Milk Performance Of Dairy Cows Research Articles

The impact of citrus pulp inclusion on milk performance of dairy cows: A meta-analysis

Considering sustainability and circular economy, citrus pulp could become a common dairy feedstuff. Yet, there is no clear indication of the amount of citrus pulp that can be fed without compromising milk performance or that could deliver benefits. In our meta-analysis, we investigated the impact of varying citrus pulp inclusion levels, i.e., no (0 %), low (>0–10 %), medium (>10–20 %), and high (>20 %), on milk performance variables. Replacing cereal grains with citrus pulp increased pectins and sugars while decreasing starch. At the low inclusion level, citrus pulp increased milk yield without affecting feed intake. At higher inclusion levels, citrus pulp reduced feed intake and milk yield but with higher fat contents, the milk energy content was similar to no inclusion. Concluding, citrus pulp is a good energy source with lipogenic properties in dairy cows. We encourage research to fill in the existing gap of knowledge at the rumen and systemic levels.

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.

Feeding lower-protein diets based on red clover and grass or alfalfa and corn silage does not affect milk production but improves nitrogen use efficiency in dairy cows

Reducing the dietary crude protein (CP) concentration can decrease the financial cost and lower the environmental impact of milk production. Two studies were conducted to examine the effects of reducing the dietary CP concentration on animal performance, nutrient digestibility, milk fatty acid (FA) profile, and nitrogen use efficiency (NUE; milk N/N intake) in dairy cows fed legume silage-based diets. Thirty-six multiparous Holstein-Friesian dairy cows that were 76 ± 14 (mean ± SD) days in milk and 698 ± 54 kg body weight were used in a 3 × 3 Latin square design in each of 2 studies, with 3 periods of 28 d. In study 1, cows were fed diets based on a 50:50 ratio of red clover to grass silage [dry matter (DM) basis] containing 1 of 3 dietary CP concentrations: high (H) = 175 g of CP/kg of DM; medium (M) = 165 g of CP/kg of DM; or low (L) = 150 g of CP/kg of DM. In study 2, cows were fed 175 g of CP/kg of DM with a 50:50 ratio of alfalfa to corn silage (H50) or 1 of 2 diets containing 150 g of CP/kg of DM with either a 50:50 (L50) or a 60:40 (L60) ratio of alfalfa to corn silage. Cows in both studies were fed a total mixed ration with a forage-to-concentrate ratio of 52:48 (DM basis). All diets were formulated to meet the MP requirements, except L (95% of MP requirements). In study 1, cows fed L ate 1.6 kg of DM/d less than those fed H or M, but milk yield was similar across treatments. Mean milk protein, fat, and lactose concentrations were not affected by diet. However, the apparent total-tract nutrient digestibility was decreased in cows fed L. The NUE was 5.7 percentage units higher in cows fed L than H. Feeding L also decreased milk and plasma urea concentrations by 4.4 mg/dL and 0.78 mmol/L, respectively. We found no effect of dietary treatment on the milk saturated or monounsaturated FA proportion, but the proportion of polyunsaturated FA was increased, and milk odd- and branched-chain FA decreased in cows fed L compared with H. In study 2, DM intake was 2 kg/d lower in cows receiving L50 than H50. Increasing the alfalfa content and feeding a low-CP diet (L60) did not alter DMI but decreased milk yield and milk protein concentration by 2 kg/d and 0.6 g/kg, respectively, compared with H50. Likewise, milk protein and lactose yield were decreased by 0.08 kg/d in cows receiving L60 versus H50. Diet had no effect on apparent nutrient digestibility. Feeding the low-CP diets compared with H50 increased the apparent NUE by approximately 5 percentage units and decreased milk and plasma urea concentrations by 7.2 mg/dL and 1.43 mmol/L, respectively. Dietary treatment did not alter milk FA profile except cis-9,trans-11 conjugated linoleic acid, which was higher in milk from cows receiving L60 compared with H50. We concluded that reducing CP concentration to around 150 g/kg of DM in red clover and grass or alfalfa and corn silage-based diets increases the apparent NUE and has little effect on nutrient digestibility or milk performance in dairy cows.

