s. h. farhangfar

In many countries of the world, the camel has played an important role in the lives of people in arid and semi-arid regions in terms of providing milk and meat products. Based on phenotypic characteristics, the camel has been adapted to the deserts from physiological, anatomical, and behavioral points of view. Due to limited water resources, the south Khorasan province of Iran has not been an appropriate geographical region for a great number of agricultural products. Weighing plays an important role in the management of camel breeding to adjust the nutritional needs and also the annual evaluation of the animals. One of the main challenges of camel breeding is the difficulty of recording and the lack of records due to the wild nature and also the large size, especially in adults. Due to the many difficulties and risks, camel breeders usually use various potential alternative tools such as apparent estimation or weighing tape to estimate the weight of camels at different ages. For farm animals, significant correlations between body measurements and body weight can be used as a tool to estimate the weight of animals through a mathematical equation. The main objective of this study was to compare the accuracy of artificial neural network (ANN) and multiple linear regression model (MLR) in estimating the body weight of a humped camel.
In the present study, the data of a total number of 177 one-humped camels in four groups  (including 1. 63 adult female Pakistani camels aged between 9 and 12 years, 2. 21 adult female Baluchi camels aged between 9 and 12 years, 3. 93 male and female camels less than 2 years of age of Pakistani and Baluchi breeds, and 4. total camels) collected at the South Khorasan camel breeding station in 2019 were used. Morphological characteristics of camels include: neck length, neck girth, hand length, foot length, shoulder height to the ground, hump height to the ground, hip height to the ground, chest girth, chest width, abdomen girth, hip width, tail length, breast height, and breast girth were measured. After measuring the body dimensions, the evaluated camels were weighed using a 1000 kg digital scale. To estimate the weight of camels from their body dimensions, the data were analyzed using the MLR model and ANN with the nnet package in R software. For ANN analysis, 80% of the data were considered for network training and 20% for testing. The accuracy of MLR and ANN for camel body weight estimation was compared using the coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE).
The results of the MLR model showed that body dimensions of shoulder height to the ground, chest girth, abdominal girth, neck girth, and hand length had a significant effect on body weight (P<0.05). In the ANN model, chest girth, abdominal girth, and shoulder height to the ground were the most important variables in estimating the body weight of camels of the whole population. The MLR and ANN models had acceptable accuracy in weight estimation. However, compared to the MLR model, the ANN model had a higher R2 and a lower error in estimating the weight of camels. In the first group, R2 and RMSE were found to be 0.996 and 6.852, respectively, for ANN while the corresponding values were 0.979 and 22.955, respectively, for MLR.  In the second group, R2 and RMSE were found to be 0.995 and 3.525, respectively, for ANN while the corresponding values were 0.989 and 5.377, respectively, for MLR.  In the third group, R2 and RMSE were found to be 0.896 and 13.959, respectively, for ANN while the corresponding values were 0.849 and 17.549, respectively, for MLR. In the fourth group, R2 and RMSE were found to be 0.929 and 20.248, respectively, for ANN while the corresponding values were 0.903 and 38.505, respectively, for MLR. The results showed that ANN is more accurate compared to MLR in predicting the body weight of camels. 
In terms of goodness of fit (including R2 and RMSE), the results of the present research suggest that both MLR and ANN methods have high acceptable accuracy for predicting body weight in camels. ANN was more suitable compared to MLR, suggesting that it could be used to predict camel body weight. Furthermore, grouping the camels by age and breed could also lead to higher precision and lower prediction error.

 In dairy cows, milk yield changes over the lactation period. Lactation curve modelling could be of importance from nutritional management and genetic selection point of view. The trajectory shape of the lactation curve has inclining and declining slopes which determine total amount of milk yield during the lactation. A great number of linear and nonlinear mathematical models have been so far utilized to describe the shape of the lactation curve in dairy cows. Among the models, mechanistic functions are considered to be more accurate than empirical models in terms of taking account of biological mechanisms undertaken in mammary gland to produce milk. To our knowledge, no research has been carried out to use a complex mechanistic model for describing the lactation curve of Iranian dairy cows. Based on this, the present research aimed to apply a five-parameter nonlinear mechanistic model for mathematical description of the shape of the lactation curve in Iranian first-parity dairy cows.

