Peak Milk Production Research Articles

Influence of supplemental choline on milk yield, fatty acid profile, and weight changes in postpartum ewes and their offspring.

The most intensive nutritional requirements occur during milk production's peak. Ewe milk contains more protein and fat than cow milk. The nutritional factors significantly determine the composition. The liver undergoes high stress during lactation but is relieved by essential nutrients. Choline acts metabolically as a lipotrope. This compound functions in cell structure construction, maintenance, and acetylcholine synthesis. The animal nutrition industry provides choline from various sources, such as synthetic and natural kinds. This study evaluated the influence of two distinct choline sources on dairy ewes' peripartum and postpartum milk production, composition, and offspring growth. Twenty-four Rambouillet ewes, each weighing around 63.7 ± 1.7 kg, aged three with two previous births, spent 30-day pre-partum and post-partum in individual pens (2 × 2 m). They were given different experimental treatments 30 days before and after birth according to a randomized design; no choline (a), 4 g/day rumen-protected choline (RPC) (b), or 4 g/day thiocholine (c). Milk samples for milk composition and long-chain fatty acid (FA) analysis were taken every 30 days during milk collection. Significant differences (p < 0.05) in ewe body weight, lamb birth weight, and 30-day-old lamb body weight were observed at lambing and on day 30 of lactation due to choline treatment. Milk yield was significantly higher (1.57 kg/day) compared to the control (1.02 kg/day) and RPC (1.39 kg/day), due to the herbal choline source. There was no significant difference in the milk's protein, lactose, fat, non-fat solids, and total milk solids content between the treatments. Herbal choline lowers (p < 0.05) the concentrations of caproic, caprylic, capric, lauric, and myristic acids while boosting (p < 0.05) those of oleic and cis-11-eicosenoic acid, the changes influencing long-chain FA levels (p < 0.05). Providing choline from both sources to ewes enhanced milk production and body weight at lambing and on 30-day post-lambing. The herbal choline supplement altered short-chain milk FAs, while representative concentration pathways affected medium-chain ones.

Longitudinal modeling of residual carbon dioxide and residual feed intake in the Nordic Red dairy cattle

Feed utilization efficiency is an important trait in dairy production playing a significant role in reducing feed costs and lowering methane emission. One of the metrics used to measure feed efficiency in dairy cows is residual feed intake (RFI). This metric requires routine measurement of feed intake. Since there is a positive high correlation between heat production and carbon dioxide (CO2) production on the one hand and heat production and efficiency on the other hand, residual carbon dioxide (RCO2) might be a useful metric to improve feed efficiency. The objectives of this study were to model the trajectories of RCO2 and RFI as well as to estimate their repeatabilities and correlations at different stages of lactation. Daily CO2 output and feed intake were recorded from 46 primiparous Nordic Red dairy cows using two Greenfeed Emissions Monitoring™ systems from 2 to 305 days in milk (DIM). Edited data comprised 5 995 daily averages. To calculate predicted values of CO2 and DM intake (DMI), prediction models were developed by fitting multiple regression models to observations. Subsequently, RCO2 and RFI were calculated by subtracting predicted values of CO2 and DMI from their corresponding actual observations. A random regression bivariate model was fitted to estimate repeatabilities and animal correlations within lactation at different DIMs between RCO2 and RFI traits. The model fitted included fixed effects of year-month of recording, lactation month, fixed regressions as well as random regressions for the animal effect. The residual variance was considered to be heterogeneous. Repeatabilities and animal correlations of RCO2 and RFI between selected DIM (for every 30 DIM i.e., 6, 36,…, 246 and 276) were calculated. Repeatability of RCO2 was high at the beginning of lactation (0.72 at DIM 6) and decreased around the peak of milk production (0.27 at DIM 96) and again increased gradually toward the end of lactation. Similarly, RFI also had high repeatability at the beginning (0.86 at DIM 6); however, it decreased in mid-lactation (0.37 at DIM 156) and then increased toward the end of lactation. Animal correlations between RCO2 and RFI were moderate to high on the same DIM and ranged from 0.37 to 0.88. Overall, we found that animals with higher CO2 production than expected also consume more DMI than expected, but the moderate correlation between RCO2 and RFI found in this study calls for more research to assess the potential of RCO2 to become a new feed efficiency metric.