Effect of corn shredlage on feed intake, rumen fermentation, and lactation performance of dairy cows fed a low-fibre diet

Corn shredlage is a whole-plant corn silage with a greater proportion of long particles and intensively processed stalks (by shredding and peeling) and kernels (by thorough crushing). Corn shredlage may improve rumen function and milk performance of dairy cows, especially in low-fibre diets. Paradoxically, little is known about the specific effects of corn shredlage on rumen fermentation. This study aimed to understand how the dietary replacement of corn silage with corn shredlage changes feed intake, rumen fermentation, rumination time, and milk performance of dairy cows fed a low-fibre diet. Thirty-four lactating cows were allocated to two dietary treatments in a crossover design with two 30-day periods. The dietary treatment was a total mixed ration with either 1) 25% conventionally processed corn silage (CON; 14-mm theoretical length of cut, TLOC) or 2) 25% corn shredlage (SHR; 26-mm TLOC). Cows on the SHR diet had increased DMI and body weight. Although milk yield was unaffected by diet, cows on the SHR diet tended to have increased yields of 4% FCM, ECM, and milk fat. The yields of milk protein and lactose were not affected by diet. Similarly, the proportion of milk components remained unaffected. The feed efficiency (milk/DMI) was higher in cows fed the CON diet, whereas it remained unaffected when expressed as ECM/DMI. Neither rumination nor rumen fermentation parameters were affected by the diet. Overall, the positive effects of corn shredlage on milk performance were relatively small and a result of increased DMI rather than improved rumen fermentation or rumination. HIGHLIGHTS Corn shredlage increased DMI Corn shredlage tended to increase yields of 4% FCM, ECM, and milk fat Corn shredlage did not affect rumination and rumen fermentation

RNA-Seq Reveals the Role of miR-29c in Regulating Inflammation and Oxidative Stress of Bovine Mammary Epithelial Cells.

Healthy mammary gland is essential for milk performance in dairy cows. MicroRNAs (miRNAs) are the key molecules to regulate the steady state of mammary gland in dairy cows. This study investigated the potential role of miR-29c in bovine mammary epithelial cells (bMECs). RNA sequencing (RNA-seq) was used to measure the transcriptome profile of bovine mammary epithelial cells line (MAC-T) transfected with miR-29c inhibitor or negative control (NC) inhibitor, and then differentially expressed genes (DEGs) were screened. The results showed that a total of 42 up-regulated and 27 down-regulated genes were found in the miR-29c inhibitor group compared with the NC inhibitor group. The functional enrichment of the above DEGs indicates that miR-29c is a potential regulator of oxidative stress and inflammatory response in bMECs through multiple genes, such as forkhead box O1 (FOXO1), tumor necrosis factor-alpha (TNF-α), and major histocompatibility complex, class II, DQ alpha 5 (BoLA-DQA5) in the various biological process and signaling pathways of stress-activated mitogen-activated protein kinase (MAPK) cascade, Epstein-Barr virus infection, inflammatory bowel disease, etc. The results imply that miR-29c plays an important role in a steady state of bMECs or cow mammary gland and may be a potential therapeutic target for mastitis in dairy cows.

Response of Milk Performance, Rumen and Hindgut Microbiome to Dietary Supplementation with Aspergillus oryzae Fermentation Extracts in Dairy Cows.

