Low Production Groups Research Articles

Individualised feeding of concentrate supplement according to milk yield did not increase milk production in pasture-grazed cows near peak lactation

ABSTRACT In grazing systems, feeds other than pasture are often used to increase dry matter intake and milk production. The study aimed to evaluate the effect of individually feeding pasture-grazed dairy cows near peak lactation based on their individualised milk production compared with a flat-rate feeding regime. All cows in the flat-rate treatment were offered 4 kg wet weight (3.6 kg DM) of concentrate/d. In the individualised feeding treatment, cows were offered 6, 4, and 2 kg wet weight/d (5.4, 3.6 and 1.8 kg DM/d) in the high, moderate, and low production groups, respectively. Individualised feeding of concentrates based on cow milk production did not alter milk or milk component yield at a herd level, but increased milk yield and tended to increase yield of fat, protein, and lactose in cows in the medium milk yield tertile. Individualised feeding reduced milk protein yield in cows in the low milk yield tertile, compared with flat rate feeding. The results do not support individualised feeding in grazing dairy systems where the maximum level of concentrate offered/ is ≤ 6 kg DM/d and milk production/cow ≤30 kg milk/d or ≤2.5 kg fat and protein/d.

Dynamic Expression Profile of Follicles at Different Stages in High- and Low-Production Laying Hens.

Improving the efficiency of hens and extending the egg-laying cycle require maintaining high egg production in the later stages. The ovarian follicles, as the primary functional units for ovarian development and oocyte maturation, play a crucial role in regulating the continuous ovulation of hens. The egg production rate of laying hens is mostly affected by proper follicle growth and ovulation in the ovaries. The objective of this study was to identify the key genes and signaling pathways involved in the development of ovarian follicles in Taihang hens through transcriptome screening. In this study, RNA sequencing was used to compare and analyze the transcriptomes of ovarian follicles at four developmental stages: small white follicles (SWF), small yellow follicles (SYF), F5 follicles, and F2 follicles, from two groups: the high continual production group (H-Group) and the low continual production group (L-Group). A total of 24 cDNA libraries were constructed, and significant differential expression of 96, 199, 591, and 314 mRNAs was detected in the SWF, SYF, F5, and F2 follicles of the H and L groups, respectively. Based on the results of GO and KEGG enrichment analyses, each stage of follicle growth possesses distinct molecular genetic features, which have important effects on follicle development and significantly promote the formation of continuous production traits through the biosynthesis of steroid hormones, cytokine-cytokine receptor interaction, and neuroactive ligand-receptor interaction. Additionally, through STEM analysis, we identified 59 DEGs, including ZP4, KCNH1, IGFs, HMGA2, and CDH1, potentially associated with follicular development within four significant modules. This study represents the first transcriptome investigation of follicles in hens with high and low egg-producing characteristics at four crucial developmental stages. These findings provide important molecular evidence for understanding the regulation of follicular development and its variations.

FarmDain, a Decision Support System for Dairy Sheep and Goat Production.

Managing a milk zone in the dairy industry is demanding. Data necessary for efficient management are difficult to acquire because they usually must be collected in organized and standardized ways. On the other hand, software practices constantly provide new tools that can go beyond simple record-keeping practices and add value to the data. In this work, FarmDain is a novel web-based application for sheep and goat management. It aims to improve milk production and processing by digitizing the value chain in data acquisition, processing and visualization between dairy production businesses and their milk suppliers. FarmDain uses state-of-the-art software technologies to model the data collection process and provides a straightforward user interface to facilitate data processing and visualization. Using the app in a case study carried out for 12 months in a dairy sheep farm resulted in lower feeding cost per milked ewe by 5.5% when ewes were allocated into high and low milk production groups compared to the scenario of remaining in one single group. Furthermore, based on reports provided by the app, culling and genetic selection decisions were made to improve the overall farm performance. Similar practices were applied in all farms optimizing their productivity, which led to increased profitability for farms and the Dairy Factory.

