Milk Fat Yield Research Articles

Influence of peripartum dietary supplementation of choline and fat in protected form on production performance of Gir cows

In this experiment, the effects of supplementing choline and fat in rumen protected form during peripartum period on feed intake, milk production and composition of Gir cows were studied. Twenty four Gir cows of 1st to 3rd parity were used from 30 days pre-partum through 60 days post-partum and randomly assigned to four equal treatment groups (n=6) on the basis of their parity, body weight and previous lactation yield. Control diet was fed to cows in group T1 (control). Additionally, rumen protected choline (RPC) @45 g/d in group T2; rumen protected fat (RPF) 80 g/d in group T3 and RPC @45 g/d + RPF @80 g/d in group T4 were supplemented along with control diet. The treatments significantly affected dry mater intake (DMI) and milk production of cows. DMI was increased in the cows fed with RPC as compared to control. Milk yield, 4% fat-corrected milk, solid-corrected milk and energy- corrected milk were higher in the cows fed with RPC and RPF alone or in combination, as compared to control. No synergistic effect was observed with these supplements on DMI or milk production. None of these supplements influenced the milk composition significantly, however yield of milk fat, protein and lactose were higher in all the nutrient supplemented cows compared to control. Net return over feed cost was higher in supplemented cows compared to control. Results indicated that supplementation of RPC or RPF can improve feed intake and productive performance of Gir cows for overall economic benefits.

Abomasal infusion of branched-chain amino acids or branched-chain keto-acids alter lactation performance and liver triglycerides in fresh cows

BackgroundDairy cows are at high risk of fatty liver disease in early lactation, but current preventative measures are not always effective. Cows with fatty liver have lower circulating branched-chain amino acid (BCAA) concentrations whereas cows with high circulating BCAA levels have low liver triglyceride (TG). Our objective was to determine the impact of BCAA and their corresponding ketoacids (branched-chain ketoacids, BCKA) on production performance and liver TG accumulation in Holstein cows in the first 3 weeks postpartum.MethodsThirty-six multiparous Holstein cows were used in a randomized block design experiment. Cows were abomasally infused for the first 21 d postpartum with solutions of 1) saline (CON, n = 12); 2) BCA (67 g valine, 50 g leucine, and 34 g isoleucine, n = 12); and 3) BCK (77 g 2-ketovaline calcium salt, 57 g 2-ketoleucine calcium salt, and 39 g 2-ketoisoleucine calcium salt, n = 12). All cows received the same diet. Treatment effects were determined using PROC GLIMMIX in SAS.ResultsNo differences were detected for body weight, body condition score, or dry matter intake averaged over the first 21 d postpartum. Cows receiving BCK had significantly lower liver TG concentrations compared to CON (6.60% vs. 4.77%, standard error of the mean (SEM) 0.49) during the first 3 weeks of lactation. Infusion of BCA increased milk yield (39.5 vs. 35.3 kg/d, SEM 1.8), milk fat yield (2.10 vs. 1.69 kg/d, SEM 0.08), and lactose yield (2.11 vs. 1.67 kg/d, SEM 0.07) compared with CON. Compared to CON, cows receiving BCA had lower plasma glucose (55.0 vs. 59.2 mg/dL, SEM 0.86) but higher β-hydroxybutyrate (9.17 vs. 6.00 mg/dL, SEM 0.80).ConclusionsOverall, BCAA supplementation in this study improved milk production, whereas BCKA supplementation reduced TG accumulation in the liver of fresh cows.Graphical

Effects of dietary palmitic acid and oleic acid ratio on milk production, nutrient digestibility, blood metabolites, and milk fatty acid profile of lactating dairy cows