Fungal additives had beneficial effects on milk performance in dairy cows. Previous studies investigating the effects of fungal additives mainly focused on the rumen, such influences on the hindgut remain limited. This study aimed to investigate the effects of Aspergillus oryzae fermentation extracts (AOE) on the milk performance and microbiome in the rumen and hindgut using 16S rRNA gene sequencing. Twenty lactating multiparous Holstein cows were randomly assigned to control and treatment (5g AOE per cow per day). The results showed that AOE increased the milk yield, milk protein and lactose concentration, but did not affect the milk fat concentration. Feeding AOE did not affect the ruminal VFA pattern, pH, NH3-N, and microbial cell protein production, but decreased lipopolysaccharide concentration and tended to decrease lactate concentration. The addition of AOE increased the fecal pH and the proportions of propionate, isovalerate and valerate, and decreased the acetate to propionate ratio. PCoA analysis showed that AOE did not affect the overall ruminal bacterial population composition. Only three genera changed slightly in relative abundance. In the feces, PCoA analysis showed that AOE changed the bacterial population composition. Feeding AOE increased the relative abundances of Ruminococcaceae UCG-010 and unclassified Clostridiales vadinBB60 group, and decreased Christensenellaceae R-7 group, unclassified Muribaculaceae, Prevotellaceae UCG-001 and Romboutsia. Spearman correlation showed unclassified Clostridiales vadinBB60 group was positively correlated with propionate proportion. Overall, we present that AOE not only functioned in rumen, but also in hindgut. The hindgut microbiome changes might play an important role in the milk performance improvement of dairy cows.

Association of Feed Efficiency, Feeding Rate, and Behaviour with the Milk Performance of Dairy Cows

Identification of the associations of cow feed efficiency with feeding behaviour and milk production is important for supporting recommendations of strategies that optimise milk yield. The objective of this study was to identify associations between measures of feed efficiency, feed intake, feeding rate, rumination time, feeding time, and milk production using data collected from 26 dairy cows during a 3 month period in 2018. Cows averaged (mean ± standard deviation) 2.2 ± 1.7 lactations, 128 ± 40 days in milk, 27.5 ± 5.5 kg/day milk, 1.95 ± 0.69 kg feed/1 kg milk—the measure used to express feed conversion ratio (FCR), 575 ± 72 min/day rumination time, and 264 ± 67 min/day feeding time during the observation period. The coefficient of variation for rumination time (min/d) was 12.5%. A mixed linear model was selected for analyses. The most feed inefficient cows with the highest FCR (≥2.6 kg feed/1 kg milk) showed the lowest milk yield (24.8 kg/day), highest feed intake (78.8 kg), highest feeding rate (0.26 kg/min) and BCS (3.35 point). However, the relative milk yield (milk yield per 100 kg of body weight) was the highest (4.01 kg/day) in the most efficient group with the lowest FCR (≤1.4 kg feed/1 kg milk). Our study showed that the most efficient cows with the lowest FCR (≤1.4 kg feed/1 kg milk) had the highest rumination time (597 min/day; p &lt; 0.05), feeding time (298 min/day; p &lt; 0.05), rumination/activity ratio (4.39; p &lt; 0.05) and rumination/feeding ratio (2.04; p &lt; 0.05). Less active cows (activity time 164 min/day; p &lt; 0.05) were the most efficient cows with the lowest FCR (≤1.4 kg feed/1 kg milk). The behavioural differences observed in this study provide new insight into the association of feed behaviour and feed efficiency with milk performance. Incorporating feeding behaviour into the dry matter intake model can improve its accuracy in the future and benefit breeding programmes.

Milk performance of dairy cows supplemented with a combination of slow-release nitrogen and exogenous fibrolytic enzyme