Role of SNPs located in the exon 9 of ATAPA1 gene on goose egg production

The meat and egg of goose is one of the main components of human food supply. The improvement of goose egg production is particularly important for the increasing human population. However, limited information is available about the effective molecular markers and mechanisms of egg production in goose. In this study, we jointly utilized the data of genome resequencing in different egg production Sichuan white goose and transcriptome at different follicle development stages to identified the molecular markers and mechanisms of egg production. The coefficient of variation of individual egg production in Sichuan white goose population is 0.42 to 0.49. Fifty individuals with the highest (laying 365 days egg number, LEN365=79-145) and 50 individuals with the lowest (LEN365=8-48) egg production were divided into high and low egg production groups. Based on whole-genome sequencing data of the selected samples, 36 SNPs (annotation novel.12.470, CELF2, ATP1A1, KCNJ6, RAB4A, UST, REV3L, DHX15, CAVN2, SLC5A9, Cldn5, MRPS23, and Tspan2) associated with the LEN365 were identified, involving multiple pathways such as metabolism and endocrinology. Notably, 5 SNPs located in the exon9 of ATP1A1 were identified by GWAS analysis. The association analysis with LEN365 showed the phenotypic variance explained of this haplotype consisting of 5 SNPs is 20.51%. Through transcriptome data analysis, we found the expression of ATP1A1 in the granular layers was increased in the stage of small yellow follicle to large yellow follicle (LYF) and LYF to F5, while decreased in F2 to F1. For the first time, we report the haplotype region formed by 5 SNPS on exon9 of ATP1A1 is associated with egg production in goose and involved in follicle selection and maturation processes.

Integrating genome-wide methylation and transcriptome-wide analyses to reveal the genetic mechanism of milk traits in Kazakh horses

Horse Milk has important quantitative characteristics and high economic value. However, the DNA methylation regulators involved in horse milk traits have not been clarified. To explore the important role of genome-wide DNA methylation in regulating equine milk yield, this study systematically investigated the genome-wide DNA methylation profiles of Kazakh horse blood by comparing a high-production group (HP, average daily milk yield of 7.5 kg) and low-production group (LP, average daily milk yield of 3.2 kg) using deep whole-genome bisulfite sequencing. First, both groups showed similar proportions of methylation at CpG sites. Subsequently, we identified 26,677 differential methylated regions (DMRs) of CG, 15 DMRs of CHG, 480 DMRs of CHH and 8268 DMR-related genes (DMGs). GO and KEGG analyses revealed that some DMGs were involved in regulating milk and milk component formation. By combining the WGBS-seq and the previous RNA-seq data, a total of 94 overlapping genes were obtained. Finally, we found that 9 DMGs are likely involved in milk production by Kazakh horses.

Peripheral blood mononuclear cell mitochondrial enzyme activity is associated with parity and lactation performance in early lactation Holstein dairy cows

Mitochondria are central to metabolism and are the primary energy producers for all biosynthesis, including lactation. The objectives of this study were to determine if high- and low-producing dairy cows exhibit differences in peripheral blood mononuclear cell mitochondrial enzyme activities of citrate synthase, complex I, complex IV, and complex V during early lactation and, thus, to determine whether those differences were related to differences in lactation performance in the dairy cow. Fifty-six Holstein cows were assigned to 1 of 4 groups: (1) primiparous high, (2) primiparous low, (3) multiparous high, or (4) multiparous low. Primiparous and multiparous cows were analyzed separately. Then, cows were divided into high or low production groups for each production parameter [peak milk, average milk, energy-corrected milk (ECM), fat-corrected milk (FCM), milk lactose, milk fat, milk protein, total solids (TS), solids-not-fat, feed efficiency, and somatic cell count (SCC)]. For all data analysis, production parameters are expressed as yields (kg/d) and SCC (103 cells/mL). High and low production groups were defined by their respective mean production parameters for the 56 cows, with below average cows defined as low and above average cows defined as high. Whole blood samples were collected at one time point, approximately 70 d in milk at 0800 h, and processed for crude mitochondrial extracts from peripheral blood mononuclear cells to determine the activity rates of mitochondrial enzymes. Milk samples were collected 9 times (3 d, 3 times per d) during the week of blood collection and analyzed for major components (fat, protein, lactose, TS, and SCC). Multiparous cows had lower citrate synthase activity than primiparous cows across all production parameters. High-producing cows had greater complex I activity for peak milk, milk yield, ECM, FCM, milk fat, TS, and feed efficiency, and greater complex V activity for ECM, FCM, milk lactose, milk fat, and TS across parities. These findings imply that the most influential respiratory chain enzymes on the level of milk production are those responsible for electron transport chain initialization and ATP production.