Adequate energy supply is a crucial factor for maintaining the production performance in early lactating cows. Adding fatty acids to diets can improve energy supply, while the effect could be related to the chain length and degree of saturation of fatty acids. This study was conducted to evaluate the effect of different ratios of palmitic acid (C16:0) to oleic acid (cis-9 C18:1) on the production performance, nutrient digestibility, blood metabolites and milk fatty acids profile in early lactating dairy cows. Seventy-two multiparous Holstein cows (63.5 ± 2.61 d in milk) blocked by parity (2.39 ± 0.20), body weight (668.3 ± 20.1 kg), body condition score (3.29 ± 0.06), and milk yield (47.9 ± 1.63 kg) were used in a completely randomized design. Cows were divided into 3 groups with 24 cows in every group. Cows in 3 treatments were provided iso-energy and iso-nitrogen diets, whereas the C16:0 to cis-9 C18:1 ratio was different: (1) 90.9% C16:0 + 9.1% cis-9 C18:1 (90.9:9.1); (2) 79.5% C16:0 + 20.5% cis-9 C18:1 (79.5:20.5); (3) 72.7% C16:0 + 27.3% cis-9 C18:1 (72.7:27.3). Fatty acids were added at 1.3% in dry matter basis. Although the dry matter intake fat-corrected milk yield and energy-corrected milk yield were not affected, the milk yield, milk protein yield and feed efficiency increased linearly with the increasing of cis-9 C18:1 ratio. The milk protein percentage and milk fat yield did not differ among treatments, whereas the milk fat percentage tended to decrease linearly with the increasing of cis-9 C18:1 ratio. The lactose yield increased linearly and lactose percentage tended to increase linearly with increasing cis-9 C18:1 ratio, whereas the percentage of milk total solids and somatic cell count decreased linearly. Though the changes of body condition score were not affected by treatments, the body weight loss decreased linearly with the increasing of cis-9 C18:1 ratio. The effect of treatment on nutrient digestibility was limited, except a linear increase in ether extract and neutral detergent fiber digestibility with the increasing of cis-9 C18:1 ratio. There was a linear increase in the concentrations of plasma glucose, whereas the triglyceride and nonesterified fatty acid concentration decreased linearly with the increasing of cis-9 C18:1 ratio. As the cis-9 C18:1 ratio increased, the concentration of de novo fatty acids decreased quadratically, while the mixed and preformed fatty acids increased linearly. In conclusion, increasing cis-9 C18:1 ratio could increase production performance and decrease body weight loss by increasing nutrient digestibility, and the ratio had the most powerful beneficial effect on early lactating cows suggested by 72.7:27.3.

Influence of genetic factors on productive traits of firstcalf heifers

The objects for the research were Holsteinized fi rst-calf heifers-daughters of sires with blood of 90 % or more of Holstein breed. In order to carry out the research three groups of first-calf heifers per 30 heads in each were formed. The 1st group included daughters of the sire Privelezh, the 2nd group included the daughters of the sire Alt Pilsner, and the 3rd group included the daughters of the sire Alt Tyson. The infl uence of sires on the productive traits of Holsteinized fi rst-calf heifers of Black-and-White breed was assessed under the conditions of the Petrovsky Agricultural Production Complex in the Bashmakovsky district of Penza region. It was revealed as a result of the research that the highest milk yield for 305 days of lactation was shown by the daughters of the sire Privelezh, which amounted to 9398 kg of milk and had a statistically signifi cant diff erence with the daughters of the sire Alt Pilsner – 3657 kg (Р > 0,999) and with the daughters of the sire Alt Tyson – 3542 kg (Р > 0,999). In terms of qualitative traits of milk productivity, the highest indicators were for fi rst-calf heifers of the 2nd and 3rd groups. For example, in terms of the mass fraction of fat the difference between cows of the 2nd and 1st groups was 0,16 abs.% (Р > 0,95). Diff erences were revealed between the 1st and 2nd groups by 0,04 abs.% (Р > 0,999). At the same time, due to higher milk yields animals of the 1st group exceeded their herdmates of the 2nd group in the yield of milk fat and protein by 127,92 kg (Р > 0,95) and 111,67 kg (Р > 0,999); 3rd group by 128,90 kg (Р > 0,999) and 109,08 kg (Р > 0,999), respectively. First-calf heifers of the 3rd group had the highest live weight (568,7 kg), the diff erence with their herdmates of the 1st group was 57,2 kg (Р > 0,999). Animals of the 2nd group exceeded the first group by 53,0 kg (Р > 0,999). The greatest variability in milk yield over 305 days of lactation was characterized by the 3rd group of cows (Cv=19,83 %) vice versa 17,45 and 18,92 % in the 1st and 2nd groups. First-calf heifers of the 1st group were distinguished by the greatest effi ciency and usefulness, although no significant differences were found between the groups. For example, per 1 kg of live weight, the Biological efficiency of a cow coefficient was 445,45 and the Cow biological f usefulness coefficient was 306,23.

Продуктивность коров при разной комбинации линий

The purpose of the study was to study the milk productivity of cows with different combinations of lines. The object of the study were first-calf cows of the black-and-white breed of the line Vis Back Aidiala 101341, Reflection Soveringa 198998, Montvik Chiefteina 95679. Cows obtained by intraline selection of the Aidial line have a high level of milk productivity, with milk yield of 5571 kg of milk, milk fat yield of 226 kg and protein yield of 171 kg, while significantly (P<0.05-0.01) superior to first-calf heifers, belonging to the Sovering line for 102 kg, 4 kg of fat and 4 kg of protein, and to the Chieftain line - for 259 kg of milk, 16 kg of fat and 11 kg of protein, respectively. When crossing the Ideal-Sovering lines, the highest milk yield is observed (5667 kg), with good milk fat content (4.01 %), high yield of milk fat (227 kg) and milk protein (172 kg). With the reverse cross Sovering-Idial, slightly lower milk productivity rates were obtained. When using bulls of the Aidial line on cows of the Governer line, high milk fat content (4.07 %) and milk fat yield (228 kg) were obtained, with average values of milk yield (5596 kg), protein mass fraction (3.01 %) and its yield (168 kg). Unsuccessful combinations of lines in both forward and reverse directions are crosses of the Idial and Chieftain lines. The descendants of such combinations have the lowest milk productivity. Thus, the use of line manufacturers R. Sovering and V.B. Idiala, both with intraline selection and interline combination, gives the best milk productivity indicators. Consequently, it is necessary to evaluate bulls according to the compatibility of lines; this has a great influence on the productivity of the offspring, since sires of the same line, when inseminating cows of the same lines, produce offspring of different productivity.

