Milk Yield In Dairy Cattle Research Articles

A Meta-Analysis of the Effects of Dietary Betaine on Milk Production, Growth Performance, and Carcass Traits of Ruminants.

Betaine improves growth performance and health in monogastric animals under both thermoneutral and heat stress conditions, but results in ruminants have been more equivocal. This meta-analysis investigated the effects of betaine supplementation on productive performance, milk production and composition, and carcass traits of ruminants due to betaine supplementation. A comprehensive search for published studies investigating the effect of betaine was performed using Google Scholar, ScienceDirect, PubMed, and Scopus databases. Effect size analysis, random effects models, I2 statistics, and meta-regression analysis were utilized to assess differences in production parameters. Dietary betaine supplementation increased milk yield (+1.0 kg/d (weighted mean differences presented in this abstract), p < 0.001), dry matter intake (+0.15 kg/d, p < 0.001), and milk lactose (+0.05%, p = 0.010) in dairy cows housed under thermoneutral conditions. In the few studies conducted on small ruminants, there was an increase in milk yield in response to dietary betaine (0.45 kg/d, p = 0.040). Under heat stress conditions or grazing pasture during summer, dietary betaine increased milk yield (+1.0 kg/d, p < 0.001) and dry matter intake (+0.21 kg/d, p = 0.020). Dietary betaine increased final liveweight (+2.33 kg, p = 0.050) and back fat thickness (+0.74 cm, p < 0.001) in beef cattle. Dietary betaine increased final liveweight (0.14 kg, p = 0.010), daily gain (+0.019 kg/d, p < 0.001), and carcass weight (+0.80 kg, p < 0.001) but not backfat in small ruminants. These meta-analyses showed that dietary betaine increases liveweight in small ruminants and beef cattle and increases feed intake and milk yield in dairy cattle.

Mendelian randomization analysis of 34,497 German Holstein cows to infer causal associations between milk production and health traits

BackgroundClaw diseases and mastitis represent the most important health issues in dairy cattle with a frequently mentioned connection to milk production. Although many studies have aimed at investigating this connection in more detail by estimating genetic correlations, they do not provide information about causality. An alternative is to carry out Mendelian randomization (MR) studies using genetic variants to investigate the effect of an exposure on an outcome trait mediated by genetic variants. No study has yet investigated the causal association of milk yield (MY) with health traits in dairy cattle. Hence, we performed a MR analysis of MY and seven health traits using imputed whole-genome sequence data from 34,497 German Holstein cows. We applied a method that uses summary statistics and removes horizontal pleiotropic variants (having an effect on both traits), which improves the power and unbiasedness of MR studies. In addition, genetic correlations between MY and each health trait were estimated to compare them with the estimates of causal effects that we expected.ResultsAll genetic correlations between MY and each health trait were negative, ranging from − 0.303 (mastitis) to − 0.019 (digital dermatitis), which indicates a reduced health status as MY increases. The only non-significant correlation was between MY and digital dermatitis. In addition, each causal association was negative, ranging from − 0.131 (mastitis) to − 0.034 (laminitis), but the number of significant associations was reduced to five nominal and two experiment-wide significant results. The latter were between MY and mastitis and between MY and digital phlegmon. Horizontal pleiotropic variants were identified for mastitis, digital dermatitis and digital phlegmon. They were located within or nearby variants that were previously reported to have a horizontal pleiotropic effect, e.g., on milk production and somatic cell count.ConclusionsOur results confirm the known negative genetic connection between health traits and MY in dairy cattle. In addition, they provide new information about causality, which for example points to the negative energy balance mediating the connection between these traits. This knowledge helps to better understand whether the negative genetic correlation is based on pleiotropy, linkage between causal variants for both trait complexes, or indeed on a causal association.

