Effect of long-term administration of human growth hormone-releasing factor and(or) thyrotropin-releasing factor on milk production, insulin-like growth factor-I and plasma constituents in dairy cows

1991 ◽  
Vol 71 (3) ◽  
pp. 707-715
Author(s):  
P. Lacasse ◽  
J. Morisset ◽  
D. Petitclerc ◽  
G. Pelletier ◽  
Y. Couture ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Dairy Cows ◽  
Milk Production ◽  
Feed Efficiency ◽  
Human Growth ◽  
Daily Weight Gain ◽  
Average Daily Weight Gain ◽  
Growth Hormone Releasing Factor ◽  
Injection Period ◽  
Factor I

Forty-seven Holstein cows (51 ± 7 d of lactation; 607 ± 78 kg BW) were randomly subjected to a 2 × 2 factorial arrangement based on milk production. Milk production and feed intake were recorded every day and milk and feed composition determined once a week for 33 wk (4 wk preinjection, 26 wk of injection and 3 wk postinjection). During the injection period, cows received daily s.c. injections (10:00 h) in the cervical area of saline (control), human growth hormone-releasing factor (1–29)NH2 (GRF; 10 μg kg−1 BW), thyrotropin-releasing factor (TRF; 1 μg kg−1 BW) or the combination of both releasing factors (10 and 1 μg kg−1 BW, respectively). Growth hormone-releasing factor enhanced milk production (P < 0.001; 22.1 vs. 24.2 kg 4% FCM per d), feed intake (P < 0.05; 19.0 vs. 19.8 kg DM per d), feed efficiency (P < 0.05; 1.14 vs. 1.21 kg 4% FCM per kg DM) and insulin-like growth factor-I concentrations (P < 0.05) but did not affect milk composition (P > 0.25) or average daily weight gain (P > 0.25). Thyrotropin-releasing factor did not affect nor did it interact with GRF on any of these variables except for average daily weight gain which was reduced by TRF (P < 0.05; 0.24 vs. 0.12 kg d−1) during the injection period. Milk production of GRF-treated cows returned to control levels after 3 wk following cessation of treatment. GRF treatment depressed (P < 0.05) serum urea, creatinine, triglycerides and glutamate pyruvate transaminase concentrations, while TRF treatment increased glucose levels (P < 0.05). In conclusion, daily s.c. injections of GRF for 6 months stimulated milk production by 9.5% and improved feed efficiency by 6.1% in dairy cows. Key words: GRF, TRF, milk production, plasma constituents, IGF-I

EFFECT OF A GROWTH HORMONE-RELEASING FACTOR ANALOG ON GROWTH HORMONE, INSULIN-LIKE GROWTH FACTOR 1 AND MILK PRODUCTION IN DAIRY COWS

1990 ◽  
Vol 70 (2) ◽  
pp. 525-535 ◽  
Author(s):  
H. LAPIERRE ◽  
G. PELLETIER ◽  
D. PETITCLERC ◽  
P. GAUDREAU ◽  
P. BRAZEAU ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Dairy Cows ◽  
Milk Production ◽  
Human Growth Hormone ◽  
Block Design ◽  
Human Growth ◽  
Insulin Like Growth Factor ◽  
Growth Hormone Releasing Factor ◽  
Releasing Factors