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.

Lactation traits and reproductive performances of Sahraoui female camel in two breeding systems at Algerian Sahara.

The main objective of this study is to determine the impact of the camel livestock system on individual and herd performances of milk production, lactation curve, fats, and protein concentrations. For this purpose, 13 she-camels of Sahraoui breed from the south eastern Algeria and belonging and semi-intensive system (N = 6) and intensive system (N = 7) were studied. Recording and sampling of milk were carried out at regular intervals during a full lactation. The lactation curve was estimated using Wood's gamma function and the t-test of independent groups was carried out to compare lactation performances, lactation curve, and reproductive parameters. The overall average daily milk (DMY), fat (DFY), and protein (DPY) yield were 6.77 ± 0.82kg/day, 4.15 ± 0.91%, and 4.49 ± 0.20%, respectively. The mean of total milk yield (TMY) was 2696.39 ± 343.86kg during a mean lactation length (LL) of 398.38 ± 20.65days. The peak of milk production (6.79 ± 0.68kg) was reached at 93.9 ± 55.8days after calving. The open day (DO) and inter-calving interval (ICI) recorded in this study were 348.38 ± 30.33 and 723.38 ± 30.33days, respectively. There is no significant difference (p > 0.05) between intensive and semi-intensive breeding systems for TMY (2795.39 ± 261.88kg vs. 2580.89 ± 414.43kg), DMY (6.96 ± 0.66kg vs. 6.55 ± 1.00kg), and LL (402.14 ± 21.18days vs. 394 ± 21.03days). However, the total amount of fat was significantly higher in intensive system (182.02 ± 33.91kg) and the DPY content was significantly higher in semi-intensive system (4.60 ± 0.13%). The parameters α, β, and γ of lactation, fat, and protein curves between the two systems showed a highly significant difference (p < 0.01) for the parameters (α and β) for the milk production curve, significant (p < 0.05) for the time to reach peak yield, and no significance for the other parameters. The corresponding values of the coefficient of determination (R2) were 0.62, 0.35 for milk yield (p > 0.05), 0.12, 0.13 (p > 0.05) for fat, and 0.03, 0.11 (p < 0.05) for protein, in the intensive and semi-intensive systems, respectively. In addition, DO and ICI were not significantly different between the livestock systems, but were higher in the intensive system than the semi-intensive system (337.17 ± 26.26 vs. 712.17 ± 26.26, respectively). The study concluded that the intensive system had a higher milk performance with a more efficient lactation curve. The incomplete gamma model (Wood) used in this study was inappropriate for estimating milk yield, but acceptable for fat and protein.

Age at first calving and productive performance of primiparous Holsteins.

This study investigated the age at first calving in Holstein heifers and its impact on various production parameters. A sample of 737 Holstein heifers born between 2015 and 2018 and finishing their first lactations between 2018 and 2020 was included. Cluster analysis revealed three groups based on age at first calving: high precocity, medium precocity and low precocity. Medium-precocity group exhibited the highest 305-day milk yield and peak milk production. Additionally, the same group demonstrated superior mean production per lactation, 305-day milk protein content, and 305-day milk yield. The lowest somatic cell count was found in the low-precocity group. In conclusion, medium-precocity cows showed better results such as higher 305-day milk yield and peak milk production.

