-1) were measured at predetermined times and carcass composition of the animals determined at the end of the trial.From week 3 on, restrictions in dry matter (DM) intake were observed as the ad libitum treatment group had a significantly greater intake than the restricted treatment group (7·70 v. 5·80 kg DM per week, s.e.d. = 0·81). Differences in live weight between the feeding treatments were significant (P < 0·05) at week 9. The restricted feeding regime was associated with significant reductions in plasma levels of IGF-1 but had no effect (P > 0·05) on carcass weight-adjusted carcass fat proportion at the close of the trial. The effect of food restriction on GH secretory patterns was variable. Although there was initially a suppression in mean plasma GH, there was subsequently significantly higher mean plasma GH in the restricted feeding treatment. Periodogram analysis indicated that both the absolute levels of GH and the GH secretory pattern were altered by restricted feeding. In all animals, mean and basal GH concentrations, as well as the frequency and amplitude of pulses, declined from February to March and then increased from May to July (P < 0·001).DM intake and live weight did not differ (P > 0·05) between genotypes, however the fat genotype had greater carcass fatness than lean or control genotypes (P < 0·01). There were no consistent differences between genotypes in plasma IGF-1 concentrations. In the ad libitum treatment, the lean and control genotypes had higher plasma GH levels than the f at genotype but the pattern of GH release did not vary. Under restricted feeding, both the pattern and the level of plasma GH varied between genotypes.It is concluded that the developmental change in GH secretory patterns is affected by nutrition but not in a consistent manner. Although restricted feeding resulted in higher mean plasma GH concentrations later in the trial, this did not result in a change in carcass composition. The biological cues which lead to increased fat deposition in older lambs need further study but plasma GH levels may not he an important mechanism in this process.

Pre-pubertal mammogenesis in the sheep 3. The effects of restricted feeding or daily administration of bovine growth hormone and bromocriptine on mammary growth and morphology

1986 ◽  
Vol 42 (1) ◽  
pp. 53-63 ◽  
Author(s):  
I. D. Johnsson ◽  
I. C. Hart ◽  
A. Turvey
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Live Weight ◽  
Restricted Feeding ◽  
Fat Pad ◽  
Live Weight Gain ◽  
Parenchymal Tissue ◽  
Mammary Fat Pad ◽  
Ad Libitum ◽  
Plasma Gh

ABSTRACTIn crossbred female lambs reared on a concentrate diet between 8 and 20 weeks of age, a restriction in food intake to 40 g/kg body weight per day decreased live-weight gain (155 g/day) compared with that in control lambs fed ad libitum (284 g/day) and significantly reduced final live weight and the size of the mammary fat pad (P < 0·001). However, restricted lambs at 20 weeks had more total parenchymal deoxyribonucleic acid (DNA; 54·7 v. 47·5 mg) occupying a greater mass of mammary fat pad (17·0 v. 13·2 g) than control lambs (P > 0·10). Restricted feeding had little effect on mean plasma growth hormone (GH) concentrations at 12 and 18 weeks of age, but decreased plasma insulin and prolactin concentrations.In lambs fed ad libitum, daily subcutaneous (s.c.) injections of 0·1 mg bovine pituitary GH per kg live weight between 8 and 20 weeks of age significantly increased daily live-weight gain (347 g/day; P < 0·001) and also increased total mammary parenchymal DNA (71·2 mg; P < 0·10) and the mass of fat pad occupied by parenchymal tissue (20·6 g; P < 0·05), compared with the control treatment. Daily s.c. injection of bromocriptine (1 mg/day) had no effect on either body or mammary growth, but tended to reduce the effects of bovine GH when given in combination. Secretory activity was observed in the parenchymal tissue of the eight lambs receiving bovine GH alone, and also in five control lambs and three lambs receiving bromocriptine alone. Three lambs that had attained puberty by 20 weeks of age had the poorest mammary development of their respective treatment groups.Mammary gland development at 20 weeks of age was significantly correlated across treatment means with plasma GH concentrations estimated at 18 weeks of age (r = 0·95; P < 0·05), but no correlations of similar magnitude were found between individuals within treatments at 20 weeks. Strongest correlations were found among 8-week-old lambs, where mammary parenchymal DNA was positively correlated with mean plasma GH (r = 0·62) and the GH:insulin ratio (r = 0·79) and negatively correlated with the prolactin:GH ratio (r = -0·65).

