Prolactin gene polymorphism in Nili‐Ravi buffaloes in relation to Sahiwal and Achai Cattle

In this study, prolactin gene polymorphism was investigated in Nili‐ Ravi buffaloes, Sahiwal and Achai cattle breeds, 100 per group, using polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) technique. Only genotype GG was observed in the case of Nili‐Ravi buffaloes. In Sahiwal and Achai cattle, three genotypes were found, AA, AG and GG: the frequency of these genotypes were 72%, 18% and 10% in Sahiwal cattle and 44%, 34% and 22% in Achai cattle, respectively. The frequency of genotype AA was found to be higher in both cattle breeds. Results of chi‐square test at P < 0.05 revealed that animals of Achai cattle were in Hardy–Weinberg equilibrium, whereas Sahiwal cattle were found to be deviating.     

Analysis time and lactation stage influence on lactoperoxidase system components in dairy ewe milk

To study the effect of time elapsed from the moment of taking samples on lactoperoxidase system components, we analyzed the activity of the lactoperoxidase enzyme and the concentrations of thiocyanate and hydrogen peroxide in 46 individual samples of Manchega ewe milk. Samples were maintained at a temperature of 4 degrees C until analysis, which took place at 6, 12, 24, and 48 h after extraction. Decreases were observed in lactoperoxidase activity when the analyses were performed at 48 h and in the thiocyanate and hydrogen peroxide concentrations at 12 h compared with those carried out earlier. Consequently, when the components of the lactoperoxidase system or its antibacterial activity are studied, the time elapsed since the sampling commenced must be taken into account. Similarly, the time elapsed is important when carrying out bacterial counts or residue screening by microbiological methods, during which the lactoperoxidase system may interfere. To study the component changes in the lactoperoxidase system during lactation, samples obtained 15, 30, 45, 60, 75, 90, 105, 120, and 135 d postpartum from 48 Manchega ewes were used. Average lactoperoxidase activity, thiocyanate, and hydrogen peroxide concentrations were 3.46 U/ml, 6.89 mg/L, and 0.39 mg/L, respectively, with significant variations throughout lactation. The thiocyanate and hydrogen peroxide levels at different lactation stages seemed to be insufficient to activate the lactoperoxidase system. Nevertheless, this could be achieved by adding 5 mg/L of thiocyanate and 8 mg/L of hydrogen peroxide at any time during lactation.     

Diffusion of thiocyanate and hypothiocyanite in whey protein films incorporating the lactoperoxidase system

The diffusion of the thiocyanate (SCN⁻) and hypothiocyanite (OSCN⁻) components of a lactoperoxidase system (LPOS) in whey protein isolate (WPI) films was investigated. Diffusion coefficients for these molecules were measured for the LPOS-incorporated WPI films prepared with different WPI:glycerol ratios (1:1, 3:1, and 5:1). WPI film disks were coated on the surfaces of smoked salmon samples, and the samples were stored at 4, 10 and 22 °C. The diffusion coefficients were determined by fitting a mathematical model to the amounts of SCN⁻ and OSCN⁻ released from the disks during a period of time. The diffusion coefficients for SCN⁻ (D₁) and OSCN⁻ (D₂) in the films were 0.19–5.2 × 10⁻¹² m² s⁻¹ and 0.13–6.5 × 10⁻¹³ m² s⁻¹, respectively. The D₁ and D₂ decreased as the WPI:glycerol ratio increased and the storage temperature decreased. The E_a values for diffusion in 1:1, 3:1, and 5:1 WPI:glycerol films were 13.3, 29.5, and 35.6 kJmol⁻¹, respectively, for SCN⁻ and 15.8, 30.1, and 39.9 kJmol⁻¹, respectively, for OSCN⁻.     