Survival Analysis On The Reproductive And Production Performances Of Dairy Cow In Bogor

The aim of this study was to analyze the reproductive performance (empty period) and production (peak time of milk production) of 87 dairy cows (Friesian Holstein) at X dairy farm Bogor using survival analysis. The analysis results based on the Kaplan-Meier curve showed that the median total idle time, primiparous cow, multiparous cow, cow that gave birth in the rainy and dry seasons were 210; 335; 231; 272; and 397 days. The median value of the total peak milk production, primiparous cow, multiparous cow, cow that give birth in the rainy and dry seasons is 41; 41; 39; 41; 41 days. The Cox Proportional Hazard regression results on idle time showed that the multiparous cow was 1.84 times more likely (P&lt;0.05) to have a shorter idle period than the primiparous cow. Cows that gave birth during the rainy season had a 1.80 times shorter chance than cows that gave birth during the dry season, although they were not statistically significantly different (P=0.043). The regression results on peak milk production showed no difference between cows and primiparous cows. Meanwhile, cows that gave birth during the rainy season experienced peak lactation 1.26 times and tended to be faster than cows that gave birth during the dry season, although this was not statistically significant. The study's conclusions show that it was necessary to improve the management of reproduction and production of X dairy farm in Bogor.

Dairy Cows Transition Period Feeding and Management

Proper feeding during the pregnancy and post-pregnancy period, determines the milk Production, ensuing lactation and as well as, the reproductive efficiency of the animal. 3 weeks before and 3 weeks after parturition are very important because a dramatic physiological and metabolic adaptation occurs during this period which is called the transition period. The Nutritional imbalances are caused by the low quality of desired nutritious rations, reduced appetite, and low ingestion which are responsible for depressed performance, specifically during the transition period. The absence of knowledge and skills of farmers in feeding management during the transition period exacerbates the situation. The metabolic changes, metabolic adaptations, Mechanism of a Transition period, transition period feeding management to prevent disorder, Decreased dry matter intake (DMI), Nutrient requirements, Infectious diseases and metabolic disorders, Nutritional management to Ease out the Transition Period, Management of the transition period, Feed additives supplementation and nutritional-management strategies to passage transition period are discussed by this review paper. Simultaneously, with the growth of the fetus, the nutrient requirements increase and are at their peak before parturition as well as immediately after parturition. The peak milk production reaches about 5–8 weeks postpartum, while the diet consumption peaks at 10–14 weeks postpartum. So, dairy cows will typically suffer a 6–8-week period of negative energy balance during the postpartum period. The requirement energy of the mammary at 4 days postpartum is more than three times than that of the uterus, with a simultaneous increase in the requirement of metabolizable protein, especially of methionine and lysine. The high metabolic incidence of infectious diseases is responsible for the high incidence of inflammatory conditions, mostly immediately after calving. To prevent mentioned diseases, pro-inflammatory cytokine release should be avoided postpartum. The body reserves mobilization, especially fat and protein; and hepatic gluconeogenesis takes place immediately after parturition leading to increased levels of β-hydroxy butyric acid and non-esterified fatty acids, which act as a gateway for several metabolic diseases. The phase of transition may eased by increasing DMI, feed conversion efficiency, density of ration, and protein supplements rich in rumen un-degradable protein; by using anionic mineral mixture, optimizing roughage to concentrate (R: C) ratio, optimum physically effective fiber length of forages/silage/hay, dietary buffers, feed additives such as inflammation modulators, protected nutrients, glucogenic precursors and direct-fed microbial/probiotics.

The effect of insulin-like growth factor 1 receptor gene single nucleotide polymorphism on growth and milk production traits in two native Indian tropical goat breeds

Insulin like growth factor1(IGF-1) is an essential growth factor that mediates the growth-promoting functions of pituitary growth hormone. Insulin like growth factor 1 receptor (IGF1R) is a tyrosine kinase receptor that mediates the actions of IGF1. Therefore, IGF1R is a candidate gene for examining SNPs linked with growth and production traits. The objective of this study was to detect the c.546 + 179170A > T transversion in intron 2 of the gene encoding IGF1R in two goat breeds, Attappady Black and Malabari, and examine the association of this polymorphism with growth and milk production. For the identification of the SNP, the T-ARMS-PCR was utilized. All three genotypes were present in the two investigated breeds. The polymorphism was found to be significantly (p < 0.05) linked with growth traits. At birth, 3 and 6 months of age, Attappady goats with the AT genotype had significantly (p < 0.05) higher body weights than those with the AA and TT genotypes. Malabari goats with the AT genotype had significantly (p < 0.05) higher body weights at birth and at 3 months of age. The genotypes of the IGF1R gene had no effect on total or peak milk production. Therefore, this SNP could be used as a molecular marker in selection of meat-producing goat breeds. HIGHLIGHTS c.546 + 179170A > T IGF1R transversion was detected using T-ARMS-PCR in two indigenous goat breeds from Kerala. Attappady Black and Malabari goat breeds of Kerala possessed all the three genotypes In these breeds, there was a significant correlation between this SNP, c.546 + 179170A > T IGF1R, and body weight. In both the breeds, there was no association between this SNP and milk production traits.