Effects of betaine supplementation on dry matter intake, milk characteristics, plasma non-esterified fatty acids, and β-hydroxybutyric acid in dairy cattle: a meta-analysis.

Betaine supplementation in dairy cattle has gained attention due to its potential benefits to production and health as a methyl donor, which can play a crucial role in the metabolism of dairy cows. The objective of the current meta-analysis was to quantify the effects of betaine supplementation on milk production, composition, β-hydroxybutyric acid (BHBA), and non-esterified fatty acids (NEFA). A systematic literature search was carried out, all relevant studies were retrieved, and the meta-analysis was carried out. The mean difference (MD) for dry matter intake (DMI) using the random-effects model was 0.499kg/d (P < 0.0001). The subgroup analysis indicated that supplementing betaine in heat-stressed cows increased DMI by 0.584kg/d (P < 0.001), while in cows not exposed to heat stress, DMI was increased by 0.381kg/d (P = 0.007). The energy-corrected milk (ECM) increased by 1.36kg/d (P < 0.0001). The milk fat yield was significantly increased in betaine-supplemented cows (MD = 0.040kg/d, 95% CI = 0.015 to 0.065). The milk protein yield (kg/d) (MD = 0.014, P = 0.138) was increased (MD = 0.035, P = 0.0005) by betaine supplementation. The lactose yield (kg/d) was also significantly higher (MD = 0.055, P = 0.020) in betaine-supplemented cows. The standardized mean difference (SMD) for NEFA (SMD = - 0.447, 95% CI = - 1.029 to 0.135, P = 0.114) and BHBA (SMD = - 0.130, 95% CI = - 0.491 to 0.234). In conclusion, the findings from this meta-analysis suggest that betaine supplementation positively influences DMI, ECM, milk fat yield, milk lactose yield, and milk protein yield. Subgroup analysis further indicated that the positive effects on DMI are greater in heat-stressed cows compared to those not exposed to heat stress. The analysis did not find significant effects on the levels of NEFA or BHBA, suggesting that betaine supplementation may not directly influence these metabolic parameters.

Influence of feed mixtures on the productivity of cows and chemical composition of milk during the period of increasing the milk yield

There is a wide variety of climatic zones in the huge territories of our country, which require special approaches to feeding and housing of animals. Providing animals with adequate and rationed feeding under the conditions of the Northern Trans-Urals and Siberia is a difficult task due to the long stall period. The purpose of the work was to determine the infl uence of diff erent methods of feed distribution such as separate and feed mixture on milk productivity of cows and the chemical composition of milk during the period of increasing the milk yield. It was found that the milk yield of natural fat content during the fi rst 100 days of lactation in the experimental group of cows was 325 kg or 10,21 % higher than in the control group. Milk fat yield was obtained from the cows of the experimental group by 16,5 kg or 13,80 % more compared to the animals of the control group. The mass fraction of fat in the milk of cows in the experimental group was higher by 0,12 abs.%. However, the difference between groups in milk yield, milk fat content and milk fat yield was statistically insignificant. The difference in the content of protein, ash, calcium and phosphorus in the milk of the experimental animals was also insignificant, although there was some advantage in the content of these indicators in the experimental group, where the feed was fed in the form of the feed mixture. It was found when analyzing economic indicators that for cows in the control group the prime-cost of 1 kg of milk was 16,49 rubles, which was by 1,53 rubles or 3,91 % more than in the experimental group. At the same time, the level of profitability of milk production in the experimental group was higher than 12,66 abs.% compared to the control group.