The purpose of this on-farm trial was to evaluate the impact of supplementing slow-release nitrogen (SRN; min. 40% N) and exogenous fibrolytic enzyme (EFE; cellulase, xylanase, glucanase, mannanase and xylanase-potentiating factor) products on milk yield and composition in dairy cows. Twelve early-to-midlactating crossbred cows were divided into 2 groups with comparable milk production. Animals were fed on a total mixed ration comprising of green maize, wheat straw and concentrate mixture. Group T1 was supplemented with urea at 80 g/animal/d, whereas that of T2 received a novel combination of cellulo-polymer-coated SRN at 80 g and EFE at 4 g/animal/d for a period of 20 days. Results showed no difference in milk yield (13.8 vs. 15.1 kg/d; P=0.559) between the groups; however, milk fat (3.49 vs. 3.87%) and solid not fat (7.92 vs. 8.35%) levels were higher (P<0.05) in group T2 than T1. Furthermore, on applying 2-axis milk payment system, group T2 demonstrated a return on investment of 8.3:1. It was, therefore, concluded that supplementing a combination of SRN and EFE carries practical worth to enhance milk composition, thereby boosting economic gain in dairy farming under Indian context.

Diet supplementation with thyme oil and its main component thymol failed to favorably alter rumen fermentation, improve nutrient utilization, or enhance milk production in dairy cows

Phenolic compounds and essential oils with high content of phenolic compounds have been reported to exert antimicrobial activities in vitro. The objective of this study was to determine the effects of dairy cow diet supplementation with thyme oil and its main component thymol on intake and total-tract apparent digestibility of nutrients, rumen fermentation characteristics, ruminal protozoa, nitrogen excretion, and milk production. For this aim, we used 8 multiparous, ruminally cannulated Holstein cows in a replicated 4 × 4 Latin square design (28 d periods), balanced for residual effects. Cows were fed 1 of the 4 following experimental treatments: total mixed ration (TMR) with no additive (control); TMR + monensin [24 mg/kg of dry matter (DM)]; TMR + thyme oil (50 mg/kg of DM); and TMR + thymol (50 mg/kg of DM). Compared with the control diet, feeding thyme oil or thymol had no effect on DM intake, nutrient total-tract apparent digestibility, total N excretion, ruminal pH, ammonia concentration, total volatile fatty acid (VFA) concentration, or acetate:propionate ratio. Ruminal protozoa density was not modified by thyme oil, but decreased with thymol supplementation. Supplementation with thyme oil or thymol did not affect milk production, milk composition, or efficiency of milk production. Neither thyme oil nor thymol affected efficiency of dietary N use for milk N secretion (N intake/milk N). Supplementation with monensin tended to decrease DM intake (-1.2 kg/d) and milk fat yield. Total-tract apparent digestibility of nutrients did not differ between cows fed monensin and cows fed the control diet. Total VFA concentration was not changed by monensin supplementation compared with control, but adding monensin shifted the VFA profile toward more propionate and less acetate, resulting in a decrease of acetate:propionate ratio. Protozoa density and ammonia concentration were lower in the ruminal content of cows fed monensin compared with that of cows fed the control diet. Total N excretion was not affected by monensin supplementation. Likewise, efficiency of use of dietary N for milk N secretion was unchanged in cows fed monensin. The results of this study contrasted with the claimed in vitro antimicrobial activity of thyme oil and thymol: we observed no positive effects on rumen metabolism (i.e., N and VFA) or milk performance in dairy cows. Under the conditions of this study, including thyme oil or thymol at 50 mg/kg of DM had no benefits for rumen fermentation, nutrient utilization and milk performance in dairy cows.

Short communication: Relationship of blood DNA methylation rate and milk performance in dairy cows

The objective of this study was to investigate the global methylation rate in blood DNA and its relationship with lactation performance. A total of 196 mid-lactation dairy cows were fed the same diet under the same management. Milk yield was recorded and blood samples were collected from the jugular vein before morning feeding. The blood global DNA methylation rates were quantified using a methylation quantification kit. Overall, the average blood global DNA methylation rate of all cows was 12.4%. When DNA methylation rates were compared between cows with high (n = 40; 37.0 to 42.0 kg/d) and low (n = 33; 24.0 to 30.0 kg/d) milk yield, DNA methylation rates in the lower-yield cows (14.1 ± 0.7%) were significantly higher than those in the higher-yield animals (11.6 ± 0.7%). Our results indicated an association of milk and protein yields with global DNA methylation rates in lactating dairy cows. However, further research is needed to determine whether this association reflects the true influence of epigenetic mechanisms on yield or whether other factors, such as different proportions of blood cell types in high- and low-yielding cows, affect apparent global DNA methylation levels.