In a first experiment, 21 cows (98 d in lactation, 609 kg BW) were randomly used to determine the dose-response release of growth hormone (GH) to [desamino-Tyr1, D-Ala2, Ala15] growth hormone-releasing factor (1–29)NH2 analog (GRF-A; 0, 0.12, 0.37, 1.11 and 3.33 μg kg−1 BW) or to human growth hormone-releasing factor (1–29)NH2 (GRF; 3.33 and 10.00 μg kg−1 BW) after s.c. administration. The interaction (P < 0.01) between the two releasing factors and the doses on GH concentrations indicated that the analog was more potent than the original molecule; at the 3.33 μg kg−1 BW dose, the analog elicited a 3.5 times higher GH response than GRF. In a second experiment, the effects of daily s.c. injections for 10 d of either saline, GRF (10 μg kg−1 BW) or GRF-A (0.6 or 1.8 μg kg−1 BW) on GH concentrations and lactational performance were determined using 32 cows (n = 8 per treatment) averaging 91 d in lactation and subjected to a random block design. The three releasing factor treatments similarly increased GH concentrations measured during the 8 h following the injection on d 1 and 10. GRF at the dose of 10 μg kg−1 BW and the analog at the doses of 0.6 and 1.8 μg kg−1 BW increased milk yield by 9.6, 11.7 and 17.6%, respectively, when compared to the control; both releasing factors had no effect on milk composition. Insulin-like growth factor I concentrations were increased 8 h after the last injection, from 73.4 ng mL−1 in control cows to an average of 107.6 ng mL−1 in treated cows. Results show that the [desamino-Tyr1, D-Ala2, Ala15] human growth hormone-releasing factor (1–29)NH2 analog is more potent than human growth hormone-releasing factor (1–29)NH2 in stimulating GH release and milk production in dairy cows. Key words: Growth hormone-releasing factor, analog, growth hormone, milk production, insulin-like growth factor 1, cows (dairy)

EFFECT OF GROWTH HORMONE-RELEASING FACTOR AND(OR) THYROTROPIN-RELEASING FACTOR ON HORMONE CONCENTRATIONS AND MILK PRODUCTION IN DAIRY COWS

1990 ◽  
Vol 70 (1) ◽  
pp. 175-189 ◽  
Author(s):  
H. LAPIERRE ◽  
D. PETITCLERC ◽  
G. PELLETIER ◽  
L. DELORME ◽  
P. DUBREUIL ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Milk Production ◽  
Feed Intake ◽  
Human Growth ◽  
Saline Group ◽  
Milk Composition ◽  
Insulin Like Growth Factor ◽  
Growth Hormone Releasing Factor ◽  
Injection Period

In a 2 × 2 factorial design, 32 cows (n = 8 per treatment) averaging 196 d of lactation received, for 10 consecutive days, daily subcutaneous injections of saline (group 1), human growth hormone-releasing factor (1-29)NH2 (GRF, 10 μg kg−1 BW; group 2), thyrotropin-releasing factor (TRF, 1 μg kg−1 BW; group 3), or GRF (10 μg kg−1 BW) plus TRF (1 μg kg−1 BW; group 4). Blood was collected from 24 cows (n = 6 per treatment) on the first and last day of injection. The synergistic action of the two hypothalamic factors on growth hormone (GH) release was maintained throughout the experiment (P < 0.05). Prolactin (Prl) concentrations increased (P < 0.01) after TRF administration on both sampling days. There was no interaction between the two peptides on thyrotropin (TSH) and thyroxine (T4) concentrations. TSH response to TRF (P < 0.01) observed on the first day was not detectable (P > 0.10) on the 10th day of injection and the TRF-induced T4 response decreased (P < 0.05) from day 1 to day 10. GRF treatment increased (P = 0.06) insulin-like growth factor-I concentrations while TRF had no effect (P > 0.10). Milk production and composition and feed intake were recorded from 10 d before to 10 d after the injection period. Data were averaged for the last 5 d of each 10-d period. Milk production during the injection period averaged 18.8, 20.6, 20.7, and 22.3 kg d−1 for groups 1–4, respectively. Effects of GRF and TRF were additive. Treatment with TRF did not change milk composition but GRF treatment decreased milk protein content. Feed intake did not differ (P > 0.10) between treatments. In summary, the synergy between GRF and TRF on GH concentration was sustained through a 10-d treatment period. Despite this synergy, GRF and TRF had only an additive effect on milk production. Further investigation is needed to confirm whether this successful combination of these two hypothalamic factors can be used on a Song-term basis. Key words: GRF, TRF, milk production, hormone, insulin-like growth factor-1, cows (dairy)

EFFECT OF TWO-MONTH TREATMENT WITH GROWTH HORMONE-RELEASING FACTOR ON MILK PRODUCTION AND PLASMA CONSTITUENTS IN DAIRY COWS

1988 ◽  
Vol 68 (3) ◽  
pp. 741-749 ◽  
Author(s):  
H. LAPIERRE ◽  
G. PELLETIER ◽  
D. PETITCLERC ◽  
P. DUBREUIL ◽  
J. MORISSET ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Feed Intake ◽  
Human Growth ◽  
Milk Composition ◽  
Daily Injection ◽  
Growth Hormone Releasing Factor ◽  
Long Term Treatment