Genetic aspects of immunoglobulins and cyclophilin A in milk as potential indicators of mastitis resistance in Holstein cows

Mastitis is one of the most frequent and costly diseases affecting dairy cattle. Natural antibodies (immunoglobulins) and cyclophilin A (CyPA), the most abundant member of the family of peptidyl prolyl cis/trans isomerases, in milk may serve as indicators of mastitis resistance in dairy cattle. However, genetic information for CyPA is not available, and knowledge on the genetic and nongenetic relationships between these immune-related traits and somatic cell score (SCS) and milk yield in dairy cattle is sparse. Therefore, we aimed to comprehensively evaluate whether immune-related traits consisting of 5 Ig classes (IgG, IgG1, IgG2, IgA, and IgM) and CyPA in the test-day milk of Holstein cows can be used as genetic indicators of mastitis resistance by evaluating the genetic and nongenetic relationships with SCS in milk. The nongenetic factors affecting immune-related traits and the effects of these traits on SCS were evaluated. Furthermore, the genetic parameters of immune-related traits according to health status and genetic relationships under different SCS environments were estimated. All immune-related traits were significantly associated with SCS and directly proportional. Additionally, evaluation using a classification tree revealed that IgA, IgG2, and IgG were associated with SCS levels. Genetic factor analyses indicated that heritability estimates were low for CyPA (0.08) but moderate for IgG (0.37), IgA (0.44), and IgM (0.44), with positive genetic correlations among Ig (0.25-0.96). We also evaluated the differences in milk yield and SCS of cows between the low and high groups according to their sires' estimated breeding value for immune-related traits. In the high group, IgA had a significantly lower SCS in milk at 7 to 30 d compared with that in the low group. Furthermore, the Ig in milk had high positive genetic correlations between healthy and infected conditions (0.82-0.99), suggesting that Ig in milk under healthy conditions could interact with those under infected conditions, owing to the genetic ability based on the level of Ig in milk. Thus, Ig in milk are potential indicators for the genetic selection of mastitis resistance. However, because only the relationship between immune-related traits and SCS was investigated in this study, further study on the relationship between clinical mastitis and Ig in milk is needed before Ig can be used as an indicator of mastitis resistance.

Identifying the Most Important Linear Body Depth Traits Associated with Milk Yield in Dairy Cattle

Depth dimensions are a fundamental linear type trait in the animal body included in dairy cattle science. Unfortunately, the prominent body depth dimension to milk yield is unspecified in lucidity. Thus, the objective of the current research was to identify the excellent body depth dimension of dairy cattle for milk yield as a selection precedence trait. The experiment employed 121 lactation Holstein cows aged specify as 2–6, raised on an Indonesian smallholder commercial dairy farm. R version 4.2.1 with RStudio software simultaneously worked as a statistical analysis tool. The principal component analysis (PCA), correlation, and regression analyses were executed sequentially. The product of the PCA revealed that the chest depth (CHD), body depth (BDD), and udder depth (UDD) traits are the essential body depth dimensions in dairy cattle. A crowning envoy associated with the milk yield capacity was delegated to the UDD trait. However, the UDD is the finest trait for the lactation cow selection program. Presumably, the BDD trait is the prime characteristic for calves and heifer selection schemes.

Meta-analysis of MspI derived variants of growth hormone gene associated with milk yield in dairy cattle

ObjectiveThe present work aimed to obtain common effect sizes for the gene frequency and association of MspI derived variants of growth hormone (GH) gene with milk yield in dairy cows. MethodsWe performed a systematic review and meta-analysis of 35 published studies identified in literature search from 2000 to 2020 (n = 4164). These studies were specific to fragment size (329) for genotypes viz., CC (224, 105 bp), CD (329, 224, 105 bp) and DD (329 bp). Pooled standard mean differences (SMDs) as effect sizes between allele pairs were derived using different genetic models. The heterogeneity between effects sizes across studies was estimated using I2 Index (%). ResultsThe common effect size for gene frequency of allele C (224, 105 bp) was significantly (P < 0.05) higher in 2881 Bos taurus/cross cows (0.82; 95% CI: 0.74, 0.89; I2 = 97.81%) than 1283 Bos indicus cows (0.15; 95% CI: 0.12, 0.18; I2 = 71.90%), with overall gene frequency was 0.33 (95% CI: 0.21, 0.46; I2 = 99.29%). Additive (CC vs. DD) and dominant (CC + CD vs. DD) did not revealed significant (P > 0.05) association with milk yield. However, completely over dominant (CC + DD vs. CD) and recessive (CC vs. CD + DD) models showed significant (P < 0.05) and positive SMDs with milk yield specially at early lactations. There was no evidence of heterogeneity (I2 = 0.00%) between SMDs across studies. ConclusionsThis meta-analysis suggested potential association of C allele for enhancing milk production of dairy cows.