Milk Production and Reproductive Performance of Holstein Friesian Dairy Cattle in the Working Area of ​​South Bandung Pangalengan Animal Husbandry Cooperative (KPBS) Bandung Regency

Increasing the population and productivity of dairy cows is one of the way to boost national milk production capacity. This study was aimed to determine and investigate the performance of milk production and reproduction of Friesian Holstein (FH) dairy cows in the Working Area of KPBS Pangalengan, Bandung Regency. This research used FH dairy cows with a complete milk production and reproduction record. In total, there were 90 heads of cows in the Pangalengan District and 178 heads of cows in the Kertasari District. This study used the survey method to collect the data. A Multistage Random Sampling Method was used in this research. Sampling was carried out in two stages, the first stage was sampling from two sub-district locations in Pangalengan and Kertasari Districts. In the second stage, two villages were selected from each district: Pangalengan and Margamukti Villages in Pangalengan District, and Santosa and Tarumajaya Villages in Kertasari District. Farmers and their cows were chosen by simple random sampling. Data on milk production and reproduction records were obtained from farmers and their cows through direct observation and interviews related to the identity of the cattle they owned. The results showed that the average performance of the milk production characteristics of FH dairy cows was: an average milk production of 3779.2±497.48 liters/head/day, an average length of lactation of 307.8±31.30 days, and an average dry period of 72.14±21.43 days. The lactation period had a significant effect (P&amp;lt;0.05) on milk production. The peak of milk production was reached in the fourth lactation period. The mean of reproductive traits consisting of the first postpartum mating was 77±20.5 days, the average length of days open was 96±26.4 days, the average number of services per conception was 1.8±0.85 times, and the average calving interval was 381.05± 24.5 days. In conclusion, FH dairy cows raised in Pangalengan and Margamukti Villages, Pangalengan District, Santosa and Tarumajaya Village, Kertasari District, in the working area of Pangalengan KPBS during the Covid-19 pandemic indicated a fairly good performance of milk production and reproduction characteristics.

Fur removal promotes an earlier expression of involution-related genes in mammary gland of lactating mice

Peak lactation occurs when milk production is at its highest. The factors limiting peak lactation performance have been subject of intense debate. Milk production at peak lactation appears limited by the capacity of lactating females to dissipate body heat generated as a by-product of processing food and producing milk. As a result, manipulations that enhance capacity to dissipate body heat (such as fur removal) increase peak milk production. We investigated the potential correlates of shaving-induced increases in peak milk production in laboratory mice. By transcriptomic profiling of the mammary gland, we searched for the mechanisms underlying experimentally increased milk production and its consequences for mother–young conflict over weaning, manifested by advanced or delayed involution of mammary gland. We demonstrated that shaving-induced increases in milk production were paradoxically linked to reduced expression of some milk synthesis-related genes. Moreover, the mammary glands of shaved mice had a gene expression profile indicative of earlier involution relative to unshaved mice. Once provided with enhanced capacity to dissipate body heat, shaved mice were likely to rear their young to independence faster than unshaved mothers.

