scholarly journals THE RATE OF GROWTH OF THE DAIRY COW

1921 ◽  
Vol 3 (5) ◽  
pp. 623-633 ◽  
Author(s):  
Samuel Brody ◽  
Arthur C. Ragsdale
Keyword(s):  
Dairy Cow ◽  
Growth Period ◽  
Holstein Cows ◽  
Rate Of Growth ◽  
Retarding Effect ◽  
Monomolecular Reaction ◽  
Pregnancy And Lactation

The growth period of the Jersey and Holstein cows is made up of at least three cycles, two extrauterine cycles with maxima at about 5 and 20 months of age, and one intrauterine cycle, the maximum of which has not yet been determined. The equation of an autocatalytic monomolecular reaction was found to give very good results when applied to the cycle having its maximum at about 5 months of age. The values obtained from this equation when applied to the cycle having the maximum at about 20 months of age were higher than the observed values probably due to the retarding effect of pregnancy and lactation on growth.

scholarly journals THE RATE OF GROWTH OF THE DOMESTIC FOWL

1921 ◽  
Vol 3 (6) ◽  
pp. 765-770 ◽  
Author(s):  
Samuel Brody
Keyword(s):  
Guinea Pig ◽  
Domestic Fowl ◽  
Growth Period ◽  
Rate Of Growth ◽  
Monomolecular Reaction

This paper points out the fact that the growth period of the domestic fowl is analogous to that of the mammal, being composed of three, or perhaps four, cycles; two of these cycles are postembryonic with maxima at about 8 and 18 weeks varying somewhat with the breed and two or at least one, are embryonic with maxima at 11 to 12 and 15 to 16 days of age. Hatching occurs during the first part of the second or third cycle resembling in this respect the guinea pig rather than the mouse. The velocity curves of each of these cycles are similar to and can be represented by the equation of an autocatalytic monomolecular reaction.

scholarly journals Effects of dry period length on follicular dynamics in early lactating Holstein cows

2009 ◽  
Vol 2009 ◽  
pp. 134-134
Author(s):  
A Soleimani ◽  
A Heravi Moussavi ◽  
M Danesh Mesgaran ◽  
S Safa
Keyword(s):  
Dairy Cow ◽  
Detrimental Effect ◽  
Good Reason ◽  
Period Length ◽  
Holstein Cows ◽  
Dry Period ◽  
Management Change ◽  
Lactating Cows ◽  
Current Advice ◽  
Follicular Dynamics

For profitable production of milk, a nonlactating or dry period is established between lactations of dairy cow. There has been substantial recent interest in shortening dry periods. Physiological studies show that the changes the udder goes through to prepare for the next lactation take about three weeks, and yet current advice is that the most appropriate dry period for a modern dairy cow is 45 to 60 days. More recent studies show good reason to question that advice, and suggest dry periods of 30 to 35 days have no detrimental effect on production, but information relating the effects of dry period to subsequent reproductive performance of lactating cows is sparse (Grummer, 2007). Also, the effect of this management change on follicular dynamic has not been adequately evaluated. Therefore, the objective of the present study was to determine the effects of dry period length on follicular dynamics in early lactating Holstein cows.

scholarly journals Embryonic mortality in Holstein cows on one’s farm

2011 ◽  
Vol 59 (1) ◽  
pp. 211-218 ◽  
Author(s):  
Petra Puklová ◽  
Jan Šubrt ◽  
Dušan Skrip ◽  
Radek Filipčík
Keyword(s):  
Dairy Cows ◽  
Body Condition ◽  
Dairy Cow ◽  
Body Condition Score ◽  
The Body ◽  
Embryonic Mortality ◽  
Holstein Cows ◽  
Holstein Friesian ◽  
Condition Score ◽  
Positive Effect

The objective of our research was to evaluate the effect of some factors on the embryonic mortality of Holstein-Friesian dairy cows in a herd. Monitoring was conducted in the course of three years (2006–2009) at a level of (9330–8970) kg/dairy cow per lactation. We monitored the reproduction parameters of 209 dairy cows (1st to 8th lactation). Ultrasonography was used to diagnose gravidity, and/or embryonic mortality, in each cow 6 times, at regular 4-day intervals between days 22 and 42 after insemination. We analysed the effect of 3 factors on embryonic mortality: age, body condition score and season of the year at the time of insemination. Embryonic mortality relative to the age of the female was significantly the lowest (20.69 %) in cows aged 42 to 47 months (3.5–3.9 years); high embryonic mortality (45.46 %) was recorded in the youngest females of 24 to 29 months of age (2.0–2.4 years). The results indicated that the body condition score of the cow at the time of insemination had a statistically significant (P > 0.01) effect on embryonic mortality (EM). Embryonic mortality was the lowest when the body condition of the cow was “ideal”, i.e. 5 points of the BCS (at the most 9 points). The season of the year when insemination was carried out had a positive effect on embryonic mortality.