Seventeen dairy cows averaging 252 d of lactation were used to study the effect of long-term treatment with a human growth hormone-releasing factor (hGRF(1–29)NH2) on lactational performance and concentration of plasma constituents. For 57 d, the cows received a daily subcutaneous injection of either saline (S, n = 8) or 10 μg kg−1 BW of hGRF(1–29)NH2 (GRF, n = 9). Milk production and feed intake were recorded daily, while milk composition was determined weekly. Treatment with GRF increased 4% fat-corrected milk yield (13.9 vs. 15.8 kg d−1), and fat yield, (0.58 vs. 0.66 kg d−1). It did not affect protein yield (0.46 vs. 0.52 kg d−1), or feed intake (17.2 vs. 17.8 kg d−1) (means of the 57 d of treatment, S vs. GRF). The GRF-treated cows gained more weight than the control cows, 5.5 vs. 4.2%, respectively. Blood samples were collected hourly, from 2 h before to 8 h after the daily injection on d 1, 15, 29, 43 and 57, to determine plasma constituent concentrations. GRF treatment decreased calcium and cholesterol concentrations, but increased free fatty acids concentration. All constituents measured remained within the normal range. The weights of the cows and their calves and milk yield (14 first wk postpartum) at the subsequent lactation were not affected by previous GRF treatment. In conclusion, treatment with GRF during the last 2 mo of lactation increased milk production and altered levels of some plasma constituents without any detrimental effect on the subsequent lactation. Key words: Growth hormone-releasing factor, milk production, plasma constituents, cows (dairy)

A review of bovine growth hormone

1994 ◽  
Vol 74 (2) ◽  
pp. 167-201 ◽  
Author(s):  
Jeanne L. Burton ◽  
Brian W. McBride ◽  
Elliot Block ◽  
David R. Glimm ◽  
John J. Kennelly
Keyword(s):  
Growth Hormone ◽  
Mammary Gland ◽  
Growth Factor ◽  
Dairy Cows ◽  
Milk Production ◽  
Reproductive Efficiency ◽  
Bovine Growth Hormone ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Exogenous Growth

Unprecedented numbers of technical papers, abstracts, and short communications have been published in the past decade regarding the effects of exogenous bovine growth hormone on milk production, health, and reproductive efficiency of treated dairy cows. In well-managed dairy herds, exogenous growth hormone increases milk production without altering normal variability in milk composition. This has held true regardless of dairy breed tested, geographical location studied, or feeding management system used. Also consistent across studies is the rapidity of the galactopoietic effect of administered bovine growth hormone, which arises from altered partitioning and use of post-absorptive nutrients and increased synthetic capacity of the mammary gland. Growth hormone and its associated peptide, insulin-like growth factor-I, are now known to provide chronic lipolytic, diabetogenic, and gluconeogenic signals to target tissues culminating in increased mammary gland availability of glucose and nonesterified fatty acids. Together with yet ill-defined effects on mammary secretory tissue, this homeorhetic control of metabolism elicited by exogenous growth hormone is so efficient that treated cows are not more susceptible to metabolic disorders than untreated cows. However, some studies have reported an increased frequency of mastitis in groups of treated cows. This has been attributed mainly to increased milk volume in the mammary glands of treated cows and no convincing data are available that show decreased mammary gland immunity as a result of growth hormone treatments. On the contrary, an expanding body of evidence implicates growth hormone as a key neuroendocrine factor that is required for immunological competence. Trends of decreased reproductive efficiency in cows treated with growth hormone have also been reported, but available data imply that this is probably an indirect effect via prolonged negative energy balance in cows treated in early lactation rather than a direct negative effect on estrous cycling via altered reproductive hormone profiles. The objectives of the present review are to bring into focus and summarize pertinent biological discoveries regarding the treatment of dairy cows with recombinant bovine growth hormone, and to explore areas where additional growth hormone research is needed or warranted. Key words: Growth hormone, somatotropin, dairy cows, insulin-like growth factor-I

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