scholarly journals Hormonal Development of Mammary Tissue in Dairy Heifers

1951 ◽  
Vol 34 (12) ◽  
pp. 1174-1179 ◽  
Author(s):  
J.F. Sykes ◽  
T.K. Wrenn
Keyword(s):  
Mammary Tissue ◽  
Dairy Heifers ◽  
Hormonal Development

Concentration of penicillin G in mammary tissue and secretion of end-term dairy heifers following systemic prepartum administration of penethamate hydriodide

2009 ◽  
Vol 77 (1) ◽  
pp. 33-36 ◽  
Author(s):  
Pieter Passchyn ◽  
Sofie Piepers ◽  
Ellen Schmitt-Van de Leemput ◽  
Christian Guidarini ◽  
Sarne De Vliegher
Keyword(s):  
Intramuscular Injection ◽  
Systemic Treatment ◽  
Local Therapy ◽  
Late Gestation ◽  
Penicillin G ◽  
Mammary Tissue ◽  
Antibiotic Concentration ◽  
Intramammary Infections ◽  
Dairy Heifers ◽  
Single Intramuscular Injection

The aim of this study was to assess the concentration of penicillin G in mammary tissue and secretion of dry heifers following systemic administration of penethamate hydriodide. Six dairy heifers in late gestation received a single intramuscular injection of 10 g penethamate hydriodide and were sacrificed 24, 48 or 144 h after treatment. Penicillin G concentrations were measured in mammary tissue and secretion samples using HPLC. Penicillin G was detected in the udder of two animals euthanized at 24 h (mammary tissue and secretion) and at 48 h post treatment (mammary secretion only) after administration at concentrations still close to or above MIC90 values reported for the pathogens associated with heifer mastitis. Antibiotic concentration shortly after administration will have been substantially higher indicating a potential for systemic treatment with penethamate hydriodide to control prepartum intramammary infections in heifers without the disadvantages of local therapy such as teat contamination or risk of trauma for the administrator.

Observations on mammary development in calves and lambs

1953 ◽  
Vol 43 (4) ◽  
pp. 413-421 ◽  
Author(s):  
C. Wallace
Keyword(s):  
Experimental Treatment ◽  
Mammary Development ◽  
Prolonged Treatment ◽  
Mammary Tissue ◽  
Striking Difference ◽  
Oestrogen Treatment ◽  
Beef Breed ◽  
Beef Calves ◽  
Dairy Heifers ◽  
Gland Tissue

The normal course of mammary development has been briefly described, in sheep from 2 months of foetal age to 4 months after birth; and in dairy cattle from the 3-month foetus to calves 6 months old. Observations were also made on a series of udders from ewes during their first pregnancy. A small group of beef calves and a number of freemartins of various ages were also examined.Development was found to be closely similar in the two species, and in both, sex differences were marked.Experimentally it was found that in males of either species castration at birth had little effect on mammary growth, while prolonged treatment with oestrogen gave rise to enlarged teats, dilated cisterns and ducts, and to a certain amount of secretion. Little gland tissue was formed in oestrogen-treated males, and there was no increase in the spreading of mammary tissue from the neighbourhood of the teat.Females of the two species showed a striking difference in their response to experimental treatment. In sheep, removal of the ovaries at birth had no apparent effect on mammary development up to 4 months, while treatment with oestrogen stimulated gland formation in both spayed and intact lambs and also restricted the normal spread of mammary tissue into the udder. In cattle, on the other hand, heifers spayed at birth showed almost complete cessation of mammary development, while implants of oestrogen, in addition to inducing gland formation, promoted the spreading of tissue into the udder pad of the spayed animal.Udder development of freemartins appeared to be similar to that of normal heifers from 5 months foetal age to about a month after birth, but thereafter was more like that of a spayed animal. Removal of the abnormal gonads shortly after birth had no effect, while oestrogen treatment induced development of teats, ducts and glands exactly as in a normal heifer.Comparing small numbers of calves of the two types, it was found that heifers of the beef breed in general showed slightly poorer mammary development than dairy heifers that had been treated in the same way, with more connective tissue and numerous leucocytes in the mammary zone.