Animal Breeding Centre of Iran provided the data used in this research. Initial data in separate files were merged and edited by the SPSS software. Final data comprised 5596039 milk test day records from 821153 first-parity cows distributed in 579 herds of 26 provinces over the country. The cows were the progeny of 7957 sires and 530394 dams and calved between 1996 and 2020. The cows were categorized into two groups based on the age of first calving: <=25 or >25 months. Also, two groups of cows were created based on the proportion of Holstein gene inheritance: <100% (grade cows) or 100% (pure Holstein cows). A five-parameter nonlinear mechanistic model was applied to mathematically describe the shape of the lactation curve. The fitted mechanistic model had five parameters including MSmax (maximum milk secretion potential of the lactation), GR (relative proliferation rate of secretory cell number during early lactation), MSLmax (maximum secretion loss), NOD (proportion of parenchyma cell dead at parturition), and DR (relative decline rate in cell number) which their estimates were obtained for different seasons and ages of calving, as well as different genotypes (grade and pure Holstein) using NLIN procedure of the SAS software. Based on the estimated parameters of the model in each year of calving, phenotypic trends were calculated using the SPSS software.

The results indicated that Iranian first-parity dairy cows reach to peak of milk production during the third month of the lactation curve. Based on standard deviation as well as coefficient of variation (CV) of milk test day milk records, maximum variation was observed in the last month of the lactation period. The findings also indicated that cows calved in autumn had the greatest MSmax and GR while cows calved in spring and summer had the lowest magnitude for these parameters (P<0.05). The minimum magnitude of MSLmax and NOD were detected for the cows calved in summer (P<0.05). Regarding the DR parameter of the model, cows calved in spring were observed to have a minimum value. Maximum MSmax, Gr, and DR values ​​were determined for cows calving up to 25 months of age, while maximum MSLmax and NOD values ​​were observed for cows of later ages (P<0.05). Compared to pure Holstein cows, grade cows had higher MSLmax and NOD values, but other parameters were found to be greater in the pure Holstein cows (P<0.05), suggesting that the maximum milk secretion potential during lactation in pure Holstein cows is expected to be higher than that of grade cows. Annual phenotypic change trends were found to be 0.376 kg/year (R2=0.9), 0.00009869 (R2=071), -0.146 kg/year (R2=0.59), -0.011 (R2=0.85), and 0.001 (R2=0.85) for MSmax, GR, MSLmax, NOD, and DR, respectively (P<0.0001).     

This study found that the parameters of the mechanistic model fitted to the milk test day records of Iranian primiparous dairy cows are significantly influenced by the age and season of calving as well as the genotype of the cow. Cows calving in summer are expected to have more persistency. Moreover, pure Holsteins are more persistent than grade cows. Positive and negative annual trends have been detected for MSmax and MSLmax parameters, respectively, during 1996-2020 indicating a favorable increase in maximum milk secretion potential of the lactation and also a favorable decrease in maximum secretion loss over that period.

In dairy cattle enterprise, there are several economic traits associated with productive and reproductive performance which milk yield is the main source of income for the herd keeper. Knowledge of lactation is considered a useful tool for management decision-making. Based on this, lactation curve modeling can be utilized as an appropriate guide for planning nutrition programs as well as genetic selection schemes. So far, main research has been focused on using raw (unadjusted) milk test day records to model the shape of the lactation curve by applying a variety of linear and non-linear mathematical models and a few research have been carried out to use adjusted milk test day records in terms of fat and protein percentages. The main objective of the present research was to compare lactation curve parameters of Iranian first-parity dairy cows among three types of milk test day records including raw milk (RM), fat-corrected milk (FCM), and energy-corrected milk (ECM).

The initial data set was provided by the Animal Breeding Center and Promotion of Animal Products of Iran. Editing of the data was carried out by FOXPRO and Excel software based on some criteria such as age at first calving (was set to be in the range of 18-48 months), minimum (3 kg), and maximum (99.9 kg) of RM. There were a minimum of five test day records for each cow during the lactation period. Final data consisted of a total number of 1,902,071 milk test day records belonging to 226,255 first-parity cows (progeny of 5,094 sires and 178,390 dams) distributed in 797 herds and calved during 1996-2015 were utilized. For a mathematical description of the shape of the lactation curve, Wood’s incomplete gamma function was used. The function has three parameters including parameter a (associated with initial milk yield), parameter b (associated with the inclining slope of the lactation), and parameter c (associated with the declining slope of the lactation). Wood's function was fitted to the records of RM, FCM, and ECM of individual cows using SAS software. Based on the estimated parameters, lactation characteristics including peak time (PT), peak yield (PY), and persistency (Per) were subsequently calculated for each cow. Estimated parameters and calculated lactation characteristics were then subjected to a fixed linear model in which the effects of herd, year of calving, the season of calving, age at first calving, genotype group (grade or purebred Holstein), type of milk test day record (RM, FCM or ECM) along with some two-way interactions were included.  