The real potential of semen production of Bali Bull: over year observation at Singosari National Artificial Insemination Center (SNAIC), Singosari-Indonesia

Increased reproduction is closely related to increased bull productivity. The high productivity of these bulls will increase the amount of straw. The productivity capability of Bali bull is essential in producing straw. High productivity will result in high straw production as well. So the research aims to determine the productivity of Bali bull at SNAIC in the last year. 31 Bali bulls aged 4 – 11 years were used in this study at SNAIC. Total 1.273 ejaculations collection from these during one year. The parameters used in this study include the number of successful holding of each bull, total productivity, and estimation of straw production in one year. From 31 Bali Bulls, the ranking was grouped into two based on values of sperm productivity. The two groups were analyzed using an unpaired T-test. The results showed that the pH, volume, individual motility, concentration, and abnormality were significantly different (P < 0.05) between the high and low groups. The percentage of successful shelters, total TSM, and the number of straws produced in one year in the high productivity group were higher than the low productivity group. High productivity groups are the best with high productivity potential and potential as a source of semen.

Productivity curve and social network analysis in science megaproject management

Megaprojects aimed at delivering next-generation, multi-billion euro scientific research facilities are complex and high-risk endeavours, requiring expert knowledge spanning a wide spectrum of technical and administrative fields. Such organisations tend to evolve organically, responding to technical and political challenges. They are almost certain to fail to meet expectations on schedule, budget, and deliverables. Whilst there have been illuminating ‘top-down’ phenomenological megaproject studies recently, this article reports a ‘bottom-up’ perspective on the emergence of these issues. Firstly, the staff productivity distribution curves are analysed at a European science megaproject, and a stratified culture is identified: there is a small, high productivity ‘clique’, and a vast, low-productivity group of ‘outsiders’ operating at only 50% of their potential. The social network is then analysed, revealing a dense decision-making group that is only tenuously connected to technical expert teams via hierarchy. Staff inefficiency is linked to superfluous roles in middle management, carrying increased bureaucratic burdens and a financial loss ∼10% of the annual salary budget. Corrective suggestions are given, for the current megaproject and future activities to mitigate these causes. This should help to reduce some of the overspend, schedule overrun, and reductions in ambition and scope that have become megaproject norms.

Plasma Hydrogen Sulfide Is Positively Associated With Post-operative Survival in Patients Undergoing Surgical Revascularization.

Objective: Hydrogen sulfide (H2S) is a gaseous signaling molecule and redox factor important for cardiovascular function. Deficiencies in its production or bioavailability are implicated in atherosclerotic disease. However, it is unknown if circulating H2S levels differ between vasculopaths and healthy individuals, and if so, whether H2S measurements can be used to predict surgical outcomes. Here, we examined: (1) Plasma H2S levels in patients undergoing vascular surgery and compared these to healthy controls, and (2) the association between H2S levels and mortality in a cohort of patients undergoing surgical revascularization.Methods: One hundred and fifteen patients undergoing carotid endarterectomy, open lower extremity revascularization or lower leg amputation were enrolled at a single institution. Peripheral blood was also collected from a matched control cohort of 20 patients without peripheral or coronary artery disease. Plasma H2S production capacity and sulfide concentration were measured using the lead acetate and monobromobimane methods, respectively.Results: Plasma H2S production capacity and plasma sulfide concentrations were reduced in patients with PAD (p < 0.001, p = 0.013, respectively). Patients that underwent surgical revascularization were divided into high vs. low H2S production capacity groups by median split. Patients in the low H2S production group had increased probability of mortality (p = 0.003). This association was robust to correction for potentially confounding variables using Cox proportional hazard models.Conclusion: Circulating H2S levels were lower in patients with atherosclerotic disease. Patients undergoing surgical revascularization with lower H2S production capacity, but not sulfide concentrations, had increased probability of mortality within 36 months post-surgery. This work provides insight on the role H2S plays as a diagnostic and potential therapeutic for cardiovascular disease.