scholarly journals Effects of Subsurface Drip Irrigation on Water Consumption and Yields of Alfalfa under Different Water and Fertilizer Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xuesong Cao ◽  
Yayang Feng ◽  
Heping Li ◽  
Hexiang Zheng ◽  
Jun Wang ◽  
...  
Keyword(s):  
Water Consumption ◽  
Nitrogen Fertilizer ◽  
Drip Irrigation ◽  
Growth Period ◽  
High Water ◽  
Subsurface Drip Irrigation ◽  
Rate Of Growth ◽  
Maximum Water ◽  
Use Efficiency ◽  
Subsurface Drip

A field experiment was conducted for the purpose of examining the effects of different combinations of water and fertilizer applications on the water consumption and yields of alfalfa under subsurface drip irrigation (SDI). The results showed that the jointing and branching stages were the key stages for alfalfa water requirement. The water consumption had varied greatly (from 130 to 170 mm) during the growth period of each alfalfa crop. The water consumption during the whole growth period was approximately 500 mm, and the maximum water consumption intensity was 3.64 mm·d-1. The overall changes in water consumption and yields during the growth period of the alfalfa displayed trends of first increasing and then decreasing. The sensitivities of the yields to water changes were much higher than that of fertilizer. The water use efficiency (WUE) of the alfalfa was determined to range from 1.68 to 3.20 kg·m-3, and the rate of growth had ranged from 4.85% to 51.77%. The WUE and rate of growth of the alfalfa indicated the following trend: second crop > third crop > first crop. The results of frequency analysis based on the water-nitrogen-yield regression equation are the following: irrigation amounts of 142~165 mm and nitrogen application of 61~80 kg·hm-2 have a 95% probability of obtaining a hay yield of alfalfa of more than 11903 kg·hm-2. These results suggest that SDI is a promising irrigation method, which can increase the WUE and hay yield of alfalfa under the condition of SDI within an appropriate amount of water and nitrogen fertilizer, and too low or too high water and nitrogen fertilizer will adversely affect the WUE and hay yield of alfalfa.

scholarly journals THE GROWTH AND DURATION OF LIFE OF CELOSIA CRISTATA SEEDLINGS AT DIFFERENT TEMPERATURES

1934 ◽  
Vol 17 (6) ◽  
pp. 763-781 ◽  
Author(s):  
Thomas I. Edwards ◽  
Raymond Pearl ◽  
Sophia A. Gould
Keyword(s):  
Growth Rate ◽  
Maximum Yield ◽  
Total Duration ◽  
Growth Curves ◽  
Growth Period ◽  
Hypocotyl Length ◽  
Rate Of Growth ◽  
Life Duration ◽  
Celosia Cristata ◽  
The Mean

Daily measurements of hypocotyl length were made on Celosia cristata seedlings cultured in darkness under aseptic conditions at six constant temperatures between 14.5° and 40.5°C. At 40.5° roots did not penetrate the agar and only the hypocotyls that were supported by the wall of the test tube could be measured. The growth curves were of the generalized logistic type, but of different degrees of skewness. The degree of symmetry of the growth curves was influenced by temperature. At the lower temperatures the maximal growth rate came relatively late in the grand period of growth; at successively higher temperatures it came progressively earlier. The mean total time rate of growth (millimeter per diem) was found to be a parabolic function of the temperature. The maximum rate of growth was found from the curve to be at 30.48°C. The maximum observed rate of growth, and the maximum yield, were found to be at 30°C. At all temperatures above 14.5° the maximum growth activity fell in the second quarter of the whole growth period. At all temperatures tested other than 30°, and at all parts of the growth cycle, the growth yield as measured by height of hypocotyl at any given equivalent point was less than at 30°. The total duration of life of the seedlings, and the duration of life after the end of the growth period (intermediate period) were inversely proportional to the mean total growth rate. The observations on Celosia cristata seedlings are thus in accord with the "rate of living" theory of life duration. The optimal temperature for life duration is the minimum temperature, within the range of these observations.