The results showed that FCM had the greatest parameter a as compared with RM and ECM (P<0.0001). The greatest magnitude of the parameters b and c were found for RM (P<0.0001). Later PT and higher Per were observed for ECM (P<0.0001), while the highest PY was detected for RM (P<0.0001). For all types of records, minimum and maximum PY were observed for the cows calving in the spring and autumn seasons, respectively. Later PT was observed for ECM in all calving seasons except autumn. As compared to RM and FCM, cows calved in spring and summer had the highest persistency based on ECM while cows calved in autumn and winter were found to have more persistence based upon RM compared with FCM and ECM. The least-square means of peak time (PT) in grade cows were found to be 77.74, 69.5, and 79.85 d for RM, FCM, and ECM, respectively, while the corresponding figures for purebred Holstein cows were 80.27, 72.89, and 83.15 d, respectively. In grade cows, least-square means of peak time (PY) were found to be 32.02, 29.23, and 30.70 kg for RM, FCM, and ECM, respectively, while the corresponding figures for purebred Holstein cows were 32.51, 29.56, and 31.14 kg, respectively. For both purebred Holstein and grade cows, minimum and maximum persistency (Per) were obtained for FCM and ECM, respectively, which were significantly different from each other (P<0.001). For RM, FCM, and ECM, annual change trends of PT were found to be 2.132, 2.306, and 2.293 d, respectively, while the corresponding figures for PY were 0.408, 0.369, and 0.395 kg, respectively, and for Per were 0.037, 0.036, and 0.035, respectively. All trends were statistically significant (P<0.0001).

The finding of the present research revealed that purebred Holsteins reach the peak time later than grade cows which is an appropriate characteristic of the lactation curve. Based upon energy-corrected milk yield, peak time as well as persistency was found to be greater than those for raw milk and fat-corrected milk yields. Therefore, the use of energy-corrected milk yield could be suggested to be applied as different experimental nutritional treatments are to be compared in terms of the persistency of the cows. All lactation characteristics of Iranian dairy cows were found to be changed favorably over time.

The main aim of the present research was the genetic analysis of the first lactation milk yield trait and evaluation of the impact of selection for milk on the phenotype of age at first calving in Iranian dairy cows using quantile regression. Lactation milk records of 327190 first parity cows (progeny of 5260 sires and 235172 dams) in 637 herds (in 15 provinces) and calved between 2007 and 2015 were utilized. Genetic analysis was carried out with the use of an animal model. In the model, fixed effects of the province, herd, year and month of calving, covariates of lactation length, age at first calving, percentage of Holstein gene, as well as the random effect of the cow were included. The model was fitted on the data using the DMU package. Regression of age at first calving on predicted breeding value was fitted through a quantile regression model. The findings revealed that the heritability of lactation milk yield was equal to 0.276. Annual genetic gain in grade and Holstein purebred were found to be 17.352 (R2=0.913) and 23.398 (R2=0.962) Kg, respectively (P<0.0001). All estimated regression coefficients were negative in different percentiles of age at first calving and ranged between -0.0009 and -0.0344 (month per Kg) which indicates that the influence of genetic potential of cows for milk yield on different parts of calving age distribution is not the same.