Milk yield, milk composition and reproductive performance of Baggara cattle as affected by parity under traditional system, Sudan

This study was conducted to evaluate parity order on milk yield and milk components and calving interval of Baggara cattle as affected by parity in West Kordofan State, Sudan. Forty eight cows were selected from the herd of Baggara cattle. The cows were weighed and divided into four groups A, B, C and D, each group comprised of (12) cows according to parity order, first, second, third and fourth parity. Data were analyzed by using F test for analysis of variance procedures and Duncan’s multiple range test (DMRT) for mean separation. All cows were raised on natural grazing. The results revealed that parity order significantly (p&lt;0.05) affected daily, monthly and total milk yield. Milk production increased with advance parity. High (p&lt;0.05) milk yield, monthly and daily milk scored by 3rd parities as 668.47 kg, 133.73kg and 4.49kg respectively. Results showed significant differences (p&lt;0.05) between different parities for the milk composition during first and third month of lactation period, with high fat percentages in first month for 2nd parities (6.21) and 3rd parities (6.26) in 3rd month of lactation. The results indicated that calving days to first estrus and days to conceive were significantly (P&lt;0.05) effected by parity number. Shorter days to show estrus was obtained by primiparous cows (56.19 ±8.72 days), also Days to conceive exerted significant (P&lt;0.05) effect parity order. Results showed a significant differences (p&lt;0.05) between different parities order for calving interval, that short days of calving interval scored by primiparous parities (10.04 months) and long days by 4th parities (13.17month). In conclusion, Baggara cows that depended on natural grazing reached its peak milk production in third parity with considered that the main purpose of these animals for meat production.

Quantifying the negative impact of clinical diseases on productive and reproductive performance of dairy cows in central Argentina

In dairy herds, cattle experience different health disorders, and their occurrence during lactation may cause important economic losses. The systematic analysis of productive and health records allows us to identify the risk factors of greatest negative incidence on profitability in commercial dairy farms. The aim of this work was to estimate the effects of clinical diseases on the productive and reproductive performance of dairy cattle. A total of 15,423 lactations (≥3rd lactations) were analyzed; data involved records of three years obtained from 21 commercial dairy farms randomly selected from the main milk-producing provinces in Argentina. Lactations were classified as “with” (WD) or “without” (WOD) clinical diseases. The parameters production at peak (Ppeak) and 305-d cumulative milk production (305DY) were estimated and lactation curves were fitted using the MilkBot model. Statistical differences were found between lactations with at least one clinical disease (305DY 9,861.3 kg; Ppeak 39.5 kg/d) and those WOD (305DY 10,013.6 kg; Ppeak 40.2 kg/d). The reproductive indicators days open and days to culling were derived from survival analysis. Days open showed that 50% of cows with at least one clinical disease became pregnant 181 days (95% CI = 177; 185) after parturition, whereas in cows without clinical disease, pregnancy occurred on average 126 days (95% CI= 121; 132) after parturition. Furthermore, for days to culling, 50% of the diseased cows exhibited a culling time of 518 days (95%CI = 508; 527), whereas healthy cows remained in the herd for a longer period, on average 563 days (95% CI= 541; 586). The results suggest significant residual effects, i.e. the consequences of clinical disease are not limited to the period of disease progress, but extend to periods after the clinical resolution of the disease.

Effects of short and long milking intervals on milking characteristics and changes of milk constituents during the course of milking in crossbred Istrian × Awassi × East-Friesian ewes.