Fleece growth in Australian cashmere goats. II. The effect of pregnancy and lactation

1993 ◽  
Vol 44 (5) ◽  
pp. 1023 ◽  
Author(s):  
WRL Kloren ◽  
BW Norton
Keyword(s):  
Growth Rate ◽  
Hair Growth ◽  
Growth Cycles ◽  
Rate Of Growth ◽  
Delayed Initiation ◽  
Pregnancy And Lactation ◽  
Cashmere Goats

Groups of Australian cashmere does were randomly assigned to December, March, July and September kidding groups in two successive years, and cashmere and hair growth was compared to does not kidding in each year. There was no significant (P > 0.05) effect of kidding time on cashmere growth rate. Kidding in December significantly (P < 0.05) delayed initiation of cashmere growth by around 2 weeks and occurred around February. Half of the does kidding in March failed to grow cashmere, and of the others, initiation date or rate of growth was not affected. Kidding in July advanced the cessation of cashmere growth to May compared with July in control does. Does kidding in September had cashmere growth cycles similar to those of control goats; however, fleece regrowth following shearing in June was significantly (P < 0.05) less. There were no consistent effects of kidding time on hair growth, but regrowth was significantly (P < 0.05) greater in the March kidding group following shearing in June.

Growth and Phosphate Absorption in Lettuce and Cabbage Plants in Dilute Solution Culture

1977 ◽  
Vol 4 (4) ◽  
pp. 505 ◽  
Author(s):  
MG Temple-Smith ◽  
RC Menary
Keyword(s):  
Dry Matter ◽  
Maximum Yield ◽  
Growth Period ◽  
Solution Culture ◽  
Lower Solution ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Phosphate Absorption ◽  
Rate Of Growth ◽  
Total Plant

Growth and phosphate absorption of lettuce and cabbage plants were compared at seven solution phosphate concentrations in the range 0.06-8.0 �M. Phosphate levels were maintained constant throughout the 35-day growth period by the use of large volume (450 litres per 24 plants) continuous- flow solution culture units. Both lettuce and cabbage achieved maximum relative growth rates of approximately 14 g dry matter per 100 g dry matter per day. For cabbage this rate of growth was achieved at a solution phosphate concentration of 0.5 �M. However, to attain the same rate of growth, lettuce required a solution phosphate level at least fourfold greater (between 2.0 and 4.0 �M) . These phosphate concentrations are many times lower than those previously reported for maximum yield of these species. The ability of cabbage to achieve maximum dry matter yield at lower solution phosphate concentrations than that required by lettuce appears to be due to a combination of its greater rate of phosphate absorption per unit of root at low phosphate concentrations, its higher proportion of total plant phosphorus and dry matter contained in the shoot, and its higher phosphate utilization quotient at maximum yield.

Mechanism of Exposure-Cracking of Rubbers. With a Review of the Influence of Ozone

1945 ◽  
Vol 18 (3) ◽  
pp. 504-556 ◽  
Author(s):  
R. G. Newton
Keyword(s):  
Surface Strain ◽  
Ozone Absorption ◽  
Surface Protection ◽  
Rate Of Growth ◽  
Retarding Effect ◽  
Actual Growth ◽  
Small Cracks ◽  
Formation Of Cracks ◽  
The Mean ◽  
Marked Resistance

Abstract “Exposure-cracking” is the fissuring which occurs when stretched rubber is placed in an atmosphere containing ozone, and is frequently wrongly described as “sun-cracking”. These cracks form in the rubber at right angles to the applied stress and must be distinguished from crazing, the fissures of which occur in an oxidized surface layer and may run in any direction. It is shown that there is a “critical elongation” at which cracking is maximal, but that the relation between the severity of cracking and the surface strain can be greatly modified by changes in the compounding ingredients. Butadiene type of rubbers do not differ greatly in resistance to exposure-cracking, whereas the Neoprene types and Thiokol-FA possess marked resistance. The only factors essential for the production of exposure-cracking are ozone and strain in the sample, and sufficient ozone must be present in the atmosphere to produce the deterioration observed. Light is not only unnecessary, but actually has a retarding effect on the production of cracks. Three different phenomena must be carefully distinguished (1) the rate of ozone attack ; (2) the rate of formation of cracks ; and (3) the rate of growth of cracks. The rate of formation of cracks increases with increase of strain until a maximum is reached at about 75 per cent elongation, but the mean rate of growth of cracks is most rapid at 20 per cent elongation because the surface strain is most persistent at this elongation. The actual growth of cracks has been studied microscopically, and it is shown that large cracks are formed by the coalescence of small cracks, and the collapse of neighboring ones. The rate of ozone absorption is considered, and speculations are advanced to explain the formation of cracks and their greater incidence at high strains. The course of ozone attack indicates that there is little likelihood of producing improvement in resistance by altering compounding ingredients such as fillers and antioxidants, and confirms that the most efficient methods will be based on some type of surface protection.