The aim of this study was to investigate the effects of pomegranate seed pulp (PP) and its treated form with urea (PPTU) on performance, blood biochemical parameters and immune response of broiler chickens reared in heat stress condition. A total of 280 day-old Ross 308 chicks were used in a completely randomized design. The chicks were equally divided into seven treatments including 0, 3, 6 and 9 percent of PP and 3, 6 and 9 percent of PPTU with four replicates and 10 birds each. In heat stress period (25-42 days), the daily heat stress schedule was applied from 10:00 until 17:00 h for seven hours (35-37 oC). The PPTU increased the blood concentration of total protein (11 vs. 15.7 mg/dL). In heat-stressed chickens, PP increased body weight (1498 vs.1020 g) and decreased feed conversion ratio (1.82 vs. 2.56). The PP decreased the blood glucose concentration (611 vs. 1106 mg/dl) and also decreased the activity of the liver enzymes including alkaline phosphatase (1667 vs. 6483 U/L), aspartate aminotransferase (259.9 vs. 674.8 U/L) and lactate dehydrogenase (1506 vs. 3288 U/L). The immune response to SRBC in chickens fed PP with enzymes (9.25) or its urea-treated (8.5) were higher as compared to control (6.75). Therefore, these findings showed that the addition of pomegranate pulp with enzyme or its treated with urea up to 9% may improve performance, immune response and decreased the activity of liver enzymes in heat stressed broilers.

The central melanocortin system appears to be an important mediator of the actions of both leptin and insulin, which are key elements in the control of energy balance. Proopiomelanocortin (POMC) is a complex precursor protein that is proteolytically cleaved to a variety of biologically active and important neuroendocrine peptides. The POMC gene is expressed mainly in the anterior and intermediate lobes of the pituitary and in the arcuate nucleus of the hypothalamus, and at a lower level also in a wide variety of peripheral tissues and of brain regions in mammals. It produces many biologically active peptides via a series of enzymatic steps in tissue-specific manners, which have important roles in the regulation of appetite, sexual behavior, the movement of melanin produced from melanocytes in skin and the production of endogenous opioid peptides with widespread actions in the brain. In chicken, the POMC gene consisted of three exons and two introns and its protein has 251 amino acid residues with nine proteolytic cleavage sites, suggesting that it could be processed to give rise to all members of the melanocortin family, including adrenocorticotropic hormone and alpha-, beta- and gamma-melanocyte-stimulating hormones, as well as the other POMC-derived peptides.
Considerable evidence has been collected indicating that POMC mutations are associated with obesity.

Blood samples were collected in EDTA vials from one hundred Ross and sixty Cobb broiler chicks, stored at -20 and their DNA was extracted using the modified salting-out chloroform method. Polymerase chain reaction (PCR) was carried out by specific primer pairs to amplify a 444bp fragment from a part of exon two of the Pro-Opiomelanocortin gene. The pattern of all samples was determined through single stranded conformation polymorphism (SSCP) analyses by Acrylamide gel using silver nitrate staining.
The associations between polymorphisms (patterns) and the growth traits (live and carcass weight, and the weight of breast, thigh, back and neck, wings, liver, heart, bursa of Fabricius, pancreas, paraventricular, gizzard and spleen) were evaluated using the GLM procedure of the SAS software.

The extraction or genomic DNA and amplification of 444bp fragment of Pro-Opiomelanocortin gene were successfully done and it was polymorph in both strains. Two different patterns were found in Ross strain, E and F patterns with the frequencies of 0.56 and 0.44, respectively. Four different patterns were found in Cobb strain, A, B, C and D patterns with the frequencies of 0.63, 0.09, 0.14 and 0.14, respectively. There was no significant association between the patterns and the growth traits. In Ross strain, the effect of genotype (pattern) tend o be significant for carcass weight (p value = 0.054) and the chickens with F pattern have more carcass weight than those with pattern E. In Cobb strain, chickens with B pattern tend to have better slaughter yields compared to other patterns. Our results revealed that Cobb strain has more diversity in the studied fragment of POMC gene than Ross strain.

Energy homeostasis and body weight (BW) are regulated by coordinated actions of multiple genes. For significant economically traits, improvements in BW can be achieved through mass selection whereas feed conversion is relatively more difficult to improve. Gene polymorphisms can be used for improvement of the production traits by genetic selection, if the allelic association with the traits be determined. The variable associations of the identified polymorphisms may be a result of the differences in the population characteristics,
sex, or both, indicating that the selection criteria may influence the production trait associations. This should be taken into consideration while selecting for the desired production traits. Additional studies are required to expand the genetic and physiological aspects involved in feed intake, digestion, and metabolism. The genomic diversity also has important implications in the evolutionary dynamics of species. Investigations of polymorphisms are useful for better understanding of the gene function, and those associated with commercially significant production traits have a potential for usage as molecular markers for selection programs. In summary, the identified polymorphisms and their associations with the traits of economic importance in the present study provides greater insight into the role POMC gene involved in energy balance in poultry and points toward the
potential application of the findings for the enhancement of production traits by marker assisted selection.