Epidemiological study on Listeria monocytogenes in Egyptian dairy cattle farms’ insights into genetic diversity of multi-antibiotic-resistant strains by ERIC-PCR

Listeria monocytogenes (L. monocytogenes) is frequently detected in ruminants, especially dairy cattle, and associated with the sporadic and epidemic outbreak of listeriosis in farms. In this epidemiological study, the prevalence, virulence, antibiotic resistance profiles, and genetic diversity of L. monocytogenes in three Egyptian dairy cattle farms were investigated. The risk factors associated with the fecal shedding of L. monocytogenes were analyzed. The L. monocytogenes strains from the three farms were categorized into distinct genotypes based on sampling site and sample type through enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR). A total of 1896 samples were collected from animals, environments, and milking equipment in the three farms. Results revealed that 137 (7.23%) of these samples were L. monocytogenes positive. The prevalence of L. monocytogenes in the animal samples was high (32.1%), and the main environmental source of prevalent genotypes in the three farms was silage. For all sample types, L. monocytogenes was more prevalent in farm I than in farms II and III. Risk factor analysis showed seasonal variation in production hygiene. For all sample types, L. monocytogenes was significantly more prevalent in winter than in spring and summer. The level of L. monocytogenes fecal shedding was high likely because of increasing age, number of parities, and milk yield in dairy cattle. Two virulence genes, namely, hlyA & prfA, were also detected in 93 strains, whereas only one of these genes was found in 44 residual strains. Conversely, iap was completely absent in all strains. The strains exhibited phenotypic resistance to most of the tested antibiotics, but none of them was resistant to netilmicin or vancomycin. According to sample type, the strains from the animal samples were extremely resistant to amoxicillin (95.2%, 80/84) and cloxacillin (92.9%, 78/84). By comparison, the strains from the environmental samples were highly resistant to cefotaxime (86.95%, 20/23). Furthermore, 25 multi-antibiotic resistance (MAR) patterns were observed in L. monocytogenes strains. All strains had a MAR index of 0.22–0.78 and harbored antibiotic resistance genes, including extended-spectrum β-lactamase (blaCTX-M [92.7%] and blaDHA-1 [66.4%]), quinolones (qnrS [91.2%], qnrA [58.4%], parC [58.4%], and qnrB [51%]), macrolides (erm[B] [76.6%], erm(C) [1.5%], and msr(A) [27%]), trimethoprim (dfrD [65.7%]), and tetracyclines (tet(M) [41.6%], tet(S) [8%], and int-Tn [26.3%]). ERIC-PCR confirmed that the strains were genetically diverse and heterogeneous. A total of 137 isolated L. monocytogenes strains were classified into 22 distinct ERIC-PCR groups (A–V). Among them, ERIC E (10.2%) was the most prevalent group. These results indicated that environment and milking equipment served as reservoirs and potential transmission ways of virulent and multidrug-resistant L. monocytogenes to dairy animals, consequently posing threats to public health. Silage is the main environmental source of prevalent genotypes on all three farms. Therefore, hygienic measures at the farm level should be developed and implemented to reduce L. monocytogenes transmission inside dairy cattle farms.

Determining the Factors Affecting 305-Day Milk Yield of Dairy Cows with Regression Tree

The purpose of this study was to determine the factors affecting the 305-day milk yield of dairy cattle by using Regression Tree Analysis (RTA). The data set of this study consisted of 8 different cattle breeds grown in Turkey. Breed (B), Province (P), Lactation Length (LL), Service Period (SP), Dry Period (DP), Parity (PR), Calving Year (CY), Calving Age (CA) and Calving Month (CM) were used to predict the 305-day milk yield. Results of RTM showed that the usage of this method might be appropriate for determining the important factors that would be able to affect the 305-day milk yield (R2=71.3%). It was seen that the most important factors affecting the 305-day milk yield were the Breed, Lactation Length, Province, and Parity. Therefore, those selected factors were more efficient than the others in predicting the 305-day milk yield. RTA results also indicated that the lowest milk yield was estimated for Jersey, Jersey Crossbred, and Yerli Kara. Among the highest 305-day milk yield cows, the milk yield estimates of the cows in the second, third, fourth, fifth, and the sixth parities were found significantly higher than that of the cows in the first and seventh parities.