The main objective of this experiment was to evaluate the effects of two milking intervals (8 and 16 h) on milk constituents (fat, protein, lactose, dry matter, and log10 SCC) of nineteen Istrian × Awassi × East-Friesian crossbred ewes in different milk fractions (0-25, 25-50, 50-75 and 75-100%) during the course of milking and in machine stripping (MS) milk. Furthermore, we sought to determine the effect of the two milking intervals on milking characteristics (average milk flow rate, peak milk flow rate, machine-on time, total milk yield, and milk production rate) and whether each milk constituent within each milking interval is best described by a linear, quadratic, or cubic function. Average milk flow rate and milk yield per milking decreased in the 8 h milking interval compared to the 16 h milking interval (P < 0.05). Peak milk flow rate, machine-on time, and milk production rate were not different between the two milking intervals. Overall, milk fat content, dry matter content, and log10 SCC increased in the 8 h milking interval compared to the 16 h milking interval (P < 0.05). Milk protein content did not change through the main milk fractions at either milking interval. Milk lactose content did not change through the milk fractions at the 8 h milking interval, whereas it decreased in the 75-100% and stripping milk fractions at the 16 h milking interval (P < 0.05). The 0-25% and stripping milk fractions contained the highest log10 SCC compared to all other milk fractions (P < 0.05). Changes of milk fat and dry matter content throughout milking were best described by quadratic functions, whereas milk protein content, milk lactose content, and log10 SCC were best described by different functions depending on the milking interval. These results demonstrate that milking interval influenced all milk constituents in various milk fractions during the course of ewe milking. Moreover, milking characteristics such as average milk flow and total milk yield, and the appropriate mathematical function to characterize milk constituents throughout a milking, were affected by milking interval.

Effects of replacement of corn silage and distillers' grain diets with hay during prepartum on the health and production performance of dairy heifers postpartum.

In this study, we aimed to comprehensively evaluate the effects of prepartum replacement of corn silage and distillers' grain diets with hay on the postpartum health and production performance in dairy heifers. Pregnant Holstein dairy heifers were randomly assigned to two groups and fed different diets with the same net energy and protein concentrations. The low corn silage plus hay (CH) group diet mainly contained oat hay (28.5%), corn silage (25%) and folium ginkgo (23%). The high corn silage plus distillers' grains (CD) group diet contained corn silage (53.5%), distillers' grains (5%) and folium ginkgo (18%). Dairy heifers were fed from the beginning of pregnancy to the end of the transition period. Calf birthweight, postpartum morbidity, milk production and reproductive performance were determined. Compared with the cows in the CH group, those in the CD group presented increased calf birthweight and a high risk of some postpartum disorders (p<0.05), particularly ketosis (37.63% vs. 24.54%) and retained placenta (9.41% vs. 3.92%). However, there was no difference between the groups in reproductive performance, including first timed artificial insemination (TAI) rate, date of TAI and conception rate of TAI. The lactation curves showed no difference in milk yield during the peak lactation period of primiparous cows between the CH and CD groups; the total milk production was 33.39kg and 33.19kg respectively. Notably, the time to peak milk production was delayed in the CD group. It can be concluded that replacing corn silage and distillers' grains with hay can reduce postpartum morbidity in dairy heifers and shorten the time to peak milk production.

Detection of the effect of PIT-1 gene genotypes on some productive traits in Holstein cattle

The research was conducted at the Taj Al-Nahrain cattle station in Al-Diwaniyah governorate in Iraq on a sample of 85 Holstein cows imported from Germany, which were selected during the third season of milk production, in order to determine the genotypes of the PIT-1 gene and its relationship to a number of production traits. The PCR product (451bp) of the PIT-1 gene was digested using the Hinf1 restriction enzyme, and the digestion results showed that the studied genetic segment of the POU1F1 gene appeared in three genotypes (AA, AB, and BB) with percentages of 55.3, 42.6, 2.1%, respectively, and there were highly significant differences (P≤0.01) between the distribution of these percentages, and the A allele (0.766) was superior to the B allele (0.234). The results of the analysis of variance showed that the effect of the genotype of the POU1F1 gene on the characteristics of milk production (daily milk production, total milk production, peak production) was not significant except in the characteristic of peak milk production in favor of the BB genotype at a rate of 538.50 kg on each of the genotypes AA and AB while the results did not show a significant effect between the genotypes (AA, AB, BB) in both the daily milk production rate and the total milk production. It was found that the effect of the POU1F1 gene on body dimension traits (body length, frontal body height, posterior body height) was significant (P≤0.05) in body length in favor of the BB genotype (164 cm) on each of the genotypes AA and AB, at 157,780. and 156,347 cm, respectively, while there were no significant differences between the genotypes in the anterior height and posterior height of the body.