Stress increases the need for antioxidants, decreases eggs production and weakens immune system of laying hens. Since there is insufficient knowledge about overcoming natural stress conditions with minimal cost and side effects in old laying hens, the medicinal herb contained flavonoid and polyphenolic compounds are concerned. Apart from estrogenic, antibacterial effects and cholesterol reduction property that will result to lower cholesterol deposition in poultry products and where calyx and leaf of Hibiscus sabdariffa
are known as potent antioxidant. Therefore, these experiments were designed to investigate the effect of Hibiscus sabdariffa extract as natural antioxidants on the immune system, blood biochemical parameters, plasma antioxidant status and the antioxidant balance of laying hens during molting and post-molting periods, also, laying performance and egg yolk cholesterol in the second phase of laying hen egg production.

In these experiments, aqueous-alcoholic extract of calyx and leaf of Hibiscus sabdariffa were prepared and sprayed on feed at levels of 300 and 700 mg/kg. One liter of %96
ethanol/distilled water mixture (30:70) were used to infuse 100 g each of the plant material (calyx or leaf) for 24 h. During the pre-experimental stage, minerals composition and antioxidant properties of Hibiscus sabdariffa were measured. Each of the main experiments, were conducted with 200 laying hens in a completely randomized design. In both experiments, five treatments consisted of control diet (basal diet), basal diet with 300 and 700 mg/kg of leaf extract of Hibiscus sabdariffa and basal diet with 300 and 700 mg/kg Hibiscus sabdariffa calyx extract. In both experiments, the blood cholesterol, total protein, triglyceride, LDL, HDL, glucose and malondialdehyde were evaluated by Spectrophotometer auto analyzer. In the end of each experiment, immune system and plasma antioxidant status for 2 samples from each replicate were determined. The egg production, egg weight, egg mass, feed intake and feed conversion ratio were recorded weekly. The egg malondialdehyde was determined during post molting period. In order to measure the level of yolk cholesterol and triglyceride, in the end of the experimental period, 2 samples were randomly taken from each replicate and after separating the yolks and mixing them, were analyzed by Spectrophotometer auto-analyzer with enzymatic method. The data were statistically analyzed with the general linear model by SAS software. The
mean differences between treatments were studied by Tukey's test.

Although there was more vitamin C in the leaf compared to calyx, the antioxidant activity including total antioxidants, phenols and anthocyanins in calyx were higher than
leaf. In both experiments, plasma antioxidant status of laying hens in a dose-independent manner were improved. During post molt period, attempt to increase oxidative stability of plasma and egg yolk also, improving plasma antioxidant status by dietary supplementation of Hibiscus sabdariffa extract was not significant, however, the Hibiscus sabdariffa calyx at 300 and 700 mg/kg levels, significantly affected plasma MDA and total antioxidant capability during molting period. In both experiments, the relative increase in antibody titers and the ratio of heterophil to lymphocyte were observed by all treatments as compared to the Control treatments. Hibiscus sabdariffa showed to have no significant effect on performance parameters. Probably, the negative effect of polyphenol compounds found in Hibiscus sabdariffa on digestive enzymes decreased lipid, protein and carbohydrates digestibility, thus reduced feed intake, egg weight and total blood protein, insignificantly, blood glucose and cholesterol, significantly. Also, the Hibiscus sabdariffa, especially leaf, decreased the yolk cholesterol and triglyceride. On the other hand, supplementation of Hibiscus sabdariffa at 700 mg/kg, improved production performance following feed conversion ratio compared with Control treatment that's probably due to quercetin and daidzein phytoestrogens found in Hibiscus sabdariffa. It seems that some compounds in Hibiscus sabdariffa, including phytoestrogens and organic acids that has been reduced the negative effect of other Hibiscus sabdariffa components on the performance of laying hens.

It can be concluded that Hibiscus sabdariffa, especially its leaves, which are discarded in most countries, including Iran, have the significant beneficial effects, such as anti-lipid effects, improvement of total plasma antioxidant and oxidative balance of old laying hens, with minimal cost and no significant negative effect on functional and immune parameters. It seems that finding of effective dose of Hibiscus sabdariffa is important to achieve layer hens’ maximum efficacy according to the test conditions and can economically be extended the range of its usage.