Productivity and milk quality of Saanen and Anglo- Nubian breeds of goats under the conditions of the Lower Volga region

Prospects for the development of dairy goat farming and goat milk production in many countries of the world, including Russia, are directly related to the dietary and healing properties of the product. An urgent problem is the comparative assessment of the adaptive and productive traits of dairy goats of imported selection under various ecological and climatic conditions of Russia, including the conditions of the sharp continental climate of the Lower Volga region. The purpose of the work was to give a comparative assessment of the eff ectiveness of breeding lactating goats of Saanen and AngloNubian breeds of imported selection under the conditions of the sharp continental climate of the Lower Volga region. The object of research was imported dairy goats. Two groups of female goats of Saanen and Anglo-Nubian breeds of the fi rst lactation of 10 heads in each were formed, taking into account their live weight, age of insemination and origin. The duration of the scientific and farm experiment was 210 days.Consistently high milk yield was found in goats of Saanen breed compared with the milk yield of their herdmates of Anglo-Nubian breed. The signifi cant diff erence in milk yield in favor of Saanen goats by months ranged from 13,24 to 16,51 % (p &lt; 0,05). In general, during lactation the superiority of Saanen goats over their Anglo-Nubian herdmates in terms of milk yield was 61,2 kg or 15,75 %. A comparative analysis of quality indicators revealed a significant superiority of milk from goats of Anglo-Nubian breed such as in the mass fraction of fat by 1,48 abs.% (p &lt; 0,05), in the mass fraction of protein by 0,24 abs.% (p &lt; 0,05), in terms of milk fat yield by 3,15 kg (p &lt; 0,05). It was found as a result that in the production of milk from goats of Anglo-Nubian breed, the level of profitability of milk with basic fat content (3,5 %) was higher by 27,78 abs.% compared with herdmates of Saanen breed.

MILK PRODUCTIVITY OF COWS OF THE UKRAINIAN RED-AND-WHITE DAIRY BREED DEPENDS ON THE ORIGIN AND COMPATIBILITY OF THE BULLS

We studied the effectiveness of the bulls selection to the cows of the Ukrainian Red-and-White dairy breed (n = 490 mother-daughter pairs) different bloodlines and related groups. The level of milk productivity of first-borns cows (n = 490 mother-daughter pairs) for 305 days of the first lactation, obtained as a result of the compatibility of the bulls. The parents of the first-borns cows were four breeding bulls (bloodline Regal 352882, RG Valiant 1650414 and R. Sovereign 198998) of the Ukrainian Red-and-White dairy breed and one bull (Jornado Red 114386106, RG Chief 1427381) of the Holstein breed, and their mothers – from 11 bulls of three origin bloodlines (Dynemik 359742, Leader 1926780 and Hanover 1629391) and 4 related groups. A total of 29 combinations of interbloodline selection were investigated. The highest level of milk productivity was characterized by the daughters of bull Viter 4444 of the bloodline Regal 352882 (7191.5 ± 75.90), Jornado Red 114386106 of the Holstein breed of foreign selection, which belonged to the related group Chief 1427381 (the milk yield for 305 days of the first lactation was 7188.7 ± 31.05 kg), and Artek 344 related group Valiant 1650414 (the yield for 305 days of the first lactation was 7052.5 ± 75.51 kg). A statistically significant difference was established between milk yield indicators for 305 days of the first lactation between the groups of cows of the bull Jornado Red (related group Chief 14273381) and Luchnov 471 (r. g. R. Sovereign 198998) – +380 kg (td = 4.22 p &lt; 0.001) in favor Jornado Red. Between cows of the bull Viter 4444 (bloodline Regal 352882) and Luchnov 471 (R. Sovereign 198998) – +383 kg (td = 3.38 p &lt; 0.001) in favor of Viter 4444. Animals of the bulls Kanzler and Viter 4444 have the highest fat content in milk (3.71%), and cows of the related groups Valiant 1650414 characterized by the lowest fat content in milk (3.68%). A statistically significant difference was established between the amount of total milk fat and protein in the milk of cows of different bulls.&#x0D; A total 20 successful combinations of bulls were found, the first-borns cows of which were characterized by an increased milk yield on average across all successful compatibility by +96 kg (1.5%), milk fat yield – by +6,1 kg (2.3%) and total protein – by +5.3 kg (2.3%) from the average level of phenotypic manifestation of milk productivity traits of the daughters of all 5 evaluated bulls. The increasing of daughters milk yield of some successful combinations was from +42 kg (0.6%, sire Jornado 114386106 RG Chief 1427381) up to +296 kg (4.1%, sire Viter 4444,), milk fat from +2 kg (0.7%, sire Artek 344, RG Valiant) up to +8 kg (3%, sire Viter 4444) and protein from +1 kg (0.4%, sire Artek 344) up to +12 kg (5%, sire Viter 4444). The data, which we received, confirm the influence of the origin of cows by father on the level of their milk productivity and the high combining ability of individual improver bulls with the mothers of other genealogical formations.