Detection of Subclinical Ketosis in Urine of Cattle and Buffaloes

Background: Subclinical ketosis (SCK) in dairy cows is a common metabolic disorder and a strong determinant of the health and performance of cows throughout lactation. Considerable amount of milk loss takes place with SCK incidence in dairy animals. Greater benefits are to be gained by monitoring the cows for SCK. The current study was aimed to find out incidence of SCK by urine test strip (Keto-Diastix). Methods: The present investigation was carried out on crossbred and Sahiwal cows and Murrah buffaloes (n=180) of the institute herd and rural dairy farms (n=97) around Karnal. The urine samples were tested for subclinical ketosis (SCK) 5-60 days postpartum from August 2019 to March 2020. Meteriological data on wet and dry bulb temperature and ambient temperature was collected and THI was calculated. Data of SCK incidence was classified based on stages of early lactation (5-20, 21-40 and 41-60d), parity (I, II, III and above), seasons (hot-humid, autumn, winter and spring) and milk production level ( less than 10kg, 10-20 kg and greater than 20 kg/d). Milk yield and environment variables were recorded during the experiment. Urine ketone and glucose level was detected by keto-Diastix to find out incidence of SCK. Result: Mean level of ketone bodies in urine was higher (P less than 0.01) in high yielding cows as compared to the medium yielders; however it did not vary in buffaloes. Ketone bodies in urine were high (P less than 0.01) in crossbred cows than that of buffaloes and Sahiwal cows. Urine glucose level did not vary among cows and buffaloes. It is concluded that high producing crossbred cows are more vulnerable to SCK between 41-60d of lactation and in III parity and above due to peak milk production. Sahiwal cows and buffaloes suffer less from SCK probably due to medium level of milk production. Factors like high milk yield, higher parity and hot-humid stress makes the animal more vulnerable to SCK. The screening of urine samples of animals at monthly intervals may be practiced by the farmers to monitor the incidence of SCK.

The impact of declining dairy fertility on calving patterns and farm systems: A case study from northern Victoria, Australia

CONTEXTFertility is crucial for pasture-based seasonal calving dairy herds, where cows are expected to calve in a single cohort at a time when peak milk production coincides with maximum pasture availability. However, dairy fertility has declined globally, and many Australian herds now use a split calving system, where non-pregnant cows are given additional opportunities to conceive by having two mating periods per year. Other factors prompting a move to split calving may include financial incentives for producing out-of-season milk, increasing levels of concentrate feeding, and pressure due to extreme seasonal conditions – all of which are particularly apparent in the northern Victorian irrigation region. OBJECTIVEThe aim of our study was to describe the fertility and herd characteristics of the study population and to examine changes in reproductive performance and calving systems that have occurred over the same period. METHODSOur study population included 38 herds from the northern Victorian irrigation region in Australia. We collected individual cow records from each herd from the date on which they started herd recording (with a median start year of 2000 for mating event data) up until December 2016, comprising both fertility-related data such as insemination records, calving dates, and pregnancy test results, and systems-related data such as production, herd size and calving pattern. RESULTS AND CONCLUSIONSFrom a relatively small number of herds, we were able to obtain a dataset comprising 438,578 mating and pregnancy test records for 86,974 cows. From 2003 to 2016, 6-week in-calf rate and first service conception rate declined in the study population for both Holstein-Friesians and Jerseys, while 3-week submission rate remained unchanged. At the same time, the proportion of split calving herds in our cohort markedly increased, with a significant expansion in herd size compared to their seasonal counterparts. The proportion of first parity heifers in herds also increased, which may be a function of increasing herd size, or involuntary culling due to poor fertility. SIGNIFICANCESplit calving represents a significant system change for herd managers, with concomitant effects on labour management, input costs, and the lifestyle they experience. However, if this change has been implemented due to poor fertility without considering whether the increased income outweighs increased input costs, then a suboptimal decision may have been made. Finally, high quality data remains underutilised on individual farms, with significant benefits to the Australian dairy industry if we can overcome the numerous challenges to access it.

