Wood Model Research Articles

Assessing Environmental Effects upon Modeling the Individual Lactation Curve of a Local Goat Population in a Pastoral System.

The present study aims to use Wood's model to determine the parameters of individual lactation curves in a local goat population and their factors of variation under a pastoral system. A total of 137,927 records from 432 local goats were collected to assess the impact of litter size, year and month of kidding, herd and the age of the dam on lactation curve parameters. Wood's model parameters were estimated using non-linear regression, and individual curves were fitted. The characteristics of the lactation curves were computed. The initial yield (A), rate of increase (B) and rate of decline (C) parameters in Wood's model for local goats were 730 g, 0.26 and 0.09 respectively. The values of peak milk production (PP), peak date (PD) and persistency (PC) were 931.88 g/d, 23.39 days and 91.50%, respectively. Persistence was higher in goats with simple births, while peak production increased by around 0.3 kg for each additional kid. The curve parameters "A" and "C" differed according to the herd and month of kidding (p < 0.05); the age of the dam only had an impact on parameter "A" (p < 0.01). Parameter "B" was not significantly influenced by any of the factors considered (p > 0.05). Correlation coefficients among lactation curve characteristics were ranged from -0.20 to 0.89. Due to a significant negative correlation, selecting for parameter "A" may have an adverse effect on parameter "B", resulting in a shorter time to reach peak production and less persistency, but an increase in peak production among goats. The curves derived from Wood's model suggest that the shape of the curve may serve as a basis for herd management planning and to improve local population potentialities.

Genetic aspects of Wood's lactation curve parameters in Jersey crossbred cattle using Bayesian approach.

The study was undertaken to estimate the genetic parameters of lactation curve parameters of Wood's function in Jersey crossbred cattle using the Bayesian approach. Data on 33,906 fortnightly test day milk yields of 1,718 lactation records of Jersey crossbred cows, maintained at the ICAR-National Dairy Research Institute in West Bengal, were collected over a period of 40 years. The lactation curve parameters including 'a' (initial milk yield after calving), 'b' (ascending slope up to peak yield) and 'c' (descending slope after peak yield) and lactation curve traits, peak yield (ymax), time of peak yield (tmax) and persistency of milk yield (P) of individual cow for each lactation were estimated using the incomplete gamma function (Wood's model) by fitting the Gauss-Newton algorithm as an iteration method using PROC NLIN procedure of SAS 9.3. Variance components and genetic parameters of lactation curve parameters/traits were estimated by a repeatability animal model using the Bayesian approach. Estimates of heritabilities were found to be 0.18 ± 0.05, 0.09 ± 0.03 and 0.11 ± 0.04 for parameters 'a', 'b' and 'c', respectively and 0.24 ± 0.05, 0.12 ± 0.04, and 0.15 ± 0.05 for ymax, tmax and P, respectively. Repeatability estimates were 0.31 ± 0.03, 0.21 ± 0.04 and 0.30 ± 0.04 for parameters 'a', 'b' and 'c' respectively and 0.39 ± 0.03, 0.24 ± 0.03 and 0.37 ± 0.03 for ymax, tmax and p, respectively. Genetic correlations among lactation curve parameters/traits ranged from -0.75 to 0.95. Existence of genetic correlations among lactation curve parameters/traits indicated substantial genetic and physiological relationships among lactation curve parameters/traits of Jersey crossbred cattle.

Investigating the effect of temporal, geographic, and management factors on US Holstein lactation curve parameters.