An energy-protein feed additive containing different sources of fat improves feed intake and milk performance of dairy cows in mid-lactation.

This research paper addresses the hypothesis that calcium salts combined with whole linseed and heat-treated rapeseed cake in one feed additive may efficiently stimulate the productivity of dairy cows and have a positive effect on the functional (health-promoting) properties of milk fat. The article proposes the composition of such an additive (EFA) and evaluates its nutritional effect in the diet of mid-lactation dairy cows. Forty multiparous Polish Holstein-Friesian (PHF) dairy cows were allocated to one of four treatments (10 cows/treatment) and fed a TMR diet without EFA or with EFA in the amount of 1, 2 or 3 kg/d per head for a 63-d-period. Individual intake of dry matter (DMI) and nutrients was determined, as was milk yield and composition, including fatty acid profile, fat soluble vitamins, cholesterol and phospholipids (PLs). Irrespective of the treatment group, cows fed diets with EFA had higher (P &lt; 0.05) DMI, milk yield and milk vitamin D3 and K2 concentration but lower (P &lt; 0.01) milk protein, fat and cholesterol contents. The additive did not affect the milk concentrations of β-carotene or vitamin A or E. The PLs content was correlated with fat concentration in the milk and decreased as the level of EFA in the diet increased. An increase in phosphatidylcholine in total PLs was accompanied by a reduction in the proportion of sphingomyelin (P &lt; 0.05). The use of EFA increased the proportion of polyunsaturated fatty acids (PUFA) in the total fatty acids in the milk. The addition of EFA in the amount of 3 kg increased the proportion of PUFA by 77% (P &lt; 0.05). In conclusion, the use of an energy-protein feed additive (EFA) increases feed intake and milk yield in cows and alters milk fat composition, improving its functional properties. Higher milk production compensates for the decrease in solids concentration in the milk, which has no effect on their daily yield.

Analysis of hepatic transcript profile and plasma lipid profile in early lactating dairy cows fed grape seed and grape marc meal extract

BackgroundIt was recently reported that dairy cows fed a polyphenol-rich grape seed and grape marc meal extract (GSGME) during the transition period had an increased milk yield, but the underlying reasons remained unclear. As polyphenols exert a broad spectrum of metabolic effects, we hypothesized that feeding of GSGME influences metabolic pathways in the liver which could account for the positive effects of GSGME in dairy cows. In order to identify these pathways, we performed genome-wide transcript profiling in the liver and lipid profiling in plasma of dairy cows fed GSGME during the transition period at 1 week postpartum.ResultsTranscriptomic analysis of the liver revealed 207 differentially expressed transcripts, from which 156 were up- and 51 were down-regulated, between cows fed GSGME and control cows. Gene set enrichment analysis of the 155 up-regulated mRNAs showed that the most enriched gene ontology (GO) biological process terms were dealing with cell cycle regulation and the most enriched Kyoto Encyclopedia of Genes and Genomes pathways were p53 signaling and cell cycle. Functional analysis of the 43 down-regulated mRNAs revealed that a great part of these genes are involved in endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) and inflammatory processes. Accordingly, protein folding, response to unfolded protein, unfolded protein binding, chemokine activity and heat shock protein binding were identified as one of the most enriched GO biological process and molecular function terms assigned to the down-regulated genes. In line with the transcriptomics data the plasma concentrations of the acute phase proteins serum amyloid A (SAA) and haptoglobin were reduced in cows fed GSGME compared to control cows. Lipidomic analysis of plasma revealed no differences in the concentrations of individual species of major and minor lipid classes between cows fed GSGME and control cows.ConclusionsAnalysis of hepatic transcript profile in cows fed GSGME during the transition period at 1 week postpartum indicates that polyphenol-rich feed components are able to inhibit ER stress-induced UPR and inflammatory processes, both of which are considered to contribute to liver-associated diseases and to impair milk performance in dairy cows, in the liver of dairy cows during early lactation.