Understanding the dairy production systems in rural settlements in the Brazilian semi-arid region: characterization, typology, and holistic perception.

The objective of this study was to characterize and typify dairy farms and to evaluate society's perception of dairy production in rural settlements in the Brazilian semi-arid region. A questionnaire containing questions related to socioeconomic, livestock, physical, herd management, and production indicators was applied to 17 milk farmers for typological analysis. A second questionnaire was subsequently applied to the same 17 farmers for the holistic perception of dairy farming in rural settlements, in addition to 47 technicians in the area of animal science and 140 laypeople. Milk samples were collected in the settlement's community cooling tank, while the water used for milking management was collected in the milking parlor at the 17 farms. Multivariate analysis techniques and thematic analysis were performed. Three dairy production systems were identified: low production group (0-25 L), medium production group (25-50 L), and high production group (50-100 L). The physicochemical properties (composition, density, and cryoscopy) of milk attended the Brazilian regulation values. The microbiological parameters of milk and water used for milking are at odds with regulations. Regarding the typology, the indicators, livestock, and productivity showed discriminatory power (P < 0.05) between the productive systems. The responses from the segments of society showed different views on dairy production in rural settlements. It is concluded that the dairy farmers have low education and the cleaning product and water used in milking are out of regulation. The livestock and production indicators typified mainly dairy farms, while the holistic perception showed a lack of efficiency in rural extension, ignorance of the potential of the productive system. Finally, the creation of public policies focusing on the development of the milk production system in settlements is recommended.

Transcriptome analysis of ovary tissues from low- and high-yielding Changshun green-shell laying hens

BackgroundChangshun green-shell laying hens are unique to Guizhou Province, China, and have high egg quality. Improving egg production performance has become an important breeding task, and in recent years, the development of high-throughput sequencing technology provides a fast and exact method for genetic selection. Therefore, we aimed to use this technology to analyze the differences between the ovarian mRNA transcriptome of low and high-yield Changshun green-shell layer hens, identify critical pathways and candidate genes involved in controlling the egg production rate, and provide basic data for layer breeding.ResultsThe egg production rates of the low egg production group (LP) and the high egg production group (HP) were 68.00 ± 5.56 % and 93.67 ± 7.09 %, with significant differences between the groups (p < 0.01). Moreover, the egg weight, shell thickness, strength and layer weight of the LP were significantly greater than those of the HP (p < 0.05). More than 41 million clean reads per sample were obtained, and more than 90 % of the clean reads were mapped to the Gallus gallus genome. Further analysis identified 142 differentially expressed genes (DEGs), and among them, 55 were upregulated and 87 were downregulated in the ovaries. KEGG pathway enrichment analysis identified 9 significantly enriched pathways, with the neuroactive ligand-receptor interaction pathway being the most enriched. GO enrichment analysis indicated that the GO term transmembrane receptor protein tyrosine kinase activity, and the DEGs identified in this GO term, including PRLR, NRP1, IL15, BANK1, NTRK1, CCK, and HGF may be associated with crucial roles in the regulation of egg production.ConclusionsThe above-mentioned DEGs may be relevant for the molecular breeding of Changshun green-shell laying hens. Moreover, enrichment analysis indicated that the neuroactive ligand-receptor interaction pathway and receptor protein tyrosine kinases may play crucial roles in the regulation of ovarian function and egg production.