scholarly journals THE RATE OF GROWTH OF THE DAIRY COW

1924 ◽  
Vol 6 (3) ◽  
pp. 329-336
Author(s):  
Samuel Brody ◽  
Arthur C. Ragsdale
Keyword(s):  
Dairy Cow ◽  
Chemical Process ◽  
Exponential Law ◽  
Rate Of Growth ◽  
Linear Dimensions ◽  
Constant Rate ◽  
The Law ◽  
The Given ◽  
Cyclic Phenomena ◽  
Constant Percentage

Barring fluctuations due to the cyclic phenomena, the extrauterine course of growth in linear dimensions and in weight of the dairy cow follows an exponential law having the same form as the law representing the course of monomolecular change in chemistry. This suggests the interpretation that the general course of growth is limited by a monomolecular chemical process, and that the cyclic phenomena are due to subsidiary processes in the fundamentally exponential course of growth. The fact that growth follows or tends to follow an exponential course may be stated more simply as follows: if the unit of time is taken sufficiently large so that fluctuations due to the cyclic phenomena are balanced or eliminated, then the amount of growth made during the given unit of time at any age tends to be a constant percentage of the growth made during the preceding unit of time. Thus, the growth in height at withers made during any year is about 34 per cent of the growth made during the preceding year. Similarly the growth in weight made during any year is about 56 per cent of the growth in weight made during the preceding year. This is in accordance with expectations if it is assumed that each animal begins life with a definite endowment of limiting substance necessary for the process of growth, and that this endowment is used up at a constant rate (or percentage) of itself.

scholarly journals Elevation of circulating serotonin improves calcium dynamics in the peripartum dairy cow

2016 ◽  
Vol 230 (1) ◽  
pp. 105-123 ◽  
Author(s):  
Samantha R Weaver ◽  
Austin P Prichard ◽  
Elizabeth L Endres ◽  
Stefanie A Newhouse ◽  
Tonia L Peters ◽  
...  
Keyword(s):  
Dairy Cow ◽  
Therapeutic Benefit ◽  
Holstein Cows ◽  
Calcium Dynamics ◽  
Total Calcium ◽  
Serotonin Synthesis ◽  
Peripartum Period ◽  
Jersey Cows ◽  
Potential Therapeutic Benefit ◽  
Infusion Period

Hypocalcemia is a metabolic disorder that affects dairy cows during the transition from pregnancy to lactation. Twelve multiparous Holstein cows and twelve multiparous Jersey cows were intravenously infused daily for approximately 7 days prepartum with either saline or 1.0mg/kg bodyweight of the immediate precursor to serotonin synthesis, 5hydroxy-l-tryptophan (5-HTP). On infusion days, blood was collected before, after, and at 2, 4, and 8h postinfusion. Blood and urine were collected daily before the infusion period, for 14 days postpartum and on day 30 postpartum. Milk was collected daily during the postpartum period. Feed intake and milk yield were unaffected by 5-HTP infusion postpartum. Cows infused with 5-HTP had elevated circulating serotonin concentrations prepartum. Infusion with 5-HTP induced a transient hypocalcemia in Jersey cows prepartum, but not in any other treatment. Holstein cows infused with saline had the highest milk calcium on the day of and day after parturition. Postpartum, circulating total calcium tended to be elevated, and urine deoxypyridinoline (DPD) concentrations were elevated in Holstein cows infused with 5-HTP. Overall, Jerseys had higher urine DPD concentrations postpartum when compared with Holsteins. Taken together, these data warrant further investigation of the potential therapeutic benefit of 5-HTP administration prepartum for prevention of hypocalcemia. Further research should focus on delineation of mechanisms associated with 5-HTP infusion that control calcium homeostasis during the peripartum period in Holstein and Jersey cows.

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