Effect of activating lactoperoxidase system in cheese milk on the quality of Saint‐Paulin cheese

Saint‐Paulin cheese was made from cow’s milk refrigerated at 4 °C for 72 h and preserved by the lactoperoxidase (LP) system. The effect of the LP system on the microbiological, physicochemical and biochemical properties of cheese over a ripening period of 23 days was investigated, using a control (C0), refrigerated LP‐inactivated cow’s milk (C1) and refrigerated LP‐activated cow’s milk (LPA). The LPA treatment showed the least contamination in flora count, particularly salt‐tolerant bacteria at the end of the ripening period. LPA cheese had significantly lower coliform, yeasts and mould counts (P < 0.05) than the other cheeses; this demonstrated the bacteriostatic effect of the LP system. The proteolysis results showed the least value for LPA cheese as compared with the two other samples, as determined by using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of casein fractions extracted from the three samples. The findings indicated that the preservation of cow’s cheese milk by the LP system can be used to improve the microbiological quality, inhibit psychotropic germs, correct the losses of soluble nitrogen fractions in the whey and conserve the cheese yield affected by refrigeration.     

Effect of the lactoperoxidase system on the activity of mesophilic cheese starter cultures in goat milk

The effect of goats’ milk lactoperoxidase (LP) system on the activity of commercially available mesophilic cheese starter cultures was investigated. The growth and acid production of the starter cultures were measured at 2 h intervals for 8 h in goats’ milk kept at 30°C. Most of the starter cultures examined were found to be sensitive to the LP system, but varied in their susceptibility to inhibition. The activity of the mixed starter cultures CHN11, CHN22, CHN19, DCC240 and Flora Danica Normal was strongly inhibited by the LP system. However, the mixed starter culture LL 50C showed resistance to the LP system. The single strain culture Lactococcus lactis subsp. lactis NCDO 605 was inhibited by the LP system. However, the cultures Lactococcus lactis subsp. diacetylactis NCDO 176 and Leuconostoc mesenteroides subsp. cremoris ATCC 33313 were insensitive to the LP system. The results of this study indicate the need for routine screening of starter cultures for resistance to the LP system before using them for cheesemaking from goats’ milk preserved by the LP system.     

Κ‐CN gene polymorphism in Nili‐ravi buffalo,Achai and Sahiwal cattle of Pakistan

Kappa‐casein (κ‐CN) is the subtype of casein protein, an important constituent of bovine milk protein. The current study was undertaken to investigate the genetic polymorphism in κ‐CN gene of Nili‐ravi buffalo, Achai and Sahiwal cattle of Pakistan using polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) technique. The Nili‐ravi buffalo was found to be monomorphic (genotype BB only) for κ‐CN gene. Achai cattle were polymorphic for κ‐CN (having three genotypes AA, AB and BB) with a frequency of 0.70, 0.18 and 0.12, respectively, while in Sahiwal cattle, both the genotypes AA and AB were found with genotypic frequencies of 0.92 and 0.08, respectively. The presence of genotype BB in Achai cattle is surprising as it is absent in most of the cattle breeds worldwide.     

Lipolysis and the distribution of lipase activity in bovine milk in relation to stage of lactation and time of milking

The increase in levels of free fatty acids (FFA) in morning and afternoon milk after 48 h cold storage at 5 degrees C was determined at two stages of lactation in milk from 96 cows. Lipolysis was positively correlated to day of lactation (r = 0.6, P less than 0.001), while the correlations between lipolysis and milk yield and fat content respectively were due to these factors being related to day of lactation. In afternoon milk the level of FFA increased almost three times above that in morning milk. Lipolysis was closely related to the lipoprotein lipase (LPL) activity associated with the cream fraction (r = 0.8, P less than 0.001). Afternoon milk had higher LPL activity in the cream fraction than morning milk. Lipase activity in the cream increased with increasing stage of lactation. Cooling of milk increased LPL activity associated with the fat phase. This effect was greater in afternoon milk from late lactation than in morning milk from early lactation. When heparin was added to milk the LPL activity associated with the fat increased substantially; again, this effect was greater in afternoon milk from late lactation than in morning milk from early lactation. Lipolysis was higher in heparinized milk than in normal milk, and there was a close correlation between lipolysis and LPL activity associated with the fat (r = 0.82, P less than 0.001). Characteristics of the milk fat globule influencing the attraction of LPL were found to be fundamentally important to lipolysis.     