Genetic, biological and economic evaluation of sweet potato accessions in the collection of the Plant Introduction and Acclimatization Department, Udmurt FRC, UB RAS

An important area of crop development is the introduction of new vegetable plants, one of which is the sweet potato Ipomoea batatas (L.) Lam. The aim of our research was genetic, biological and economic assessment of sweet potato accessions held in the collection of the Plant Introduction and Acclimatization Dept., Udmurt Federal Research Center, Ural Branch of the RAS (UdmFRC UB RAS).Within this experiment, DNA polymorphism of 16 accessions of I. batatas was tested using ISSR markers. All accessions were found to represent different genotypes; the VM 17 accession obtained as a result of a bud mutation differed significantly from the original accession in its genotype.Evaluation of 16 accessions of sweet potato cultivars was carried out in a small-plot field experiment. The results of biological and economic assessment witnessed to the prospects of sweet potato cultivation within the territory of the Udmurt Republic for marketable tuber production. The productivity of the accessions was 140–2700 g of tubers per plant. According to their productivity, the accessions were divided into clusters: the low-productivity group (up to 500 g), with ‘Betty’, Fioletovy, ‘Beauregard’, ‘Covington’ and Bezhevy; medium-productivity group (500–1000 g), with ‘Jewel’, Fioletovy Sochi, Brazilsky, Afgansky, Vinnitsky rozovy, Lyubitelsky and ‘Bayou Bell’; and high-productivity group (more than 1000 g), with Pobeda 100, ВM 17, Druzhkovsky and Bely NBS. On the basis of the evaluation, 11 sweet potato accessions were recommended for cultivation in the Middle Urals: Afgansky, ‘Bayou Bell’, Bely NBS, ВM 17, Brazilsky, Druzhkovsky, Fioletovy Sochi, ‘Jewel’, Lyubitelsky, Pobeda 100, and Vinnitsky rozovy.

Assessment of expected genetic gain in average daily milk yield in different milk productivity groups on simulating selection intensity in Sahiwal cattle

Data on first lactation milk productivity (milk yield per day of 305 days or less lactation length) records of Sahiwal cattle maintained at an organized herd of ICAR-National Dairy Research Institute, Karnal, Haryana, India were utilized. Records (386) of Sahiwal animals spread over a period of 29 years (1988–2016) were categorized into groups, viz. low (3–5 kg), medium (&gt;5–8 kg) and high (&gt;8 kg) based on the milk productivity level. Expected genetic gain (ΔG)/generation in different productivity groups at different levels of intensity of selection was estimated using intensity of selection (i), phenotypic standard deviation (sp) and heritability (h2) of the trait. The expected genetic gain/generation obtained was divided by generation interval to get genetic gain/year. The overall average first lactation milk yield/day of 305 days or less lactation length (MY/LL) in Sahiwal cattle was observed as 6.61 kg/day. Heritability estimate of first lactation MY/ LL was 0.36. Average first lactation 305 days milk yield (305 DMY) of low, medium and high milk productivity groups was 941.21, 1810.34 and 2734.14 kg, respectively. The generation interval in Sahiwal cattle was estimated as 5.31 years. Results showed that when the proportion of animals selected was less, i.e. at higher selection intensities, a higher genetic gain was obtained. There was more change in expected ΔG/year while shifting from low milk productivity group to medium productivity group but there was very less improvement in the expected ΔG from medium to high productivity group at different levels of selection intensities.

Differences in methane production, yield and intensity and its effects on metabolism of dairy heifers

The effects of divergent phenotypic classification in crossbreed Holstein × Gyr dairy heifers for methane emissions in relation to performance, digestibility, energy and nitrogen partition, blood metabolites and temperature of body surface were evaluated. Thirty-five heifers were classified as high and low emission for CH4 production (g/day), yield (g/kg dry matter intake) and intensity (g/kg average daily gain). Digestibility was evaluated by total collection of feces and urine. Gas exchanges were obtained in open-circuit respiratory chambers. A completely randomized design was used and divergent groups were compared by Fisher's test. No differences were found in intake traits between groups of CH4 production and intensity. The low yield group had higher intake. For digestibility and temperature at different body sites were no differences between variables. High production group had higher energy losses as methane and heat production. Low intensity group had higher digestible energy, energy balance and ratio between metabolizable and digestible energy. Urinary nitrogen was 14.3% lower for low production group. There was a difference between methane yield divergent groups for nitrogen intake, digestible and retained. Energy and nitrogen partitioning traits are correlated to the animals divergent for methane production and yield. The low production group presented lower blood insulin concentration. It was not possible to identify divergent animals for CH4 emission using the infrared thermography technique.