We fit the Wood's lactation model to an extensive database of test-day milk production records of US Holstein cows to obtain lactation-specific parameter estimates and investigated the effects of temporal, spatial, and management factors on lactation curve parameters and 305-d milk yield. Our approach included 2 steps as follows: (1) individual animal-parity parameter estimation with nonlinear least-squares optimization of the Wood's lactation curve parameters, and (2) mixed-effects model analysis of 8,595,413 sets of parameter estimates from individual lactation curves. Further, we conducted an analysis that included all parities and a separate analysis for first lactation heifers. Results showed that parity had the most significant effect on the scale (parameter a), the rate of decay (parameter c), and the 305-d milk yield. The month of calving had the largest effect on the rate of increase (parameter b) for models fit with data from all lactations. The calving month had the most significant effect on all lactation curve parameters for first lactation models. However, age at first calving, year, and milking frequency accounted for a higher proportion of the variance than month for first lactation 305-d milk yield. All parameter estimates and 305-d milk yield increased as parity increased; parameter a and 305-d milk yield rose, and parameters b and c decreased as year and milking frequency increased. Calving month estimates parameters a, b, c, and 305-d milk yield were the lowest values for September, May, June, and July, respectively. The results also indicated the random effects of herd and cow improved model fit. Lactation curve parameter estimates from the mixed-model analysis of individual lactation curve fits describe well US Holstein lactation curves according to temporal, spatial, and management factors.

Estimation of partial lactation milk yields in Saanen goats raised in semi-intensive conditions

Objective: The objective of this study was to estimate the lactation curves of Saanen goats by using individual milk yields in the early, mid and 0-6 months periods of lactation. For this purpose, Wood’s lactation curve was used to estimate lactation yields. Material and Methods: Milk yields of Saanen goats in different periods of lactation were estimated. For this purpose, the Wood’s lactation curve model was adapted to a total of 480 milk yield measured at 14-day intervals of 40 Saanen goats. Milk yields of goats in the first three months of lactation in January-March, mid-lactation in April-June, and 0-6 months in January-June were estimated. Results: According to the harmony of Wood's model, the determination of coefficient values of the estimations of milk yields in the first, mid-lactation and 0-6 months of lactation are 0.84, 0.87 and 0.84, respectively. The root mean square errors of Wood's model are 0.91 for the first period of lactation, 0.81 for the mid-lactation period and 0.30 for the from 0 to 6 months of lactation period. Conclusions: According to the results obtained in this study, Wood's model was found sufficient to define the lactation curve in Saanen goats. However, it would be beneficial to conduct similar studies with larger herds and yield records.

Influence of Lactation Number, Year and Season of Calving on Milk Productivity of Cows

The main characteristics of the milk productivity of Holstein dairy cattle differ in different countries due to differences in terrain, management and breeding objectives. At the same time, the manifestation of non-genetic (that is, environmental) factors during milk production, as a rule, mask the real breeding value of animals. The main goal of this study was to analyze the influence of lactation number, year and season of calving on the milk productivity of 238 Holstein cows during a 4-year period (2014-2017). The study was conducted using primary data on the dairy productivity of livestock in the conditions of PJSC Plemzavod Stepnoi of the Kamian-Dnipro district of the Zaporizhia region.The following characteristics were evaluated for each animal: duration of lactation, hope for 305 days of lactation, hope for the entire lactation, fat content and protein content in milk. P. Wood's model was used to approximate lactation curves within each subgroup. All signs of milk productivity were analyzed based on the algorithm of one- or two-factor analysis of variance with fixed factors using the statistical package STATISTICA v. 6.0 (Statsoft Inc.).Lactation number was found to have a significant effect on all milk yield traits that were examined (in all cases: p&lt;0.001). Hope for 305 days of lactation increased with the growth of lactation number. The highest values of this characteristic were noted during the 2nd and 3rd lactations. The lowest estimate of milk yield for 305 days of lactation of dairy cows of this farm was obtained in 2014, and the highest in 2016. The calving season probably influenced the indicators of milk productivity (primarily, the content of fat and protein in milk) of firstborns. In addition, the milk yield score at 305 days of lactation was lower among winter- or spring-calved gilts compared to fall-calved animals. No influence of the calving season was noted among adult cows. Lactation number and year of calving probably influenced the estimates of the coefficients and parameters of P. Wood's model. The shape of the lactation curves of firstborns was flatter compared to mature cows. Estimates of peak milk yield were lower, but the index of constancy of the lactation curve was higher during the 1st lactation. Thus, we found that obtaining real (unbiased) estimates of milk productivity traits of Holstein cattle requires preliminary adjustment of data regarding the influence of lactation number, year and season of calving