Effect of feeding ensiled mixture of pomegranate pulp and drier feeds on digestibility and milk performance in dairy cows.

Based on a previous ensiling study in glass silos of various pomegranate pulp (PP) mixtures, fresh pomegranate pulp (PP) was mixed with drier feeds including soy hulls and corn silage (40:35:25 on DM basis) and ensiled in 32 pressed bales (700 kg each) wrapped with stretch polyethylene film. This ensiled pomegranate pulp mixture (PPM) was included in lactating cow total mixed ration (TMR) at a level of 20% of DM (PPM-TMR). Performance and digestion experiment was conducted with two groups of 21 milking cows each, fed individually one of the two TMR: 1. Control TMR without ensiled PPM; 2. Experimental TMR which contained 20% ensiled PPM, including 8% PP as corn grain replacer. Voluntary DM intake of cows fed the control TMR was 5.04% higher than that of the PPM cows. In vivo digestibility of DM, OM, NDF, CP and fat were significantly higher in the control cows compared with the PPM group, but methane production in the rumen fluid was 25% lower in the PPM cows. A slightly higher milk yield (by 2.2%) observed in the control cows; however, milk fat content was 5.9% higher in the PPM cows. This was reflected in similar yield of energy corrected milk (ECM) and 3.97% increase in production efficiency (ECM/DM intake) of the PPM cows compared with the control ones. Welfare of the cows, as assessed by length of daily recumbence time, was in the normal range for both groups. Body weight gain was also similar in both groups. Data suggest that the level of 8% PP in the PPM-TMR used in this study was probably too high for lactating cows and should be lowered to 4% in order to achieve better performance.

Effect of cysteamine hydrochloride supplementation on the milk performance of dairy cow

Cysteamine (CS) can increase serum growth hormone concentrations and the growth performance of broiler, sheep, and pigs. However, information of CS supplementation on the milk performance of dairy cows is limited. An experiment was conducted to investigate the effect of dietary cysteamine hydrochloride (CSH) supplementation on lactation performance of dairy cows. Forty-eight multiparous mid-lactation Holsteins were fed a control diet or supplemented with 15, 30, or 45g/d CSH preparation (cysteamine HCl 20%) for 63d, including 7d for adaptation. The base diet was formulated to meet the nutrient requirements of lactating dairy cows according to the Chinese feeding standard (China Standard NY/T 34,Feeding standard of dairy cattle 2004 Issued by Ministry of Agriculture of People's Republic of ChinaBeijing) and the DMI, milk yield, milk composition, and plasma parameters were measured. Milk yield was 7.1% and 6.3% higher for the two higher supplementation amounts (SEM=0.50, P<0.05), and milk protein content was 7.7%, 8.7%, and 8.1% higher for the three supplemented groups (SEM=0.077, P<0.05), respectively, than the control. Plasma urea N were lower for the 30 and 45g/d CSH groups than for the control. Level of plasma somatostation was reduced and plasma growth hormone was enhanced in CSH groups compared with that of control (P<0.01). Supplementation of CSH preparation at 30g/d increased milk production of dairy cows while 15g/d has no positive effect on milk yield or milk efficiency.