Melatonin concentration in cow’s milk and sources of its variation

ABSTRACT The effects of weather/season (winter and summer), milk production (high and low), and milking time (night and day) on melatonin levels were evaluated. The melatonin in the milk from 30 individual cows, the bulk tank milk (BTM) from 16 farms, and ultra-high temperature (UHT) processed milk of 12 brands over two seasons were also assessed. The melatonin average concentration was 6.98 pg/mL in the cows’ milk, 4.71 pg/mL in the BTM, and 5.62 pg/mL in the UHT milk. In the night milk, the melatonin concentration averaged 14.87 pg/mL, whereas it was 6.98 pg/mL in the total daily milk. In winter, the milk melatonin concentration was, on average, 74.7% higher than in the summer (13.89 vs. 7.95 pg/mL). The night milk from the low production group in winter also had a higher concentration of melatonin (41.94 pg/mL). The variables related to illuminance, such as the time of milking and season of the year, had considerable effects on the melatonin concentration in milk. Collecting and marketing melatonin-rich milk could benefit populations and agribusiness.

Molecular characterization, alternative splicing and expression analysis of ACSF2 and its correlation with egg-laying performance in geese.

ACSF2 (encoded by acyl-CoA synthetase family member 2) belongs to the acyl-CoA synthetase (ACS) family, activating fatty acids by forming a thioester bond with CoA. In our previous study, a SNP residing in the intron of ACSF2 was identified to be linked to goose egg-laying performance. But the structure of goose ACSF2 as well as its role in reproduction remains unknown. In this study, we cloned and characterized ACSF2 in Yangzhou geese. A total of four alternative splice variants, designated as ACSF2-1, ACSF2-2, ACSF2-3 and ACSF2-4 respectively, were identified in the ovary. The coding regions of the four variants are 1770, 1692, 1599 and 1917bp in length, respectively encoding 589, 563, 532 and 638 amino acids with conserved AMP-binding sites. All ACSF2 variants were widely expressed in 11 tested tissues in geese, except that the ACSF2-2 transcript was not detected in hypothalamus, pituitary gland and granulosa cells. Subcellular localization revealed that ACSF2 is a mitochondrial matrix protein. ACSF2 mRNA level was compared between high egg production (HEP; n=8) and low egg production (LEP; n=10) groups and showed a lower (P<0.05) mRNA level in the HEP group. Further experiments indicated that overexpressing ACSF2 resulted in a significant increase of caspase-3 mRNA levels and that ACSF2 knockdown triggered a decrease in the caspase-3 mRNA level in granulosa cells. Similarly, the lower caspase-3 mRNA levels were identified in ovaries of the HEP group with lower ACSF2 mRNA levels. The research showed that the ACSF2 mRNA levels had a positive correlation with caspase-3 mRNA levels invivo (R=0.86, P<0.01). Our results suggest that lower ACSF2 expression promotes the laying performance of goose possibly by inhibiting granulosa cell apoptosis and facilitating follicular development.

국내 Holstein종 젖소의 생산수준이 젖소의 수익형질에 미치는 효과

Data including 1,372,050 milk records pertaining to 438,019 cows from 1983 to 2011 collected during performance tests conducted by the National Livestock Cooperative Dairy Improvement Center were used to calculate milk income and profit of individuals and investigate the effects of production levels of early lactation (parity 1 and 2, respectively). Individuals with a moderate level of early lactation stayed longer in herds. Among parity 1, the 9,000 kg or higher group had a lower mean number of lactations than the overall mean of 3.13. The 7,000 kg or lower and 10,000 kg or higher groups had lower mean life time milking days than the overall mean of 1,076.8 days. Standard deviations of lifetime traits tended to decrease as production levels increased. For parity 2, the 11,000 kg or higher group had a lower mean number of lactation than the overall mean of 3.43. The lifetime milking days was highest in the 12,000 kg group (1,212.0 days), and generally smaller in the lower groups. Profit increased as the production level of groups increased for both parity 1 and 2. In groups with low production levels, profit of parity 1 was higher than that of parity 2, while the reverse was true in groups with high production levels. These results suggest that individuals in the low production groups had a greater likelihood to be culled due to reproductive or other problems. Furthermore, the accuracy of the prediction of lifetime profit of individuals with a milk yield of 305 days seems to be higher for parity 2 than parity 1; therefore, it is desirable to predict lifetime profit using the 305d milk yield of parity 2. In conclusion, breeding goals are based on many factors in functions for the estimation of profit; however, production levels during early lactation (parity 1 and 2) can be used as indicators of profit to extend profitability.