Heterosis effects on 305-day milk yield in a Girolando dairy cattle population in different lactation orders

The aim of this study was to evaluate the heterosis effects for 305-day milk yield (305MY) in different lactation orders of Girolando cows, by fitting test-day milk yield records to Wood's, Mixed Log, and Wilmink's non-linear models. A total of 400,328 test-day milk yield records of 39,077 Holstein (H), Gyr (G), and Girolando (1/2 H, 1/4 H, 3/4 H, 3/8 H, 5/8 H, and 7/8 H genetic groups) cows from 822 herds were collected in the state of Minas Gerais, Brazil, from 1998 to 2014. The pedigree file comprised 36,640 animals, including 3677 sires and 24,472 cows. Genetic parameters were obtained by single-trait analysis using the AIREMLF90 software. Heritability estimates of 305MY and of 305MY fitted to the different non-linear models were higher in the first lactation and ranged from 0.10 to 0.29. We observed a greater heterosis effect for 305MY (and 305MY fitted) verified in cows of genetic group 1/2H, which presented average production superior to the average of their parents (of pure breeds) in the first (1034.33 kg) and second (1303.94 kg) lactation, respectively. Both Wood's and Wilmink's models stood out in quality of fit, presenting the best estimates for 305MY adjusted for different lactation orders. Wood's model is the most suitable to estimate 305MY of cows with a higher proportion of H genes. However, Wilmink's model allows estimating heterosis effects for 305MY and components of the lactation curve more similar to those observed in 305MY in the different genetic groups. The results indicate that local breeders can promote an improvement in milk production through exploitation of the heterosis effect, making choices of genetic combinations (breeders) more suitable for mating to obtain greater economic and productive efficiency of their herds during lactations.

Lactation curves and persistency of White Fulani and Sokoto Gudali lactating cows

The aim of this study was to determine the lactation curve traits of White Fulani (WF) and Sokoto Gudali (SG) lactating cows. Wood's gamma and Wilmink's curve parameters were employed to identify the lactation curve types and values for the parameters beginning yield (a) , coefficient of rising (b), coefficient of decreasing (c)t=timeande= is the exponential.The parameter assumed a fixed value derived from a preliminary analysis and disassociated with the time at peak yield were used to determine the shape and type of lactation curve. All Parameters in a typical lactation curves were positive, and in the event of one parameter being negative, the curve was considered to be an atypical lactation curve. Lactation records from WF (n=96)and SG (n=130) cows were recorded in the study area between year 2016-2017. Cows were hand-milked twice per day in the morning and evening from the 5 day post-partum till the end of the lactation period (260-270 days).Prediction equation of milk yield showed R values ranging from (32.00) in the SG to (35.00) in the WF. It was observed that the Wood's model curves were typical while Wilmink's model curves were atypical respectively. For typical lactation curves, a, b, c, persistency (S), time after parturition until the peak yield occurs (T ), maximum daily peak yield (Y ), and coefficient of determination (R ) were - 0.25±0.13, 1.08±0.07, 0.23±0.19, 2.34,51.00,2.62 and 97 for WF lactating cows and - 0.23 ± 0.14,1.13 ± 0.08, 0.07± 0.03, 2.33, 51.26, 2.58 and 96 for SG Lactating cows respectively. Parameters predicted by the Wood's model have the potential of being useful for breeding programmes in the SG and WF cows.