THE CORRELATIVE VARIABILITY OF THE FINAL SCORE BY LINEAR CLASSIFICATION AND LIFETIME PRODUCTIVITY INDICATORS AMONG BLACK-AND-WHITE DAIRY COWS OF DIFFERENT BREEDS

A study on the correlative variability of the final score by linear classification and lifetime productivity indicators of Black-and-White Dairy cows of different breeds was conducted in the herd of the private enterprise "Burynske" in the Podlisniv branch of the Stepaniv territorial community. Foreign studies on the cows evaluation of different breeds by conformation type using the linear classification method were analyzed, which proved that the lifetime productivity indicators of animals depend on many genotypic and paratypic factors. In this direction, the existence of significant moderate and close positive correlations between the majority of linear traits and functional life of cows in the herd was established. It has also been proven that the final score level of cows by type is closely correlated with descriptive traits that significantly affect lifetime productivity indicators. According to the results of our own research, it was found that degree of the final score of first-born cows for the conformation type directly determines the variability level of indicators to the duration of use and lifetime productivity within both experimental breeds. Cows of the Holstein and Ukrainian Black-and-White dairy breeds with a rating of "very good" exceeded animals with ratings of "good plus" and "good" by indicators of duration productive use and milk productivity throughout life. Holstein cows rated "very good" were better than animals rated "good plus" and "good" in terms of lifetime milk yield and milk fat yield, respectively by 4589 and 21653 kg, and 191 and 918 kg. The final score, in the presence of a correlation with lifetime productivity indicators, can serve as a predictor of longevity, which will allow effective selection of first-born dairy cows based on the results of a linear evaluation in the first months of lactation.

ECONOMIC USEFUL AND BIOLOGICAL SIGNS IN PUREBRED AND CROSS-BRED COWS OF THE UKRAINIAN BLACK-AND-WHITE DAIRY BREED UNDER THE EFFECTS OF HIGH TEMPERATURES AND TYPES OF FEEDING

The results of studies of economically useful and biological traits in purebred (Ukrainian Black-and-White dairy breed) and cross-breed (Ukrainian Black-and-White dairy breed x Swiss) cows are given, taking into account the effect of high temperatures and types of feeding. At the same time, it was established that purebred cows exceeded crossbred cows in terms of milk yield, but were inferior to the latter in terms of milk quality (fat content, protein content). In general, the advantage in milk fat and protein yield in favor of crossbred cows, in the section of three lactations, was from 3.0 to 9.5 kg and from 2.6 to 6.4 kg, respectively.&#x0D; Along with this, the dependence of heat resistance of cows on their genotype was established. Cross-breed cows were characterized by better adaptation properties to the effects of hot weather conditions, as they had more balanced indicators of heat resistance.&#x0D; Analysis of indicators of milk productivity of cows with different types of feeding showed that the use of the same type of feeding provides an increase in milk yield per 533 kg of milk, fat content by 0.14% and protein by 0.01% compared to traditional feeding technology.

CHARACTERISTICS THE OFFSPRING OF SIRES BY LONGEVITY TRAITS OF THE HERD FOR BREEDING UKRAINIAN BLACK-AND-WHITE DAIRY BREED

Based on studies of the offspring of sires in a herd for breeding the Ukrainian Black-and-White dairy breed (UBWD), a significant influence of their heredity on the variability of longevity traits has been established. According to the duration of productive use, the variability between extreme options was 1061 days, and in terms of the number of lactations used during life, it was ‑ 2.7, with high reliability for both traits (P &lt; 0.001). The variability of longevity traits did not depend on the origin of the sires, among whom there are purebred Holsteins and bulls of domestic selection of Ukrainian Black-and-White dairy breed of different genotypes and lines. It was found that the quantity of days of productive use and the number of used lactations during the life of cows of different origins are positively correlated with indicators of productive longevity ‑ lifetime milk yield and milk fat, and milk yield per day of productive use. Variability in lifetime milk yield varied widely, from 14934 (daughters of the sire Katka 5218, Metta line, UBWD), to 33031 kg (daughters of the sire Marcellus 136057831, line P. F. A. Chief, Holstein breed), with a high reliable difference between them, which amounted to 18097 kg (P &lt; 0.001). The milk fat content of the daughters of the assessed sires also differed in significant, at a reliable level, variability within the range of 3.72–3.85% with a difference between the extreme options of 0.13% (P &lt; 0.001). Similar variability in sire offspring, regardless of origin, was observed in lifetime milk fat yield, with variation ranging from 570.5–1197.9 kg, with the highest indicator in daughters of Holstein bull Caprice 401393 and the lowest in daughters of domestic sire Katka 5218.

Pedigree base of brown Swiss cattle breed in the Smolensk region

The current state by the end of 2020of the Brown Swiss breed of cattle in pedigree farms of the Smolensk region was studied. The average milk yield in herds for the last completed lactation is 4045 – 6626 kg of milk, the yield of milk fat and protein is 158 – 268 kg and 134 – 236 kg, respectively. In the best farm of the SPK “Druzhba”, the average milk yields of cows for the highest lactation exceed 7000 kg of milk, eight animals have record results of 10016 – 11720 kg. Cows are born from fathers of high breeding value. The average milk yield mothers of fathers in herds is 9767 – 12333 kg. The average age of cows according to the last completed lactation in the studied herds is 2.3 – 3.9 lactation. The age of the first fruitful insemination in the best farm is 16.5 months. From 87.8 to 98.3% of cows belong to lines of foreign origin.