Ensiling characteristics of total mixed ration prepared with local feed resources in Mozambique and their effects on nutrition value and milk production in Jersey dairy cattle.

To effectively utilize total mixed ration (TMR) prepared with locally available feed resources, we studied the nutritional value and milk production in Jersey dairy cattle fed a local general diet (LGD) and fermented TMR in Mozambique. Ten head of Jersey dairy cattle with 337±19.8kg body weight, aged 3-4years in mid location were used in this study. The LGD diet was designed following the general feeding method of local smallholding farms; it contained native grass, Napier grass, wheat bran, and mineral-vitamin mix. Fermented TMR was prepared using Napier grass, corn bran, wheat bran, formula feed, and mineral-vitamin mix. Fermented TMR was preserved as good quality, with a relatively low pH and high lactic acid content. Compared to LGD, fermented TMR significantly improved the dry matter intake and digestibility in dairy cattle. Milk yield was significantly higher in dairy cattle fed with TMR than in those fed with LGD, by 3.75L/d; milk quality was not significantly different between treatments. The results confirmed that LGD had a low dry matter intake and milk yield, and fermented TMR prepared with local feed resources can attain good quality and improve milk yield in dairy cattle in Mozambique.

228 ASAS-EAAP Exchange Speaker Talk: Big data and the development of resilience indicators for animal breeding

Abstract In their lifetime, animals experience various environmental perturbations, such as heat stress, a disease or a change in feed, which require a response. Animals differ in their capacity to respond to various perturbations; this is called resilience, which is the capacity of animals to be minimally affected by perturbations or to rapidly return to the state before exposure to perturbations. The main obstacle in research on genetics of resilience is how to define and quantify resilience. Big data offers great opportunities because longitudinal profiles of animals, such as feed intake, body weight, milk yield or egg production, contain information about how animals respond to perturbations. The objectives of our research were to define resilience indicators and estimate heritable variation in resilience indicators and to estimate associations with existing health and longevity traits to assess the utility of resilience indicators to improve resilience by breeding. The resilience indicators studied were log-transformed variance of deviations (LnVar), lag-1 autocorrelation (Auto) of deviations and skewness of deviations (Skew) based on daily milk yield in dairy cattle and four-weekly body weight measures in laying hens. In dairy cattle, we estimated a heritability of 0.20–0.24 for LnVar, a heritability of 0.08–0.10 for Auto, and a heritability of 0.01 for Skew. The strongest genetic correlations between a resilience indicator and existing health and longevity traits were found for LnVar with udder health (-0.22 to -0.33), ketosis (-0.27 to -0.33) and longevity (-0.29 to -0.34). In laying hens, we estimated similar heritabilities for the three resilience indicators: 0.10 for LnVar, 0.11 for Auto, and 0.09 for Skew. We found predictive value of LnVar breeding values for lesion scores after challenge with an E-coli infection. These results show that especially the variance of deviations is a promising resilience indicator to improve resilience and health in animals by genetic selection.

The effect of body condition score on nutritional diseases and milk yield in dairy cattle

The purpose of this study is to examine the effects of body condition score (BCS) on nutritional diseases and milk yield in dairy cattle. Fifty-nine randomly selected Holstein Friesian cattle, lactation numbers 3-6, were used in this study from a total of 350 dairy cattle in the establishment. All of the cows in the study were fed with the same total mixed ration (TMR), and BSC was determined by inspection and palpation in the first 5 days after calving. The cows were separated into two groups according to their BCS score as BCS ≤ 3 and BCS > 3, and Group 1 contained 36 cows (BCS ≤ 3), while Group 2 contained 23 cows (BCS > 3). One-month, 3-month, and 305-day milk yields and nutritional diseases as observed until postpartum day 35 have been determined in this study. Moreover, TMR analysis has been performed. As a result, the 1-month, 3-month, and 305-day milk yields were determined in Group 1 (BCS ≤ 3) and Group 2 (BCS > 3), and no difference was determined between the groups (P > 0.05).