A teoria dos stakeholders no Brasil: produção acadêmica no período de 2014 a 2019

Objetivo: Analisar o perfil da produção recente sobre Teoria dos Stakeholders nos periódicos nacionais.Método: Revisão de literatura, na qual foram selecionados 271 artigos publicados, entre 2014 e 2019, em 92 periódicos do estrato superior do Qualis/CAPES em Administração e áreas afins. Originalidade/Relevância: O conhecimento acerca do referido perfil auxilia os pesquisadores a visualizarem aspectos metodológicos e conceituais a partir dos quais o tema está sendo discutido, contribuindo para a definição de uma agenda de pesquisa.Resultados: A RBGN, a RAUFSM e a RIAE são os periódicos de referência. A maioria dos estudos adota uma abordagem teórico-empírica e possui natureza qualitativa, sendo a pesquisa documental e a entrevista os instrumentos de coleta de dados mais utilizados. A análise de conteúdo foi a técnica de análise de dados mais aplicada. A definição de Stakeholder de Freeman e o modelo de análise de Mitchell, Agle e Wood são os mais empregados. A pesquisa sobre o tema é crescentemente colaborativa, bem como foi possível constatar a validação das Leis de Bradford e Zipf, mas não a de Lotka. Portanto, é possível identificar um grupo de periódicos mais devotos ao tema e os termos que apresentam maior frequência nos artigos pesquisados. Entretanto, não foi possível comprovar que uma larga proporção da literatura foi produzida por um pequeno número de autores. Contribuições teóricas/metodológicas: Foram identificadas lacunas na literatura e tendências, como o diálogo entre a Teoria de Stakeholder e a geração de valor, que foram objeto da agenda de pesquisa sugerida.

The effect of extended lactation on parameters of Wood's model of lactation curve in dairy Simmental cows.

ObjectiveThis study was focused on the estimation of parameters of Wood’s model and description of the lactation curve using the cows which were lactated over 24 months on the first lactation.MethodsThe database included 1,333 pure-bred dairy Simmental primiparous cows which lactated for 24 months (732 days). The initial dataset entering the procedure of assessment of parameters of Wood’s function included 35,826 milk yield records. Milk yield was recorded throughout lactation, with the earliest record taken on day 6 and the latest on day 1,348 of lactation. This dataset was used for the assessment of parameters a, b, c of Wood’s model using the non-linear statistical procedure. These parameters were estimated for different length of lactation. The assessed parameters were used for calculation of some characteristics of lactation curves.ResultsThe lowest value of a parameter (15.2317) of Wood’s model of lactation curve was found out in lactations up to 305 days long, contrary to b and c parameters which were highest in those lactations (0.1029 and 0.0015, respectively). The maximum value of a parameter (17.4329) was found out in lactations up to 640 days long, unlike b and c parameters which were minimal in those lactations (0.0603 and 0.0010, respectively).ConclusionIt can be concluded that the parameters of Wood’s model and the shape of lactation curve are changing with the growing number of milk yield records. Also, the assessed parameters revealed a significant milk production potential after 305 days of lactation.

Lactation milk yield prediction in primiparous cows on a farm using the seasonal auto-regressive integrated moving average model, nonlinear autoregressive exogenous artificial neural networks and Wood's model.

ObjectiveThe aim of the present study was to compare the effectiveness of three approaches (the seasonal auto-regressive integrated moving average [SARIMA] model, the nonlinear autoregressive exogenous [NARX] artificial neural networks and Wood’s model) to the prediction of milk yield during lactation.MethodsThe dataset comprised monthly test-day records from 965 Polish Holstein-Friesian Black-and-White primiparous cows. The milk yields from cows in their first lactation (from 5 to 305 days in milk) were used. Each lactation was divided into ten lactation stages of approximately 30 days. Two age groups and four calving seasons were distinguished. The records collected between 2009 and 2015 were used for model fitting and those from 2016 for the verification of predictive performance.ResultsNo significant differences between the predicted and the real values were found. The predictions generated by SARIMA were slightly more accurate, although they did not differ significantly from those produced by the NARX and Wood’s models. SARIMA had a slightly better performance, especially in the initial periods, whereas the NARX and Wood’s models in the later ones.ConclusionThe use of SARIMA was more time-consuming than that of NARX and Wood’s model. The application of the SARIMA, NARX and Wood’s models (after their implementation in a user-friendly software) may allow farmers to estimate milk yield of cows that begin production for the first time.