Bovine growth hormone in lambs: effects on carcass composition and tissue distribution in crossbred females

1987 ◽  
Vol 44 (1) ◽  
pp. 117-124 ◽  
Author(s):  
B. W. Butler-Hogg ◽  
I. D. Johnsson
Keyword(s):  
Growth Hormone ◽  
Tissue Distribution ◽  
Subcutaneous Injection ◽  
Subcutaneous Fat ◽  
Live Weight ◽  
Carcass Composition ◽  
Carcass Quality ◽  
Pituitary Growth Hormone ◽  
Longissimus Lumborum ◽  
Ad Libitum

ABSTRACTThirty-two Dorset Down × Finn Dorset female lambs were reared from 8 to 20 weeks on an ad libitum concentrate diet. They comprised four groups of eight lambs, one on each of the following treatments: (1) control, no injections; (2) daily subcutaneous injection of 0-1 mg bovine pituitary growth hormone (bGH) per kg live weight; (3) daily subcutaneous injection of 1 mg bromocriptine mesilate (Br); (4) daily injections of both bGH and Br at the same rates as treatments (2) and (3).There were no important differences in carcass composition or tissue distribution between the +bGH and +bGH+Br lambs or between the control and +Br lambs. The +bGH lambs (+bGH and +bGH+Br lambs pooled) contained significantly greater proportions of lean and bone compared with the −bGH lambs (control and +Br lambs pooled). Although carcass composition was altered by bGH treatment, the distribution of individual tissues (lean, bone and fat) was not influenced significantly.Carcass quality was improved markedly by bGH treatment: subcutaneous fat depth was reduced and the area of the m. longissimus lumborum increased. +bGH carcasses would be ranked one fat class less on the Meat and Livestock Commission fatness scale than −bGH carcasses at the same carcass weight.

Responses of sheep to annual cycles in nutrition 1. Rôle of endogenous growth hormone during undernutrition

1996 ◽  
Vol 62 (2) ◽  
pp. 279-286 ◽  
Author(s):  
N. R. Adams ◽  
J. R. Briegel ◽  
R. D. G. Rigby ◽  
M. R. Sanders ◽  
R. M. Hoskinson
Keyword(s):  
Growth Hormone ◽  
Weight Loss ◽  
Plasma Concentrations ◽  
Live Weight ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Corpora Lutea ◽  
Annual Cycles ◽  
Wool Growth ◽  
And Control

AbstractPlasma concentrations of growth hormone (GH) are elevated in sheep during undernutrition. The present study attempted to determine whether this increased secretion mediated nutritional effects on reproduction or wool growth, using sheep immunized against growth hormone-releasing hormone and given a low-quality, sub-maintenance diet. Immunization reduced plasma concentrations of GH at all times measured (P < 0·01), through reduced pulse frequency, reduced pulse amplitude, and reduced baseline concentrations. Plasma insulin-like growth factor-1 (1GF-1) was also reduced in the immunized sheep (P < 0·01). Despite this, rates of live-weight loss and wool growth were similar in immunized and control ewes. Plasma concentrations ofLH and FSH were also similar in immunized and control ewes, both during the late luteal phase and after ovariectomy and supplementation with oestradiol and progesterone. Numbers of ovarian follicles and corpora lutea were also unaffected by immunization. It is concluded that high endogenous concentrations of GH in sheep given food below maintenance are necessary to maintain plasma IGF-1, but do not affect the concentration of gonadotropins or ovarian follicular growth. Furthermore, rates of live-weight loss and the depression in wool growth in such animals were also independent of concentrations ofGH or IGF-1.