Different aspects of lactation persistency in dairy cows

Lactation persistency (cow’s ability to maintain milk production after reaching its peak) is a very important economic characteristic in the dairy cattle production system. Different definition and functions for describing and measuring of this trait were proposed by researchers. The random regression model using Legendre polynomial was one of the common and effective methodologies for evaluation of persistency in the last decade. Several factors affecting persistency such as different characteristics of lactation curve, environment factors, reproduction traits and health status of the dairy cow. Based on different studies the heritability of this trait was low to medium and negative or positive amount of genetic correlation between persistency and total milk yield in dairy cattle is attributed to persistency measures and method of data analysis. Persistency is related with low and later peak yield and selecting cows for peak yield will improve persistency and lactation curve traits. Analysis of relationships between persistency and other functional traits show signs that genetic improvement for persistency is possible and favorable. Different aspects and relationships of persistency with various lactation and other functional traits in dairy cows are reviewed in this article.

The Effect of Hoof Trimming on Milk Yield in Dairy Cattle

Hoof trimming is necessary for conformation and health of cattle. It is performed to prevent hoof lesions and maintenance the symmetry and shape of claw. At the same time it is a stress factor in dairy cattle. The aim of the study was to investigate the stress effects of hoof trimming on milk yield in healthy dairy cattle. Twenty Simmental dairy cattle were used as material. Functional hoof trimming was performed for all cattle. Dairy milk yield was measured before and after hoof trimming period. There were personal increases and decreases of milk yield recorded in animals. However, these increase and decrease were not statistically significant. As a result of this study hoof trimming is necessary for claw health and prevention for foot diseases. In healthy dairy cattle it causes stress and to decreases in milk yield. On the other hand the hoof trimming time, environmental factors such as flooring system and management style, and the animal related factors such as lactation period and stage, number of milking, breed and age affect the milk yield with hoof trimming positively or negatively. Keywords : Cattle, Dairy, Hoof, Milk, Simmental DOI : 10.7176/JSTR/5-5-07

Dietary supplementation of Scutellaria baicalensis extract during early lactation decreases milk somatic cells and increases whole lactation milk yield in dairy cattle.

Systemic inflammation is common in early lactation dairy cows and is associated with decreased milk production. The Scutellaria baicalensis plant contains flavonoids with anti-inflammatory and anti-oxidative properties, which may counteract the inflammatory state in early lactation dairy cows. The objective of this experiment was to determine whether Scutellaria baicalensis extract (SBE), a source of bioactive flavonoids, would alter the adaptation to lactation. Multiparous Holstein cows (n = 122) were used in a randomized block design to determine the effect of short-term and long-term postpartum administration of SBE on 305-d milk yield, 120-d milk component yield, and early lactation milk markers of inflammation and metabolic function. Treatments were 1) control, 2) short term (5-d) administration of the SBE (SBE5), and 3) long term (60-d) administration of the SBE (SBE60). Treatments were included in a treatment pellet that was identical to a control pellet in ingredient source and composition except for the extract (10 g/d SBE providing 3.3 g/d of the flavonoid baicalin), both provided via an automated milking system beginning on d 1 of lactation. Milk samples were collected on d 1, 3, and once during d 5–12 of lactation, followed by weekly sampling until 120 days in milk (DIM). Milk samples collected in the first 2 wk were used for biomarker analysis (haptoglobin, β-hydroxybutyrate [BHB], and glucose-6-phosphate [G6P]), and all samples were used for composition analysis. Cows were body condition scored every 2 wk prepartum and postpartum. Milk production, programmed pellet allocation, and actual provision of both pelleted feeds were recorded daily. Treatment effects were evaluated by contrasts between control and SBE5 and control and SBE60 for both the treatment (TP; wk 1–9) and carryover periods (CP; wk 10–37). Total pellet offered was greater for SBE60 in both the TP (P < 0.01) and CP (P = 0.02) but was not different for SBE5 during either period (P ≥ 0.13). No treatment effects were observed for body condition score (BCS), milk haptoglobin, BHB, or G6P. SBE5 did not alter milk yield or milk components. SBE60 increased whole-lactation milk yield by 1,419 kg (13%; P = 0.03). SBE60 increased milk lactose and fat yields (P ≤ 0.04) and tended to increase milk protein yield (P = 0.09) during TP, and each increased during CP (P ≤ 0.04). Somatic cell count decreased by 10% in SBE60 during TP (P = 0.02) but not CP (P = 0.13). Mastitis incidence tended to differ by treatment, being lesser for both SBE5 and SBE60 vs. control (14 and 15% vs. 33%). SBE supplementation did not impact time to pregnancy or hazard of leaving the herd. In conclusion, despite no detected treatment effects on BCS or milk biomarkers of inflammation and metabolic status, supplementation of postpartum dairy cows with Scutellaria baicalensis extract for 60 d was effective at increasing whole lactation milk yield.