ЛАКТАЦИОННАЯ ДЕЯТЕЛЬНОСТЬ КОРОВ-ПЕРВОТЕЛОК В УСЛОВИЯХ РОБОТИЗИРОВАННОГО ДОЕНИЯ

Studies have been conducted to assess the lactation productivity of Kholmogory breed Tatarstan type first-calf cows with robotic milking systems. The frequency of milking distribution during the day was observed: in the interval of 4-6 hours, the minimum number of milking occurs (6.4 %), in the interval of 12-14 hours, the maximum number (10.7 %). Most milking (34.7 %) is carried out in 6-8 hours after the previous one. More frequent milking (after 4-6 hours) is rarely observed is in 6 % of cases. 48.6 % of milking occurs after the 8-12 hour interval. For an interval of more than 12 hours occurs for 10.7 % of milking. With an increase in the milking interval, the milk yield also increases. At 4-6 hour interval, the milk yield is 5.2 kg, at 6-8 hour is 6.0 kg. An increase in the milking interval by 2 hours is accompanied by an increase in the single milk yield by 0.8-1.3 kg. During the first month, the cows were milked the least number of times, which was 75, or 2.4 times per day; during the second month, they were milked 86 times (2.8 per day). By the 4th month, milkings reached a peak of 93 times (3 per day). By the 5th month, a decline was observed (by 11 % compared to the 4th month). The peak milk production takes place during the second month of lactation, 681.3 kg. By the third month, a decline was observed by 4.8 %, to 648.1 kg. The maximum decrease in milk production, by 12.4 %, occurred between the 5th and 6th month of the tested lactation period.

KORELASI PRODUKSI SUSU DENGAN BCS SAPI FRIESIAN HOLSTEIN LAKTASI PERTAMA DI BBPTU-HPT BATURRADEN

The purpose of this study was to determine the relationship between milk production of PFH dairy cows with BCS at the first lactation at BBPTU HPT Baturraden. The study was conducted from March 20 to April 20 2018, with research material consisting of 250 production data records and 250 BCS data records that were corrected in lactation months 1 to 10 originating from BBPTU HPT Baturraden. Data analysis shows that milk production has a close relationship with lactation month, the results are shown by the equation y = -0.1223x2 + 0.6068x + 13.493 with R2 of 0.97. These results are reflected in the milk production curve which shows in the first month to the third month that there is an increase in milk production, with peak production being reached in the third month. Average peak milk production is 14.74 liters / head / day and average milk production Daily 12.12 liters / head / day. The results of the BCS analysis show that BCS has a close relationship with the lactation month, the results are shown by the equation y = 2.9133 + 0.0132x2 + 0.0365x shown with R2 of 0.95. The results on the BCS graph show that BCS is increasing as the lactation period progresses, the largest average BCS is obtained 3.79 in the 10th month. The relationship between milk production and BCS based on the analysis shows the equation y = -3,9224x2 + 18,894x - 7,6087, indicated by an R2 of 0.98.

Comparison of three methodologies for the genetic study of lactation persistency in Holstein cattle from Antioquia.

Persistency is the rate of decrease after milk production peak, mathematical models such as Wood's can be used to estimate it for describing the lactation curve and its rate of descent; random regression models are also useful, as they describe the genetic lactation curve for each animal. The objective of this study was to compare Best Linear Unbiased Prediction (BLUP), marker-assisted BLUP (MBLUP) model and random regression model (RRM) to estimate genetic parameters and breeding values for the lactation persistency curve. 4,658 test day measurements were available for 733 individuals, from which lactation curves were described to calculate persistency, estimating genetic parameters and values for this trait through BLUP and MBLUP. A similar process was done for RRM, where persistency was estimated from the genetic lactation curve. The heritability obtained using RRM was 0.51, greater than that obtained by BLUP (0.29) and MBLUP (0.21). The reliability of the genetic value for persistency in bulls was greater when RRM was used, but there was no correlation between the genetic values of different models. The highest heritability for persistency and the more reliable genetic values for bulls were achieved under the RRM, it allows positioning this methodology as an important tool for genetic evaluation of persistency.