Application of lactation models on dairy cow farms

An important branch of the modern global economy is food production. Our focus is milk production on dairy farms, the period in which cows produce milk (lactation) and the quantity of milk produced. Special attention will be given to the time-dependent function that describes the quantity of the milk produced over a lactation period. The respective graph is known as the lactation curve and is one of the most important indicators in dairy farm management. This paper will present time-dependent parametric models for daily average milk production on a particular dairy farm. Besides the well-known Wood's model, the data will also be fitted to some less known models such as the MilkBot model and also to a combination of these two models. Model parameters will be interpreted relative to milk production. Finally, we will compare all of the observed models.

Lactation curve and milk quality of goats experimentally infected with Trypanosoma vivax

The present study aimed to evaluate the effects of Trypanosoma vivax infection on the shape of the lactation curve and the milk quality of dairy goats experimentally infected with T. vivax. In total, twenty Saanen goats, aged 26–30 months and the same number of calving (two calvings), were divided into two experimental groups: an infected group, consisting of ten goats intravenously infected with 0.5 ml of blood containing approximately 1.25 × 105 trypomastigotes of T. vivax and ten uninfected animals as the control group. Clinical tests and hematocrit, parasitemia, and serum biochemistry evaluations were performed on all of the goats. Milk production was measured daily for 152 days by hand milking the goats and weighing the milk. Every seven days, physiochemical analyses were performed to evaluate the milk. Wood's nonlinear model was used to analyze the lactation curve parameters. The infected goats had high levels of parasitemia and hyperthermia, significantly reduced hematocrit, serum total protein, albumin, and glucose levels and increased cholesterol and urea concentrations. Wood's model indicated that the milk production of goats in the infected group declined sharply over a short period of time and produced a flattened yield curve and significant difference (P < 0.05) in the rate of increase of peak milk production, rate of decrease of milk production after the peak, day of peak milk production, and maximum peak milk production compared with that of the control group. Trypanosomiasis also affected the persistency of lactation, which was significantly reduced in goats in the infected group. In addition, the physico-chemical properties of the milk, including the fat content, defatted dry extracts (DDE) and protein content, decreased significantly (P < 0.05) in the goats in the infected group compared with those in the control group. The T. vivax-infected goats showed reduction in milk production, persistence of lactation, and fat levels, the defatted dry extract (DDE) content, and protein, changing the quality of milk.

Lactation curves and body weight changes of Alpine, Saanen and Anglo-Nubian goats as well as pre-weaning growth of their kids

Thirty-six goats: 15 Alpine (AG), 13 Saanen (SG) and 8 Anglo-Nubian (ANG) were used to evaluate dry matter intake (DMI), body weight (BW) changes and milk production to validate Wood's model in lactation curves. The kids pre-weaning weight, weaning weight (WW) and daily weight gain (DWG) were determined. Milk production was measured daily for a period of 90 d. The DWG was quantified daily, while BW was recorded weekly. Performance of 48 kids (20 AG, 15 SG and 13 ANG), aged 15 d were evaluated. Wood's model was utilised to describe goat's lactation curve in the different studied goat breeds. Milk production was differed between breeds and according to the number of kids suckled (P < 0.05). Both of DMI and BW showed a linear increase (P < 0.05) during the studied period. Both of WW and DWG were unaffected by type of kidding and breed and were higher in males than in females. It is suggested that equation of Wood's model is adequate to describe the lactation curve in studied goat breeds. The ANG and AG breeds versus SG had more persistence for milk production which was higher for those with single type of birth than those with twins.

A Void Fraction Characterisation by Low Frequency Acoustic Velocity Measurements in Microbubble Clouds

Low frequency acoustic velocity measurements have been applied for the characterization of microbubble clouds generated in water. This method, based on the Wood's model (1941) links the acoustic velocity throughout a two-phase medium to its void fraction value. Low frequency means below resonance frequencies of the bubbles inside the cloud. An original bench was developed to allow the qualification of this method. The experiments conducted allowed us to characterize void fraction values between 10-3 and 10-7. The radii of the studied microbubbles are between a few micrometers and a hundred micrometers.