Genetic parameters for endocrine and traditional fertility traits, hyperketonemia and milk yield in dairy cattle

High-yielding cows may suffer from negative energy balance during early lactation, which can lead to ketosis and delayed ability of returning to cyclicity after calving. Fast recovery after calving is essential when breeding for improved fertility. Traditionally used fertility traits, such as the interval from calving to first insemination (CFI), have low heritabilities and are highly influenced by management decisions. Herd Navigator™ management program samples and analyses milk progesterone and β-hydroxybutyrate (BHB) automatically during milking. In this study, the genetic parameters of endocrine fertility traits (measured from milk progesterone) and hyperketonemia (measured from milk BHB) in early lactation were evaluated and compared with traditional fertility traits (CFI, interval from calving to the last insemination and interval from first to last insemination) and the milk yield in red dairy cattle herds in Finland. Data included observations from 14 farms from 2014 to 2017. Data were analyzed with linear animal models using DMU software and analyses were done for first parity cows. Heritability estimates for traditional fertility traits were low and varied between 0.03 and 0.07. Estimated heritabilities for endocrine fertility traits (interval from calving to the first heat (CFH) and commencement of luteal activity (C-LA)) were higher than for traditional fertility traits (0.19 to 0.33). Five slightly different hyperketonemia traits divided into two or three classes were studied. Linear model heritability estimates for hyperketonemia traits were low, however, when the threshold model was used for binary traits the estimates became slightly higher (0.07 to 0.15). Genetic correlation between CFH and C-LA for first parity cows was high (0.97) as expected since traits are quite similar. Moderate genetic correlations (0.47 to 0.52) were found between the endocrine fertility traits and early lactation milk yield. Results suggest that the data on endocrine fertility traits measured by automatic systems is a promising tool for improving fertility, specifically when more data is available. For hyperketonemia traits, dividing values into three classes instead of two seemed to work better. Based on the current study and previous studies, where higher heritabilities have been found for milk BHB traits than for clinical ketosis, milk BHB traits are a promising indicator trait for resistance to ketosis and should be studied more. It is important that this kind of data from automatic devices is made available to recording and breeding organizations in the future.

The impact of genetic and non-genetic factors on somatic cell count as a monitor of udder health in Slovak Simmental dairy cows