Correlation between the Insertion/Deletion Mutations of Prion Protein Gene and BSE Susceptibility and Milk Performance in Dairy Cows

Abstract Objective To investigate the 23 bp and 12 bp insertion/deletion (indel) mutations within the bovine prion protein (PRNP) gene in Chinese dairy cows, and to detect the associations of two indel mutations with BSE susceptibility and milk performance. Methods Based on bovine PRNP gene sequence, two pairs of primers for testing the 23 bp and 12 bp indel mutations were designed. The PCR amplification and agarose electrophoresis were carried out to distinguish the different genotypes within the mutations. Moreover, based on previous data from other cattle breeds and present genotypic and allelic frequencies of two indels mutations in this study, the corrections between the two indel mutations and BSE susceptibility were tested, as well as the relationships between the mutations and milk performance traits were analyzed in this study based on the statistical analyses. Results In the analyzed Chinese Holstein population, the frequencies of two “del” alleles in 23 bp and 12 bp indel muations were more frequent. The frequency of haplotype of 23del-12del was higher than those of 23del- 12ins and 23ins-12del. From the estimated r2 and D’ values, two indel polymorphisms were linked strongly in the Holstein population (D’ = 57.5%, r2 = 0.257). Compared with the BSE-affected cattle populations from the reported data, the significant differences of genotypic and allelic frequencies were found among present Holstein and some BSE-affected populations (P &lt; 0.05 or P &lt; 0.01). Similarly, there were significant frequency distribution differences of genotypes and alleles among Chinese Holstein and several previous reported healthy dairy cattle (P &lt; 0.05 or P &lt; 0.01). Moreover, association of genotype and combined genotypes of two indel polymorphisms with milk performance and resistant mastitis traits were analyzed in Holstein population, but no significant differences were found (P &gt; 0.05). Conclusions These observations revealed that the influence of two indel mutations within the bovine PRNP gene on BSE depended on the breed and they did not affect the milk production traits, which layed the foundation for future selection of resistant animals, and for improving health conditions for dairy breeding against BSE in China.

Milk performance of dairy cows supplemented with rape seed oil, peanut oil, and sunflower seed oil

The objective of the study was to investigate the effects of supplementing different plant oils to the basal diet on milk yield and milk composition in mid-lactating dairy cows. Forty Chinese Holstein dairy cows averaging 120 days in milk (DIM) at the start of the experiment (body weight = 580 &amp;plusmn; 18.2 kg; milk yield = 33.0 &amp;plusmn; 2.00 kg/day) were used in a completely randomized block design. The animals were assigned to four dietary treatments according to DIM and milk yield, and supplemented with no oil (control), 2% rapeseed oil (RSO), 2% peanut oil (PNO) and 2% sunflower seed oil (SFO). Milk yield and milk composition (fat, protein, and lactose) were measured. Dry matter intake was similar in all treatments. The supplementation of plant oil increased milk yield, with the highest milk yield in RSO group. Percentages of milk fat, lactose, solids-not-fat and SCC were not affected by treatments except for an increase in milk protein content in oil supplemented groups. The fatty acid (FA) profile of milk was altered by fat supplementation. Feeding plant oils reduced the proportion of both short-chain (C4:0 to C12:0) and medium-chain (C14:0 to C16:1) fatty acids, and increased the proportion of long-chain (&amp;ge; C18:0) fatty acids in milk fat. The inclusion of vegetable oils increased the concentration of cis-9, trans-11 CLA. The cis-9, trans-11 CLA content in milk fat was higher from RSO to PNO and SFO was higher than the control. The TVA concentration was higher in the SFO diet, followed by PNO, RSO, and control diets. The results of this study indicated that linoleic acid was more effective in enhancing contents of TVA and CLA in milk fat than oleic acid. No significant effects of week and treatment by week interaction were found out in this study. Overall, feeding plant oils increased monounsaturated and polyunsaturated fatty acids and decreased saturated fatty acids in milk fat. In conclusion, dietary supplementation of RSO increases milk yield the most, while SFO enhances the cis-9, trans-11 CLA content in milk fat more effectively.