Vers une psychiatrie cognitive de remédiation sur le modèle de la médecine physique et de réadaptation

The actual but inconstant and partial efficiency of psychoactive drugs long exposed the care model to the issue of rehabilitation and treatment of patient's residual symptoms. However, for the last thirty years, improvement of our theoretical knowledge on psychiatric diseases, as in psychopathology and in pure research, has enabled to think about new therapeutics. Moreover, the Wood's model in physical medicine and rehabilitation gives psychiatry a new model for rehabilitation programs, in which patients’ needs are highly regarded in order for him to get back to an optimum global functioning, and to recover from illness’ trauma. This psychiatric cognitive and rehabilitation model, necessarily multidisciplinary, leads to deep change in psychiatrist's job in treating patients with serious or chronic mental illnesses.

Lactation curves and economic results of Saanen goats fed increasing dietary energy levels obtained by the addition of calcium salts of fatty acids

The objective of this study was to evaluate the use of calcium salts of fatty acids (CSFA) to increase the dietary energy levels for Saanen goats and their effects on the lactation curve, dry matter intake, body weight, and economic results of the goats. Twenty multiparous goats, weighing an average of 63.5±10.3 kg, were randomly assigned to one of four treatment groups, each receiving one of the following dietary energy levels: a control diet consisting of 2.6 Mcal of metabolizable energy per kg of dry matter (Mcal ME/kg DM) or a test diet supplemented with CSFA (Lactoplus®) to obtain 2.7, 2.8, or 2.9 Mcal ME/kg DM. Goats were housed in individual stalls and were fed and milked twice daily. The animals were evaluated until 180 days in milk by measuring dry matter intake and milk yield. These measurements were used to calculate feed efficiencies and the cost-benefit ratio of diet and lactation curves using Wood's nonlinear model. Increasing dietary energy levels showed no effect on body weight. Supplementation with CSFA did not limit dry matter intake; however, it changed the shape of the lactation curve by promoting a late peak lactation with a longer duration. Milk yields at 180 days in milk had a quadratic increase with a maximum energy level at 2.85 Mcal ME/kg DM. Increasing the dietary energy level for Saanen goats using CSFA changes their lactation curves, with the best milk production achieved with a 2.85 Mcal ME/kg DM diet; however, the greatest economic results were obtained with a 2.7 Mcal ME/kg DM diet.

Modeling Metallic Elements Dry Deposition for Daytime and Nighttime Sampling Period at a Traffic Sampling Site

The main purpose of this study was to monitor ambient air particles and metallic elements (Zn, Pb, Mg, and Ca) in total suspended particulates (TSP) concentrations and dry deposition. In addition, the calculated/measured dry depositions flux ratios of ambient air particles and metallic elements (Zn, Pb, Mg, and Ca) were also evaluated using Wood's model at Hung Kuang (traffic) site in Central Taiwan from years 2011 to 2012. The results indicated that: 1) the mean highest concentration for metallic element Zn occurred at 10 μm particle size during the daytime sampling period; 2) the mean highest concentration of metallic elements Mg occurred at 23 μm particle size during the nighttime sampling period; and 3) the mean highest concentration of metallic element Pb occurred at 20 μm particle size for the average sampling time of the daytime and nighttime sampling periods at this traffic sampling site.