Descriptive Statistics and Genome-Wide Copy Number Analysis of Milk Production Traits of Jiangsu Chinese Holstein Cows.

Milk production traits are the most important quantitative economic traits in dairy cow production; improving the yield and quality of milk is an important way to ensure the production efficiency of the dairy industry. This study carried out a series of in-depth statistical genetics studies and molecular analyses on the Chinese Holstein cows in the Jiangsu Province, such as descriptive statistics and copy number variation analysis. A genetic correlation, phenotypic correlation, and descriptive statistical analysis of five milk production traits (milk yield, milk fat percentage, milk fat yield, milk protein percentage, and milk protein yield) of the dairy cows were analyzed using the SPSS and DMU software. Through quality control, 4173 cows and their genomes were used for genomic study. Then, SNPs were detected using DNA chips, and a copy number variation (CNV) analysis was carried out to locate the quantitative trait loci (QTL) of the milk production traits by Perl program software Penn CNV and hidden Markov model (HMM). The phenotypic means of the milk yield, milk fat percentage, milk fat mass, milk protein percentage, and milk protein mass at the first trimester were lower than those at the other trimesters by 8.821%, 1.031%, 0.930%, 0.003%, and 0.826%, respectively. The five milk production traits showed a significant phenotypic positive correlation (p < 0.01) and a high genetic positive correlation among the three parities. Based on the GGPBovine 100 K SNP data, QTL-detecting research on the fist-parity milk performance of dairy cows was carried out via the CNV. We identified 1731 CNVs and 236 CNVRs in the 29 autosomes of 984 Holstein dairy cows, and 19 CNVRs were significantly associated with the milk production traits (p < 0.05). These CNVRs were analyzed via a bioinformatics analysis; a total of 13 gene ontology (GO) terms and 20 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were significantly enriched (p < 0.05), and these terms and pathways are mainly related to lipid metabolism, amino acid metabolism, and cellular catabolic processes. This study provided a theoretical basis for the molecular-marker-assisted selection of dairy cows by developing descriptive statistics on the milk production traits of dairy cows and by locating the QTL and functional genes that affect the milk production traits of first-born dairy cows. The results describe the basic status of the milk production traits of the Chinese Holstein cows in Jiangsu and locate the QTL and functional genes that affect the milk production traits of the first-born cows, providing a theoretical basis for the molecular-marker-assisted selection of dairy cows.

Effect of feeding increasing levels of whole cottonseed on milk and milk components, milk fatty acid profile, and total-tract digestibility in lactating dairy cows

Dietary fat is fed to increase energy intake and provide fatty acids (FA) to support milk fat production. Oilseeds contain unsaturated FA that increase the risk for biohydrogenation-induced milk fat depression, but FA in whole cottonseed (WCS) are expected to be slowly released in the rumen and thus have a lower risk for biohydrogenation-induced milk fat depression. Our hypothesis was that increasing dietary WCS would increase milk fat yield by providing additional dietary FA without induction of milk fat depression. Four primiparous and 8 multiparous lactating Holstein cows, 136 ± 35 and 127 ± 4 DIM, respectively, were arranged in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were WCS provided at 0%, 3.4%, 6.8%, and 9.9% of dietary dry matter, and WCS was substituted for cottonseed hulls and soybean meal to maintain dietary fiber and protein. Treatment did not change milk yield. There was a treatment-by-parity interaction for milk fat percent and yield with a quadratic decreased in primiparous cows but no effect of WCS in multiparous cows. Cottonseed linearly increased milk fat trans-10 18:1 in primiparous cows but not in multiparous cows. Increasing WCS increased milk preformed (18C) FA yield and partially overcame the trans-10 18:1 inhibition of de novo FA synthesis in the primiparous cows. Apparent transfer of 18C FA from feed to milk decreased in all cows as WCS increased, but the magnitude of the change was greater in primiparous cows. Increasing WCS decreased total-tract apparent dry matter, organic matter, and neutral detergent fiber digestibility. There was no change in total FA digestibility. However, 18C FA digestibility tended to be decreased in both parities and 16C FA digestibility was quadratically increased in multiparous cows but not changed in primiparous cows. Total fecal flow of intact WCS increased as WCS level increased, but fecal flow of intact seeds as a percentage consumed was similar across treatments. Fecal flow of intact seeds was greater in multiparous cows (4.3% vs. 1.1% of consumed). Plasma concentrations of glucose, nonesterified FA, triglycerides, and insulin were not changed. However, plasma urea-N increased with increasing WCS. Plasma gossypol increased with WCS (0.08-1.15 µg/mL) but was well below expected toxic levels. In conclusion, WCS maintained milk and milk component yield when fed at up to 9.9% of the diet to multiparous cows without concerns of gossypol toxicity, but primiparous cows were more susceptible to biohydrogenation-induced milk fat depression in the current trial. This highlights the interactions of parity with diet composition when feeding rumen-available unsaturated fat to dairy cows.