In feeding of dairy cows, well balanced diet and the proper amount of dietary fiber and particle sizeare necessary. Also, management of feed and feed intake is very important. On the other hand, increasing the intake of dry matter in lactating cows during early lactation is vital for improving milk production, animal health, and physical condition (Grant and Albright, 1995). One of the factors affecting animal health, is the physical properties of the feed, which has a strong relationship with the health of the digestive tract and animal feeding behaviors. Many researches have shown that cows tend to consume fine-grained components of their diet and makes selective consumption against larger components of the diet, while coarse components of the diet and long pieces are essential for animal health, because it increases rumination and chewing activity in animals (Stone, 2004). This experiment was carried out to evaluate effect of feeding frequency on feeding behavior, milk yield, and composition in dairy cows.

Twenty Brown Swiss dairy cows (average milk yield of 26.56 ± 5.2 Kg/d and 44.95 days in milk) were used in a completely random design for two periods. Two experimental treatments were applied. The experimental treatments were: 1- delivery of feed twice per day at 08:00 am and 8:00 pm and 2- delivery of feed three times per day at 08:00, 16:00 and 24:00. Each experimental period consisted of 21 days adaptability and 4 days recording of feeding behavior, milk yield, and composition. For all cows, eating activity and ruminating were recorded by visual method within 48 hours (first and second days during four-day sampling) at intervals of five minutes. Total chewing activity was calculated from the total time spent eating and ruminating. Sleep duration was measured at intervals of 10 minutes. Distribution of particle size was determined through PSPS (Penn State Particle Seprator). Approximate analysis of samples was undertaken by AOAC (2005). Neutral detergent fiber and acid detergent fiber were determined by the method of Van Soest (1991). Milk production was recorded on the third and fourth days of two sampling periods. Samples were taken at these days used to determine fat, protein, lactose, fat-free solids and urea by the means of milko scan system. Measurement of milk casein nitrogen, non-casein nitrogen, non-protein nitrogen of milk and true protein of milk were calculated by Raveland method (1938).

The results of this experiment showed that increasing the feeding frequency from two to three times a day increased the duration of eating, ruminating, chewing activity. Eating activity (minute / day) was significantly affected by experimental treatments (P<0.05). Delivery of feed three times a day increased the amount of time consumed for feeding. The increase in feed intake significantly increased the activity of chewing (734 vs. 771 minutes per day) (P<0.05). The most important feed-related factor affecting the activity of chewing is the physical structure and the chemical nature of the feed (Frooghi, 2005). With increasing feeding frequency, the activity of ruminant in standing position was reduced by approximately 10 minutes (P<0.05). This means that fewer frequency of feeding increased the level of ruminant activity in the standing position (Phillips and Rind, 2001). Also, the ruminant activity in the resting position was affected by experimental treatments and increased with increasing in feed delivery per day (P <0.0001). The results of this experiment showed that with increasing feed intake from two to three times a day, the selective consumption of feed components decreased and the consumption of NDF and long particles also increased (P<0.05). Therefore, increasing feeding has a more favorable effect on animal performance and prevents the separation of feed components (Jeziersky and Podluzny, 1984). The feeding frequency had a significant effect on the percentage of selection on screen 1.18 mm (short pieces) (P<0.05). This means that with increasing feed frequency, consumption from this screen was decreased. However, increasing feed intake, milk production was non significantly increased by 900 g/day. Also, increasing in the frequency of feed provision increased percent of protein, casein N and true protein of milk. However, increasing in the frequency of feed provision significantly decreased percent of milk urea (P<0.05). Perhaps the reason for the increase in milk protein with increasing feeding frequency is attributed to an increase in eating time and an increase in energy consumption in the form of concentrate or forage (Phillips and Rind, 2001). Feeding frequency had no significant effect on the percentage of milk solids- non- fat.

The results of this study showed that increasing feeding frequency can improve rumination and chewing activity and decrease the selective consumption of feed components. As the results of previous experiments showed, low feed intake increases competition between cows and also causes cows to wait for access to the feeder. So, excessive standing time can increase the risk of acidosis and laminits and reduce animal economic useful life.