Prediction of Second Parity Milk Performance of Dairy Cows from First Parity Information Using Artificial Neural Network and Multiple Linear Regression Methods

Prediction of Second Parity Milk Performance of Dairy Cows from First Parity Information Using Artificial Neural Network and Multiple Linear Regression Methods

Effects of energy balance and metabolizable protein level on tissue mobilization and milk performance of dairy cows in early lactation

The objective of this study was to investigate the effect of dietary energy and metabolizable protein supply on feed intake, milk production, blood metabolites and tissue mobilization in dairy cows during the first 14 weeks of lactation. In the experiment, 36 Norwegian Dairy Cattle were used. Three dietary treatments were evaluated, (1) protein and energy supply according to standard recommendations (SS) for amino acids absorbed in the small intestine (AAT) and net energy lactation (NE L), (2) low protein and low energy (LL; 50% of the concentrate energy fed to SS) and (3) high protein (135% of that fed to LL) and low energy (HL). Energy corrected milk (ECM) was not significantly different between SS and HL but both were higher than LL ( P<0.05), 4.6 and 2.8 kg higher, respectively. Increased AAT supply at low energy intake increased ( P<0.05) ECM, protein yield and stimulated increased mobilization of fat. The latter was verified by higher levels ( P<0.05) of non-esterified fatty acids and acetoacetate in blood and acetone in milk. However, increased fat mobilization showed no effect on incidence of ketosis. It is concluded that the AAT supply in early lactation is an important factor in regulating milk yield and milk protein production.

Milk production in early lactation dairy cows given grass silagead libitum: Influence of concentrate energy source, crude protein content and level of concentrate allowance

ABSTRACTThere is increasing interest in how the raw material make-up of concentrates can influence the milk performance of dairy cows. Thus, over two consecutive winters, 54 dairy cows were used to investigate the effects on dry matter (DM) intake, milk yield and its composition of feeding concentrates of diverse energy source (LNDF — 131 g neutral-detergent fibre per kg DM, 492 g starch plus sugars per kg DM; HNDF — 244 g neutral-detergent fibre per kg DM, 293 g starch plus sugar per kg DM) at two formulated crude protein (CP) levels (157v.187 g/kg DM) and three levels of concentrate allowance (9, 11, 13 kg DM). The concentrates were formulated to be of equivalent metabolizable energy concentration (MJ/kg DM) and were offered with silagead libitumfor a 10-week period (weeks 4 to 13 of lactation).Silage intakes were variable but not significantly influenced by concentrate energy source or formulated CP level, except in the 1st year where animals consuming the high CP concentrate ate more silage. Silage DM intake decreased as concentrate allowance was increased with the substitution rate (kg silage DM per kg concentrate DM) increasing as concentrate allowance was increased.Increasing the concentrate allowance effected the expected increases in milk yield. Concentrate energy source did not influence milk yield but the higher CP levels effected a 2-kg increase in milk yield. Feeding of LNDF concentrates depressed milk fat concentration and its yield, the depression being accentuated with each increase in concentrate allowance. The depression in milk fat concentration was negatively correlated with the forage: concentrate ratio of the diet consumed. Furthermore, dietary NDF proportion was shown to account for greater than half of the variation in milk fat concentration. In contrast to the observations made for milk fat, feeding the LNDF concentrates effected an increase in milk protein concentration but only at the lower CP level of the concentrate.

The influence of concentrate energy source on dairy cow performance

There is currently increasing interest in the diversity of materials which may be used as energy sources for dairy cow diets. Feeding of concentrates with a high “digestible fibre” content may be of benefit to the lactating dairy cow. In comparison with a concentrate based on a highly fermentable energy source such as cereal starch a concentrate high in digestible fibre content may undergo a slower fermentation within the rumen such that the resultant fermentation pattern may be altered. Diets and feeding regime's that promote low rumen volatile fatty acid ratios of acetic plus butyric:propionic have been associated with the production of milk of low fat content. Feeding of a high “digestible fibre” concentrate may therefore help prevent this problem. The purpose of the trial reported here was to compare the effects of concentrate energy source on the milk performance of dairy cows in early lactation.