Intravenous infusion of 5-hydroxytryptophan to mid-lactation Holstein cows transiently affects milk production and circulating amino acid concentrations

In dairy cows, the lactating mammary glands synthesize serotonin, which acts in an autocrine-paracrine manner in the glands and is secreted into the periphery. Serotonin signaling during lactation modulates nutrient metabolism in peripheral tissues such as adipose and liver. We hypothesized that the elevation of circulating serotonin during lactation would increase nutrient partitioning to the mammary glands, thereby promoting milk production. Our objective was to elevate circulating serotonin via intravenous infusion of the serotonin precursor 5-hydroxytryptophan (5-HTP) to determine its effects on mammary supply and extraction efficiency of AA, and milk components production. Twenty-two multiparous mid-lactation Holstein cows were intravenously infused with 5-HTP (1 mg/kg body weight) or saline, in a crossover design with two 21-d periods. Treatments were infused via jugular catheters for 1 h/d, on d 1 to 3, 8 to 10, and 15 to 17 of each period, to maintain consistent elevation of peripheral serotonin throughout the period. Milk and blood samples were collected in the last 96 h of each period. Whole-blood serotonin concentration was elevated above saline control for 96 h after the last 5-HTP infusion. Dry matter intake was decreased for cows receiving 5-HTP, and on average they lost body weight over the 21-d period, in contrast to saline cows who gained body weight. Milk production and milk protein yield were lower in cows receiving 5-HTP during the 3 infusion days, but both recovered to saline cow yields in the days after. Although milk fat yield exhibited a day-by-treatment interaction, no significant difference occurred on any given day. Milk urea nitrogen concentration was lower in 5-HTP cows on the days following the end of infusions, but not different from saline cows on infusion days. Meanwhile, plasma urea nitrogen was not affected by 5-HTP infusion. Circulating concentrations of AA were overall transiently decreased by 5-HTP, with concentrations mostly returning to baseline within 7 h after the end of 5-HTP infusion. Mammary extraction efficiency of AA was unaffected by 5-HTP infusion. Overall, both lactation performance and circulating AA were transiently reduced in cows infused with 5-HTP, despite sustained elevation of circulating serotonin concentration.

Heritability and Repeatability Estimates for Milk Production Traits Using Phenotypic, Pedigree-Based and Genomic Data of Serbian Holstein Cows

Summary This research aims to estimate heritability and repeatability based on the data on milk production traits (MY – milk yield; FY – milk fat yield; FC – milk fat content; PY – milk protein yield and PC – milk protein content) as well as pedigree and genomic information. A total of 6,041 animals were included in the research, while 2,565 of them had data for milk production traits. In order to form a genomic relationship matrix, 58K SNP data were used for a total of 1,491 cows. Several software tools were used in the preparation and analysis of data, which were provided by the Central Breeding Organization, Department of Animal Science, Faculty of Agriculture, University of Novi Sad. PreGSF90, in combination with RENUMF90, was used for quality control of genomic information. Genetic analysis was performed in WOMBAT software by the REML using standard repeatability univariate analysis (BLUPpe) and repeatability models for genomic prediction (GBLUPpe and ssGBLUPpe). In all three analyses, the highest heritability (0.410, 0.378 and 0.389, respectively) and repeatability (0.449, 0.429 and 0.440, respectively) were calculated for FC. Heritability estimates for all other traits were lower. Heritability ranged from 0.158 to 0.185 for MY, from 0.166 to 0.178 for FY, from 0.141 to 0.154 for PY and from 0.135 to 0.221 for PC. Heritability estimates indicate that it is possible to achieve genetic improvement but it is necessary to introduce the best model for prediction of breeding values of cow.

Grounding the economic selection index for evaluation and selection of dairy cattle

The aim of the research was to develop a selection index for the evaluation and selection of dairy cattle for increasing milk production and reproductive traits. Materials of the research were data on milk production and reproduction of cows of the Ukrainian Black-and-White dairy breed in commercial farm in Kharkiv region. Studies showed that there was a certain antagonism between milk productivity and reproduction of the Ukrainian Black-and-White dairy cow. The coefficients of phenotypic correlation between milk yield, fat and protein yield and the days open ranged from +0.284 to +0.293. Selection indexes were built, which included protein, fat yield, and days open. The developed selection indexes were characterized by a high relationship with the protein yield (α&lt;0.001), much lower – with the fat yield (α&lt;0.05), while the relationship of the selection indexes with the days open was almost absent. The calculated estimates of correlation and regression coefficients made possible to predict correlated responses of milk production and reproduction traits on selection index. The results showed that the developed selection indexes allow increase the milk production of cows and at the same time to prevent decrease in the level of reproduction.