Selection of models of lactation curves to use in milk production simulation systems

The objective of this study was to select models of lactation curves with a better adjustment to the observed data in models of milk production simulation systems. A data base on 6,459 recordings of daily milk production was used. These data were obtained from monthly and fortnightly controls of milk between 2004 and 2007, from 472 lactations of animals from ten different milking cow herd farms. Based on rolling averages of milk production (MP-L/day) per cow, the ten herd farms were divided into low (L &lt; 15), medium (15 &lt;M &lt; 20) and high (H &gt; 20). Data were also divided according to the lactation numbers in first, second, third or greater. Eight lactation curve models commonly used in literature were compared. The models were individually adjusted for each lactation. The goodness of fit used for comparison of those models was the coefficient of determination, mean square error, mean square prediction error and the Bayesian information criterion. The values for the goodness of fit obtained in each model were compared by using 95% probability confidence interval. Wilmink (1987) model showed a better adjustment for cows of the first lactation numbers, whereas the Wood (1967) model showed a better adjustment for cows of the third or greater lactations numbers for the low milk production groups. Wood model showed a better adjustment for all the lactation numbers for the medium milk production group. Dijkstra (1997) model showed a better adjustment for all lactation numbers for the high milk production group. Despite of being more recent, the model by Pollott (2000), mechanist based and with a higher number of parameters, showed a good convergence for the used data.

Testing and validation of DRIS for apple tree

To evaluate three procedures of the calculation of DRIS indices, as well as the efficiency of DRIS as a method for the interpretation of apple tree leaf analyses. This study uses data collected in apple producing areas of the Rio Grande do Sul and Santa Catarina States, Brazil. The concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, boron, copper, iron, manganese, and zinc were determined in the leaf samples. The validation of the DRIS method used results of an experiment of potassium fertilization. The DRIS indices were calculated using two criteria for the choice of the ratio order of nutrients (F value ratio of variance of the relationships among nutrients between the reference group and the low productivity group, and R value - correlation coefficients between the productivity and the relationship between pairs of nutrients) and three forms of calculation of nutrient functions (methods of Beaufils, Jones and Elwali &amp; Gascho). The Nutritional Balance Index (NBI) presented negative correlation with the productivity in all combinations. The DRIS method described by Elwali &amp; Gascho, using the F value, presented a performance similar to the criterion of sufficiency range, and it can be used for the interpretation of foliar analysis of apple trees, because it presents values of the nutritional balance index that indicates the nutritional status of the plants, and for the efficiency in the nutritional diagnosis of the crop.

DRIS norms for evaluating the nutritional state of apple tree

For Brazilian conditions there are still no studies on the use of the diagnosis and recommendation of the integrated system (DRIS) for nutritional diagnosis of the apple tree. The nutritional diagnosis of the apple tree is made using the criterion of sufficiency range. The aim of this report is to establish DRIS norms to interpret the results of apple tree leaf analysis in South Brazil. The study covered the apple producing areas of the states of Rio Grande do Sul and Santa Catarina, in 70 orchards selected for their high productivity and employment of excellent management techniques. The concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, boron, copper, iron, manganese, and zinc were determined in leaf samples. DRIS indices were calculated using two criteria for the choice of the ratio order of nutrients (F value - ratio of the variance of the relationships among nutrients between the reference group and the low productivity group, and R value - correlation coefficients between the productivity values and the relationship between pairs of nutrients) and three forms to calculate the nutrient functions (methods of Beaufils, Jones and Elwali &amp; Gascho). The two criteria for the choice of the ratio order of the nutrients selected different ratios. The concentrations of nutrients presented positive correlations (P &lt; 0.01) with the respective indices DRIS, except for N. The defined DRIS norms are applicable for the nutritional diagnosis of apple trees.