Production responses of lambs immunized against somatostatin

1991 ◽  
Vol 53 (3) ◽  
pp. 339-344 ◽  
Author(s):  
A. S. Zainur ◽  
R. M. Hoskinson ◽  
R. C. Kellaway
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Live Weight ◽  
Carcass Composition ◽  
Food Conversion ◽  
Eating Pattern ◽  
Inhibiting Factor ◽  
Wool Growth ◽  
And Control ◽  
Food Conversion Efficiency

AbstractThe production responses of crossbred lambs [Poll Dorset (♂ × (Border Leicester ♂ × Merino ♀)] immunized against somatostatin (sornatotropin release inhibiting factor; SRIF) and whose mothers were also given anti-somatostatin vaccination was investigated in this study. There were no significant differences between immunized and control lambs in term of live-weight gain, food intake, food conversion efficiency, digestibility, eating pattern, wool growth and carcass composition. The concentration of growth hormone in plasma of immune lambs was not significantly elevated, even though the lambs had a generally increasing anti-SRIF antibody titre during the experiment. The findings suggest that although the lambs were successfully immunized against SRIF, homeorhetic mechanisms maintained growth hormone and productivity traits within normal levels.

Effects of dietary protein and energy intakes on growth hormone, insulin, glucose tolerance and fatty acid synthesis in young wether sheep

1987 ◽  
Vol 44 (1) ◽  
pp. 143-152 ◽  
Author(s):  
G. C. Waghorn ◽  
D. S. Flux ◽  
M. J. Ulyatt
Keyword(s):  
Growth Hormone ◽  
Fatty Acid ◽  
Glucose Tolerance ◽  
Plasma Concentrations ◽  
Live Weight ◽  
Acid Synthesis ◽  
Weight Changes ◽  
Partial Correlations ◽  
Daily Intakes ◽  
Plasma Gh

ABSTRACTA group of 16 Romney wether sheep fitted with rumen and abomasal cannulae and aged 11 to 12 months was allocated to either high or low crude protein (CP) pelleted diets (220 (HP) and 120 (LP) g CP per kg) to give four daily intakes of dry matter (356, 711, 1067 and 1422 g) within each diet, giving two sheep per treatment. Diets were given hourly for 40 days during which time growth rates, plasma concentrations of insulin (I) and growth hormone (GH) were determined, a glucose tolerance test was performed and relative rates of fatty acid (FA) synthesis were determined.Live-weight changes ranged from –46 to 215 g/day and wool growth ranged from 86 to 210 mg per 100 cm2daily.Plasma GH concentrations were significantly higher (P< 0·001) in sheep given LP diets (21·2 (s.e. 4·2) μg/1) than in those given HP diets (10·1 (s.e. 1·8) μg/1) and negatively correlated with both energy (E) (r= –0·62;P< 0·01) and nitrogen (N) (r= –0·63;P< 0·01) intakes which proportionately accounted for 0·47 of the variance in plasma GH concentration (P< 0·01). Plasma I concentrations were higher (P< 0·05) in sheep given HP diets (2·77 (s.e. 0·34) μg/1) than in sheep given LP diets (1·86 (s.e. 0·23) μg/1). Intakes of E and N proportionately accounted for 0·38 of variance in I concentration which was primarily determined by N intake.After intravenous infusion of glucose (150 mg/min) for 30 min, significant differences in the rate at which plasma glucose and I concentrations declined to pre-infusion levels were evident with different daily intakes of the pelleted diets.Synthesis of FA in adipose tissue was on average 1·7 times more rapid in sheep given HP than in sheep given LP diets (P< 0·05) and increased approximately three-fold with increasing intake. Partial correlations showed differences in E and N intakes were able to account for 0·73 (P< 0·01) of the variance in FA synthesis rates, with N intake having a greater influence than E intake (partial correlations:r= 0·53;P< 0·05 andr= 0·35;P> 0·05 respectively).

The nutrition of artificially reared lambs. 3. The effect of sex on the performance and carcass composition of lambs subjected to different nutritional treatments

1973 ◽  
Vol 16 (1) ◽  
pp. 49-57 ◽  
Author(s):  
J. A. Morgan ◽  
J. B. Owen
Keyword(s):  
Protein Content ◽  
Energy Content ◽  
Live Weight ◽  
Carcass Composition ◽  
Restricted Feeding ◽  
Rubber Ring ◽  
Voluntary Feed Intake ◽  
Lower Protein ◽  
Ad Libitum ◽  
Milk Feeding