Assessing the low frequency acoustic characteristics of Macrocystis pyrifera, Egregia menziessi, and Laminaria solidungula

The acoustic properties of kelp forests are not well known, but are of interest for the development of environmental remote sensing applications. This study examined the low-frequency (0.2-4.5 kHz) acoustic properties of three species of kelp (Macrocystis pyrifera, Egregia menziessi, and Laminaria solidungula) using a one-dimensional acoustic resonator. Acoustic observations and measurements of kelp morphology were then used to test the validity of Wood's multi-phase medium model in describing the acoustic behavior of the kelp. For Macrocystis and Egregia, the two species of kelp possessing pneumatocysts, the change in sound speed was highly dependent on the volume of free air contained in the kelp. The volume of air alone, however, was unable to predict the effective sound speed of the multi-phase medium using a simple two-phase (air + water) form of Wood's model. A separate implementation of this model (frond + water) successfully yielded the acoustic compressibility of the frond structure for each species (Macrocystis = 1.39 ± 0.82 × 10(-8) Pa(-1); Egregia = 2.59 ± 5.75 × 10(-9) Pa(-1); Laminaria = 8.65 ± 8.22 × 10(-9) Pa(-1)). This investigation demonstrates that the acoustic characteristics of kelp are species-specific, biomass-dependent, and differ between species with and without pneumatocyst structures.

Use of Wood's model to analyze the effects of milking methods on lactation curve in sheep

One hundred and sixty-six lactating Makui breed sheeps (2–6 years old) were used to investigate the effects of two milking methods (milking with oxytocin (OT) and milking without oxytocin (HT)), ewes age and stage of lactation on milk yield and composition during 168 days of lactation and to estimate shape of lactation curve using Wood's model. Oxytocin treatment (OT) had a significant effect on the average daily milk yield (ADMY) and total milk yield (TMY) (P<0.0001). TMY for OT ewes was 45.61% (P<0.01) greater than that in HT ewes. OT ewes had significantly (P<0.01) longer lactation period (LL) than HT ewes. The effects of ewes age on ADMY, TMY and LL were significant (P<0.01). In both milking methods, 4-, 5- and 6-year-old ewes produced significantly (P<0.01) greater ADMY and TMY than 2 years old ones. Stages of lactation had a highly significant (P<0.0001) effect on milk yield. Except (b) parameter, (a) and (c) parameters of Wood's model were significantly (P<0.05) affected by milk measurement methods. In addition, effects of ewes age on the model's parameters were significant (P<0.05). TMY obtained by Wood's model was not affected (P>0.05) whereas peak time (PT), peak yield (PY) and persistency (P) were significant (P<0.05) as compared with Fleischmann method for two milking methods. OT ewes reached PT (day) earlier than HT ewes. OT method had a significant effect on fat and SNF percent (P<0.05) whereas percent of protein and lactose unaffected by OT and HT methods (P>0.05). In both methods, stages of lactation had a highly significant effect on milk fat, protein and SNF percentage (P<0.05). The results of this experiment showed that oxytocin has galactopoietic effect due to the contraction of myoepithelial cells maybe limiting the effects of milk-borne negative feed-back mechanism on milk secretion and Wood's model overestimated TMY and PY whereas underpredicted PT and P.

Syn-eruptive morphometric variability of monogenetic scoria cones

According to Wood's model, morphometric parameters such as slope angle can provide valuable information about the age of conical volcanic edifices such as scoria cones assuming that their initial slopes range from 30° to 33°, measured manually on topographic maps, and assuming that their inner architectures are homogenous. This study examines the morphometric variability of nine young (a few thousand years old) small-volume scoria cones from Tenerife, Canary Islands, using high-resolution digital elevation models in order to assess their slope angle variability. Because of the young age and minimal development of gullies on the flanks, their morphometric variability can be interpreted as the result of syn-eruptive processes including: (1) pre-eruptive surface inclination, (2) vent migration and lava outflow with associated crater breaching and (3) diversity of pyroclastic rocks accumulated in the flanks of these volcanic edifices. Results show that slope angles for flank sectors differ by up to 12° among the studied volcanoes, which formed over the same period of time; this range greatly exceeds the 2–3° indicated by Wood. The greater than expected original slope range suggests that use of morphometric data in terms of morphometry-based relative dating and detection of erosional processes and settings must be done with great care (or detailed knowledge about absolute ages and eruption history), especially in field-scale morphometric investigation.