Separate and additive stimulation of bovine milk yield by the local and systemic galactopoietic stimuli of frequent milking and growth hormone

1992 ◽  
Vol 59 (3) ◽  
pp. 243-252 ◽  
Author(s):  
Christopher H. Knight ◽  
J. Eric Hillerton ◽  
Marian A. Kerr ◽  
Rachel M. Teverson ◽  
Alan Turvey ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Milk Yield ◽  
Combined Treatment ◽  
Bovine Milk ◽  
Frequency Component ◽  
Mammary Tissue ◽  
Dairy Heifers ◽  
End Of Treatment ◽  
Milking Frequency

SummaryLactating heifers were treated for 4 weeks with recombinant bovine growth hormone (bGH, n = 9) or were untreated (n = 9). In addition, two mammary glands of each heifer were milked four times daily rather than the normal twice daily for the same 4 weeks, and for the following 2 weeks. Over the 4 weeks, milk yield was increased 12·8% by bGH, 14·0% by frequent milking and 28·5% by the combined treatment. The effect of bGH as administered here was slower in onset than that of frequency, but eventually produced a higher peak yield. ANOVA revealed significant effects of each stimulus independently and an additive, but not synergic effect of the combined treatment. The effect of the combined treatment tended to persist beyond the end of treatment; most of this response was related to the milking frequency component rather than the bGH. Mammary differentiation was assessed in biopsies of mammary tissue obtained prior to and at the end of treatment. Mammary enzyme activities (expressed on a per cell basis) indicated minimal differentiative response to either treatment, but synthesis rates for lactose and casein determined in vitro were increased by bGH treatment. Histological examination revealed a stimulatory effect of milking frequency on epithelial cell size. The results indicate that these two galactopoietic stimuli operate through independent mechanisms, and neither stimulus alone is sufficient to maximize milk yield in dairy heifers.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of Lactating Sows

1995 ◽  
Vol 73 (suppl_2) ◽  
pp. 36 ◽  
Author(s):  
Dean R Boyd ◽  
Ronald S Kensinger ◽  
Robert J Harrell ◽  
Dale E Bauman
Keyword(s):  
Nutrient Uptake ◽  
Mammary Tissue ◽  
Endocrine Regulation ◽  
Lactating Sows

scholarly journals Reduction of body-weight gain enhances in vitro embryo production in overfed superovulated dairy heifers

Reproduction ◽  
2006 ◽  
Vol 131 (4) ◽  
pp. 783-794 ◽  
Author(s):  
S Freret ◽  
B Grimard ◽  
A A Ponter ◽  
C Joly ◽  
C Ponsart ◽  
...  
Keyword(s):  
Weight Gain ◽  
Dietary Intake ◽  
Live Weight ◽  
Reproductive Hormones ◽  
Embryo Production ◽  
Live Weight Gain ◽  
Dairy Heifers ◽  
Period 2 ◽  
Significant Difference

The aim of our study was to test whether a reduction in dietary intake could improve in vitro embryo production in superovulated overfed dairy heifers. Cumulus–oocyte complexes of 16 Prim’ Holstein heifers (14 ± 1 months old) were collected by ovum pick-up (OPU), every 2 weeks following superovulation treatment with 250 μg FSH, before being matured and fertilized in vitro. Embryos were cultured in Synthetic Oviduct Fluid medium for 7 days. Heifers were fed with hay, soybean meal, barley, minerals and vitamins. From OPU 1 to 4 (period 1), all heifers received individually for 8 weeks a diet formulated for a 1000 g/day live-weight gain. From OPU 5 to 8 (period 2), the heifers were allocated to one of two diets (1000 or 600 g/day) for 8 weeks. Heifers’ growth rates were monitored and plasma concentrations of metabolites, metabolic and reproductive hormones were measured each week. Mean live-weight gain observed during period 1 was 950 ± 80 g/day (n = 16). In period 2 it was 730 ± 70 (n = 8) and 1300 ± 70 g/day (n = 8) for restricted and overfed groups respectively. When comparing period 1 and period 2 within groups, significant differences were found. In the restricted group, a higher blastocyst rate, greater proportions of grade 1–3 and grade 1 embryos, associated with higher estradiol at OPU and lower glucose and β-hydroxybutyrate, were observed in period 2 compared with period 1. Moreover, after 6 weeks of dietary restriction (OPU 7), numbers of day 7 total embryos, blastocysts and grade 1–3 embryos had significantly increased. On the contrary, in the overfed group, we observed more <8 mm follicles 2 days before superovulation treatment, higher insulin and IGF-I and lower nonesterified fatty acids in period 2 compared with period 1 (no significant difference between periods for embryo production). After 6 weeks of 1300 g/day live-weight gain (OPU 7), embryo production began to decrease. Whatever the group, oocyte collection did not differ between period 1 and 2. These data suggest that following a period of overfeeding, a short-term dietary intake restriction (6 weeks in our study) may improve blastocyst production and embryo quality when they are low. However, nutritional recommendations aiming to optimize both follicular growth and embryonic development may be different.

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