SUMMARYForty-eight Suffolk cross lambs were reared artificially from 2 days of age. Sixteen entire males, 16 castrates (castrated by rubber ring at 2 days) and 16 female lambs were allocated at random to a set of 2×2×2 factorial treatments in which feeding was ad libitum or restricted for each of three growth periods—from 2 days old to 15 kg, from 15 to 25 kg and from 25 to 40 kg live weight.The results showed no apparent interaction of sex and feeding treatment and differences due to sex were apparent only in the period after 25 kg live weight. Entire males grew faster and were more efficient at this stage although there was little difference in voluntary feed intake. Carcasses of the males were lower in fat and energy content and higher in protein content than those of females and castrates.The feeding treatments in the main had similar effects to those shown in other studies in the series. Restricted milk feeding was compensated for by increased solid food consumption during the milk-feeding stage but in this experiment there was no tendency for restricted lambs to eat more and grow faster when fed ad libitum in the following period. Restricted feeding in the last period, particularly if preceded by restricted feeding, gave higher killing-out percentage, higher fat content and lower protein content in the carcass than feeding ad libitum. This finding was partly explained by the higher weight of the carcasses of the restricted lambs.

Effect of nutritional growth restriction on timing of reproductive development and plasma concentrations of insulin-like growth factor-1 and growth hormone in male red deer (Cervus elaphus) reared in constant photoperiod

1995 ◽  
Vol 61 (1) ◽  
pp. 155-160 ◽  
Author(s):  
C. L. Adam ◽  
C. E. Kyle ◽  
P. Young ◽  
T. Atkinson
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Red Deer ◽  
Plasma Concentrations ◽  
Live Weight ◽  
Reproductive Development ◽  
Growth Restriction ◽  
Plasma Testosterone ◽  
Insulin Like Growth Factor ◽  
Ad Libitum

AbstractThe effect of nutritional growth restriction on reproductive development in red deer stags reared in constant photoperiod was investigated and the correlation between reproductive status and circulating concentrations of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) examined.Stags were reared from birth in constant photoperiod (12 h light: 12 h dark). They were offered a ‘complete diet’ ad libitum until they reached 52-5 kg live weight (LW) and were then maintained at this LWby restricting daily food dry-matter intake (DMI)for either a long (LR, 26 to 51 weeks of age, no. = 5) or short (SR, 21 to 33 weeks, no. = 6) period before being returned to ad libitum feeding.Relative to SR stags, antlers hardened later in LR stags (72·0 v. 57·5 weeks of age, P < 0·001); sustained elevations in plasma testosterone also began later (55·2 v. 38·5 weeks, P < 0·001) but at lower LW (54·0 v. 60·6 kg, P < 0·05). In both groups, the testosterone rise followed the return to ad libitum food by 4 to 5 weeks. Plasma IGF-1 was closely correlated with DMI (LR, r = 0·84, P < 0·001; SR, r = 0-93, P < 0·001) and with plasma testosterone (LR, r = 0·42, P < 0·001; SR, r = 0·38, P < 0·01). Also the increase in plasma IGF-1 preceded that of testosterone (by 2·8 (s.e. 0·94) weeks) and was associated with a transient plasma GH peak (P < 0·05) and elevated LH concentrations (SR, P < 0·01; LR, P < 0·05).The timing of reproductive development in growth-restricted male red deer in constant photoperiod may therefore be more sensitive to DMI than LW, and changes in plasma IGF-1 concentrations are consistent with a putative permissive role in relaying this information.

The effect of daylength on the growth of lambs. 1. Comparisons of sex, level of feeding, shearing and breed of sire

1979 ◽  
Vol 29 (1) ◽  
pp. 33-42 ◽  
Author(s):  
J. M. Forbes ◽  
A. A. El Shahat ◽  
R. Jones ◽  
J. G. S. Duncan ◽  
T. G. Boaz
Keyword(s):  
Control Mechanism ◽  
Live Weight ◽  
Conversion Ratio ◽  
Carcass Composition ◽  
The Other ◽  
Central Control ◽  
Restricted Feeding ◽  
Food Conversion ◽  
Ad Libitum ◽  
Gut Fill