Received: 2018-05-18 | Accepted: 2018-05-22 | Available online: 2018-11-26 https://doi.org/10.15414/afz.2018.21.04.166-168 The aim of study was to evaluate the impact of genetic and non-genetic factors on somatic cells count in Slovak Simmental dairy cows in period 2009 to 2013. We observed subsequent results in dairy cows of 55 822 Slovak Simmental cattle. Data were analysed using the SAS and linear model with fixed effects of herd, years and months controls, sire, breeding type. The results of somatic cells count during the years 2009 and 2013 were as follows: the highest number of samples was analysed during 2010 (n = 288 215), where the average count was 560.48*10 3 · ml -1 . The lowest average value of somatic cells count was of amount of 535.93*10 3 · ml -1 (n = 280 732) in 2009.The linear model represents coefficient determination R 2 = 0.038296 % (P<0.001) for SCC with all fixed effects. According to the analyses by the effects on SCC the highest effect was the effect of herd R 2 = 0.021625, then effect of sire R 2 = 0.015075. These effects were highly statistically significant (P<0.001). Correlation coefficients among milk in kg, fat, protein in % with somatic cells count were r = -0.12918, r = 0.04166 and r = 0.11423. These coefficients were highly statistically significant (P<0.001). Keywords: dairy cows, milk production, Slovak Simmental cattle, somatic cells count and coefficient of determination References Alhussien M.N., Dang A.K. (2018) Milk somatic cells, factors influencing their release, future prospects, and practical utility in dairy animals: An overview. Veterinary World, 11 (5), 562-577. DOI: https://dx.doi.org/10.14202/vetworld.2018.562-577 Boro, P., Naha, B., Prakash, Ch., Madkar, A., Kumar, N., Kumari, A., Prakash Channa, G. (2016) Genetic and non-genetic factors affecting milk composition in dairy cows. 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Saravanan, R., Das, D. N., De, S., Panneerselvam, S. (2015) Effect of season and parity on somatic cell count across zebu and crossbred cattle population. Indian J. Anim. Res., 49, 383-387. DOI: https://dx.doi.org/10.5958/0976-0555.2015.00127.2 SAS User’s Guide 2002-2003. Version 9.3 (TS1M3). SAS Institute. Inc., Carry. NC. USA. Savic, N. R., Mikulec, D. P., Radovanovic, R. S. (2017) Somatic Cell Counts in Bulk Milk and their Importance for Milk Processing. In: IOP Conference Series: Earth and Environmental Science, 85, p012085. Sharif, A., Muhammad, G. (2008) Somatic cell count as an indicator of udder health status under Modern dairy production: a review. Pakistan Vet. J., 28 (4), 194-200. Souza, G. N., Brito, Jose R. F., Brito, Maria A. V. P., Moreira, Elvio C., da Silva, Marcos V. G. B.(2005) Factors affecting somatic cell counts (SCC) in Brazilian dairy cows. In: Animals and environment. 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The effect of alfalfa (Medicago sativa) silage chop length and inclusion rate within a total mixed ration on the ability of lactating dairy cows to cope with a short-term feed withholding and refeeding challenge

The objectives of the study were (1) to test whether 6 h of feed deprivation followed by refeeding induces an acidosis challenge in dairy cattle and (2) to quantify the acidosis challenge mitigation potential of increased alfalfa silage concentration in the diet. Alfalfa silage constituted either 25 or 75% of forage dry matter (DM) replacing corn silage [low (LA) or high alfalfa (HA)] and was chopped to either 14 or 19 mm theoretical length [short (S) or long (L)]. Dietary treatments LAS, LAL, HAS, or HAL were offered to 4 rumen-cannulated Holstein dairy cattle (161 d in milk; 5th or 6th parity) in a 4 × 4 Latin square design study with 21-d periods. Starch concentration was 69 g/kg of DM higher for LA diets than HA diets. Feed was withheld for 6 h followed by ad libitum refeeding on d 18 of each period. Measurements of DM intake, milk yield and composition, rumen pH, and eating and rumination behavior were taken on 1 baseline day, the challenge day, and 2 further recovery days. After refeeding, rumen pH was reduced in cows fed LA diets but not HA diets. Feeding LAL resulted in the greatest subclinical acidosis risk (pH <5.8 for 355 min on the first recovery day). Animals fed LA produced 4.4 L less milk on the challenge day in comparison to baseline. It was concluded that short-term feed deprivation detrimentally affected rumen health and milk yield in dairy cattle normally fed ad libitum, but had no effect on DM intake or milk composition. Feeding alfalfa silage in place of corn silage mitigated acidosis risk due to interrupted feed supply, likely due to a combination of lower starch concentration in HA diets, greater effective fiber concentration, and higher buffering capacity of alfalfa relative to corn silage.