Identification of genetic associations and functional SNPs of bovine KLF6 gene on milk production traits in Chinese holstein

BackgroundOur previous research identified the Kruppel like factor 6 (KLF6) gene as a prospective candidate for milk production traits in dairy cattle. The expression of KLF6 in the livers of Holstein cows during the peak of lactation was significantly higher than that during the dry and early lactation periods. Notably, it plays an essential role in activating peroxisome proliferator-activated receptor α (PPARα) signaling pathways. The primary aim of this study was to further substantiate whether the KLF6 gene has significant genetic effects on milk traits in dairy cattle.ResultsThrough direct sequencing of PCR products with pooled DNA, we totally identified 12 single nucleotide polymorphisms (SNPs) within the KLF6 gene. The set of SNPs encompasses 7 located in 5′ flanking region, 2 located in exon 2 and 3 located in 3′ untranslated region (UTR). Of these, the g.44601035G > A is a missense mutation that resulting in the replacement of arginine (CGG) with glutamine (CAG), consequently leading to alterations in the secondary structure of the KLF6 protein, as predicted by SOPMA. The remaining 7 regulatory SNPs significantly impacted the transcriptional activity of KLF6 following mutation (P < 0.005), manifesting as changes in transcription factor binding sites. Additionally, 4 SNPs located in both the UTR and exons were predicted to influence the secondary structure of KLF6 mRNA using the RNAfold web server. Furthermore, we performed the genotype-phenotype association analysis using SAS 9.2 which found all the 12 SNPs were significantly correlated to milk yield, fat yield, fat percentage, protein yield and protein percentage within both the first and second lactations (P < 0.0001 ~ 0.0441). Also, with Haploview 4.2 software, we found the 12 SNPs linked closely and formed a haplotype block, which was strongly associated with five milk traits (P < 0.0001 ~ 0.0203).ConclusionsIn summary, our study represented the KLF6 gene has significant impacts on milk yield and composition traits in dairy cattle. Among the identified SNPs, 7 were implicated in modulating milk traits by impacting transcriptional activity, 4 by altering mRNA secondary structure, and 1 by affecting the protein secondary structure of KLF6. These findings provided valuable molecular insights for genomic selection program of dairy cattle.

Milk production responses of dairy cows to fatty acid supplements with different ratios of palmitic and oleic acids in low- and high-fat basal diets

We evaluated the effects of fatty acid (FA) supplements with different ratios of palmitic acid (C16:0) and oleic acid (cis-9 C18:1) in low- and high-FA basal diets on production responses of lactating dairy cows. Thirty-six multiparous Holstein cows (50.2 ± 5.8 kg/d of milk; 160 ± 36 d in milk) were used in a split-plot Latin square design balanced for carryover effects. Cows were blocked by milk yield and allocated to a main plot receiving either a low-FA (LF; 1.93% FA content) basal diet (n = 18) containing cottonseed meal and cottonseed hulls or a high-FA (HF; 3.15% FA content) basal diet (n = 18) containing whole cottonseed. Within each plot, a 3 × 3 Latin square arrangement of treatments was used in 3 consecutive 21-d periods. Treatments were (1) control (CON; no FA supplementation), (2) FA supplement containing 80% C16:0 + 10% C18:1 (PA), and (3) FA supplement containing 60% C16:0 + 30% cis-9 C18:1 (PA+OA). The FA supplements were fed at 1.5% of dry matter and replaced soyhulls in CON. Preplanned contrasts were (1) overall effect of FA supplementation {CON vs. the average of the FA treatments [1/2 (PA + PA+OA)]}, and (2) the effect of the PA treatment versus the PA+OA treatment (PA vs. PA+OA). Treatment by basal diet interactions were observed for yields of milk and lactose, where FA treatments increased yields of milk and milk lactose in LF but not in HF. Basal diet had no effect on dry matter intake (DMI) or milk yield. Compared with LF, HF increased milk fat yield and 3.5% fat-corrected milk (FCM) and tended to increase milk fat content and energy-corrected milk (ECM) yield. The FA treatments decreased DMI but increased the yields of milk fat, 3.5% FCM, and ECM, compared with CON, due to increases in mixed and preformed milk FA yields. The PA+OA treatment decreased DMI and milk protein yield compared with PA. In conclusion, a high-fat basal diet increased milk fat production, and the addition of FA supplements to a low-fat basal diet increased milk lactose yield and tended to increase milk yield. Additionally, regardless of basal diet fat level, FA supplements increased production responses compared with the non-FA-supplemented control diet.