ABSTRACTTwo experiments were carried out with crossbred lambs which had been weaned in July when 16 weeks old. From early September they were kept in a light-proof building with 12 h artificial light per day for 3 weeks and then half were exposed to 16 h and half to 8 h light per day for a further 16 weeks.Experiment 1 included 72 lambs (48 castrated males and 24 females) and half in each daylength were fed on a concentrated ration ad libitum; the other half were restricted to 70 g/kg live weight0·75 per day. Half of each group were shorn. Lambs kept in 16 h light per day grew significantly faster than those in short daylength at both levels of feeding. Food conversion ratio was best in the 16 h restricted sheep. Unshorn lambs had heavier carcasses than shorn lambs. Long daylength stimulated general growth of the animal without markedly affecting carcass composition, irrespective of level of feeding, whereas ad libitum feeding resulted in much fatter carcasses than did restricted feeding. Gut fill was significantly greater in long-daylength sheep.Experiment 2 included 24 individually penned castrated male lambs, 12 of which were sired by Suffolk rams and 12 by Oxford rams; all were fed at the restricted level. Long daylength significantly stimulated weight gain, especially in the Oxford-cross lambs, but the increase in carcass weight was not significant in this experiment due to the large effect on gut fill.It was concluded that long daylength stimulated growth and gut fill by some central control mechanism and not merely by encouraging more eating.

Pre-pubertal mammogenesis in the sheep 2. The effects of level of nutrition on the plasma concentrations of growth hormone, insulin and prolactin at various ages in female lambs and their relationship with mammary development

1985 ◽  
Vol 41 (3) ◽  
pp. 333-340 ◽  
Author(s):  
I. D. Johnsson ◽  
I. C. Hart ◽  
A. D. Simmonds ◽  
S. V. Morant
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
Live Weight ◽  
High Protein Diet ◽  
High Energy ◽  
Mammary Development ◽  
Similar Response ◽  
Plasma Prolactin ◽  
Once Daily ◽  
Plasma Gh

AbstractFemale crossbred lambs were given a high energy and high protein diet in varying amounts to achieve either high (H; 220 g/day) or low (L; HOg/day) rates of live-weight gain during two consecutive periods between 4 and 20 and 20 and 36 weeks of age. Blood samples were collected via jugular catheters at either 1-h or 2-h intervals over a 28-h period from five lambs on each rearing treatment at 10, 14, 18, 26 and 34 weeks of age for the measurement of prolactin, growth hormone (GH) and insulin. In addition, samples were collected within 2 weeks of slaughter from all eight lambs on each treatment that were slaughtered at either 20 weeks (L and H treatments) or 36 weeks of age (LL, LH and HL treatments) for the assessment of mammary development.The timing of once-daily feeding influenced the plasma profiles of all three hormones measured, but became less obvious with increasing age. Both mean plasma GH, and the influence of level of nutrition on the mean, declined with increasing age. Mean plasma insulin increased with age but did not differ between rearing treatments until 26 weeks, despite large differences in food intake. Mean plasma prolactin in H lambs increased significantly between 10 and 18 weeks, but a similar response did not occur in L lambs. The greater mammary development of L lambs was associated with increased plasma concentrations of GH and reduced concentrations of prolactin. However, the large variation in total mammary parenchymal deoxyribonucleic acid between individuals within each rearing treatment at 20 or 36 weeks of age was not consistently explained by the variation in any of the hormones measured.

The effects of environmental temperature and method of feeding on the performance and carcass composition of bacon pigs

1967 ◽  
Vol 9 (2) ◽  
pp. 209-218 ◽  
Author(s):  
D. W. Holme ◽  
W. E. Coey
Keyword(s):  
Environmental Temperature ◽  
Average Daily Gain ◽  
Carcass Composition ◽  
Restricted Feeding ◽  
Feed Conversion ◽  
Feeding Method ◽  
Feeding Regimes ◽  
Higher Temperature ◽  
Ad Libitum ◽  
Environmental Temperatures

A trial designed to investigate the effects of two environmental temperatures, three feeding regimes and the interactions between them is described. A temperature of 72° F. was better than one of 54° F. for bacon pigs between 40 lb. and 200 lb. weight. The higher temperature resulted in faster growth, more efficient feed conversion and increased length of carcass. Other carcass characteristics were not significantly altered. Ad libitum feeding resulted in faster growth and fatter carcasses than restricted feeding, but did not have a significant effect on efficiency of feed conversion. When feed intake was restricted, feeding pigs once daily or twice daily resulted in similar performance and carcass composition.There was a significant interaction between environmental temperature and feeding method for average daily gain in that pigs fed ad libitum grew faster at the low temperature and pigs fed restricted amounts of feed grew faster at the high temperature. No other interaction reached significant levels.

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