508 Trend for diurnal temperature variation and relative humidity and their impact on milk yield of dairy cattle in tropical climates

508 Trend for diurnal temperature variation and relative humidity and their impact on milk yield of dairy cattle in tropical climates

Applicability of Pediococcus strains for fermentation of cereal bran and its influence on the milk yield of dairy cattle

Applicability of Pediococcus strains for fermentation of cereal bran and its influence on the milk yield of dairy cattle

The effect of varying proportion and chop length of lucerne silage in a maize silage-based total mixed ration on diet digestibility and milk yield in dairy cattle

The objective was to assess the effects of inclusion rate and chop length of lucerne silage, when fed in a total mixed ration (TMR), on milk yield, dry matter (DM) intake (DMI) and digestion in dairy cows. Diets were formulated to contain a 50 : 50 ratio of forage : concentrate (DM basis) and to be isonitrogenous (170 g/kg CP). The forage portion of the offered diets was comprised of maize and lucerne silage in proportions (DM basis) of either 25 : 75 (high Lucerne (HL)) or 75 : 25 (low lucerne (LL)). Lucerne was harvested and conserved as silage at either a long (L) or short (S) chop length. These variables were combined in a 2×2 factorial arrangement to give four treatments (HLL, HLS, LLL, LLS) which were fed in a Latin square design study to Holstein dairy cows in two separate experiments. In total, 16 and 8 multiparous, mid-lactation cows were used in experiments 1 and 2, respectively. To ensure sufficient silage for both experiments, different cuts of lucerne silage (taken from the same sward) were used for each experiment: first cut for experiment 1 (which was of poorer quality) and second cut for experiment 2. Dry matter intake, milk yield and milk composition where measured in both experiments, and total tract digestibility and nitrogen (N) balance were assessed using four cows in experiment 2. In experiment 1, cows fed LL had increased DMI (+3.2 kg/day), compared with those fed HL. In contrast, there was no difference in DMI due to lucerne silage inclusion rate in experiment 2. A reduction in milk yield was observed with the HL treatment in both experiment 1 and 2 (−3.0 and −2.9 kg/day, respectively). The HL diet had reduced digestibility of DM and organic matter (OM) (−3% and −4%, respectively), and also reduced the efficiency of intake N conversion into milk N (−4%). The S chop length increased total tract digestibility of DM and OM (both +4%), regardless of inclusion rate. Inclusion of lucerne silage at 25% of forage DM increased milk yield relative to 75% inclusion, but a S chop length partially mitigated adverse effects of HL on DMI and milk yield in experiment 1 and on DM digestibility in experiment 2.

GWAS in practical cattle breeding in Czech Republic, single step method, genetic progress

Development of genetic evaluation of animals is permanent process. It was going from estimated breeding value (EBV) calculated by CC-test, across a BLUP – animal model and RR-TDM, to the genomic enhanced breeding value (GEBV) using genetic markers. Methods of genetic evaluation become a part of marketing strategies of insemination companies. Therefore all countries and association of breeders seek to be compatible with others. Now we are in a period of massive global implementation of genomic evaluation, which combines traditional BLUP with huge quantity of genetic SNP markers. Multi-step procedures are now usual in practice, which work with deregressed proofs. Development of methods attained to the single-step procedure (ssGBLUP) which overcomes some difficulties of previous methods, improves reliabilities of evaluation and compares all animals, genotyped and ungenotyped, in entire nation-wide population. Genomic evaluation influence above all young genotyped animals. In Czech Republic single-step procedure is routinely used for national evaluation of milk, linear type traits, reproduction and longevity. GEBVs are accompanied by genomic reliabilities. Genetic trends over last 20 years are in some traits different for genomic evaluation compared to traditional BLUP evaluation, although input data and genetic parameters (heritability) are the same and genotyped animals were only small proportion from entire evaluated population. Differences in genetic trends increase mainly in new batches of animals. Reason of it could be in the changed variability of breeding values and “genomic correction” of relationship between animals, which is expanded from genotyped animals to others individuals in a population. Keywords: genomic breeding value, single-step, genomic relationship, genetic trend, SNP References Bauer, J. et al. (2014) Approximation of the reliability of single-step genomic breeding values for dairy cattle in the Czech Republic. Anim. Sci. 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