Energy and protein requirements of growing Nili‐Ravi buffalo heifers in tropical environment

Thirty Nili‐Ravi buffalo heifers (average initial weight 119 kg) were used to assess energy and protein requirements for maintenance and growth. The calves were randomly divided into six equal groups and were fed six diets consisting of three levels of energy (55%, 60% and 65% total digestible nutrient—TDN) in ration and two levels of protein (10% and 12% crude protein—CP) in ration in factorial arrangement ad libitum until they attained 400 kg body weight. Energy and protein requirements at different stages of growth were estimated by partitioning of the metabolizable energy (ME), CP and metabolizable protein (MP) intake for maintenance and body weight gain by regression analysis. All of the multiple regression equations derived for different body weight ranges were highly significant (P < 0.01) and had high R² values. The ME (kJ), CP (g) and MP (g) requirements for maintenance at different body weights were 443–542, 5.89–9.38 and 4.03–6.30 kg^?0.75 d^?1. The respective values for average daily gain in body weight (ADG) were 26–53, 0.24–0.48 and 0.18–0.31 g^?1 ADG d^?1. The predicted requirements matched well with their corresponding actual intake values across the data range. Regressed values were used to develop new feeding standards for buffalo heifers. Copyright © 2007 Society of Chemical Industry     

Inactivation of Gram-negative pathogens in refrigerated milk by reuterin in combination with nisin or the lactoperoxidase system

Inhibitory activity of reuterin (β-hydroxypropionaldehyde) combined with the antimicrobial peptide nisin or the lactoperoxidase system (LPOS) against food-borne Gram-negative pathogens in milk refrigerated at 4 and 8 °C was investigated. At 4 °C, reuterin (8 AU/ml) and LPOS were bactericidal against Salmonella enterica, Campylobacter jejuni, Aeromonas hydrophila and Yersinia enterocolitica, whereas the only effect recorded for nisin was a slight inhibition of Escherichia coli O157:H7. At 8 °C, reuterin was bactericidal against all the Gram-negative pathogens studied. Same results were attained with LPOS, except for its effect on Y. enterocolitica which was only bacteriostatic. The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin. A strong synergistic bactericidal activity of reuterin in combination with LPOS on E. coli O157:H7 and S. enterica was observed in milk at 4 °C, and against all the Gram-negative bacteria assayed in milk refrigerated at 8 °C. The application of both antimicrobials would be a useful means to inhibit pathogenic microorganisms, which may be present in milk due to postpasteurization contamination.     

Effects of an automatic milking system on milk yield and quality of Mediterranean buffaloes

A study was carried out to evaluate the effects of an automatic milking system (AMS) on milk yield and composition of buffalo (Mediterranean-type Bubalus bubalis) cows. Performed from January 2015 to December 2015 in an organic buffalo dairy farm equipped with both a traditional tandem milking parlor and an AMS, the study involved 90 primiparous buffaloes randomly allotted to a tandem or AMS group from 5 to 10 d of lactation onward. Number of milkings per day and daily milk yield of each cow were recorded, and individual milk sampling was carried out twice a month. Compared with the tandem, the AMS group showed significantly higher daily milk yield and persistence of lactation. Use of the AMS resulted in higher protein and casein contents, and lower somatic cell and total bacterial counts, whereas fat, freezing point, and pH were unaffected by the system. We conclude that, in terms of milk yield and quality, automatic milking may be a suitable alternative to conventional milking for buffaloes.     

Cheese‐making capacity of goat's milk during lactation: influence of stage and number of lactations

The effect of the stage and number of lactations on the technological properties and cheese‐making capacity was studied in Murciano‐Granadina goat's milk. Controls were done every month to evaluate the evolution of chemical composition and the values of the clotting properties which define the milk quality with regards to rennet curdling. The influence of the month of kidding was also evaluated. The average composition of the milk in the two kidding periods considered was as follows: fat 5.05% and 5.31%; protein 3.68% and 3.58%; casein 2.80% and 2.66%; lactose 4.71% and 4.68%, and dry matter 14.29% and 14.45%. No significant differences were found in the chemical composition due to the stage and lactation number; however, higher values of the protein fractions were determined in the first kidding period than in the second one. We determined that a higher casein concentration was associated with a lower milk clotting time and higher rate of firmness. We also found a highly significant (P < 0.001) correlation between titration acidity values and casein content (0.551). No significant differences, however, were found in cheese composition between kidding periods. © 1999 Society of Chemical Industry     

The effect of pre-milking teat-brushing on milk processing time in an automated milking system

Cow throughput in an automatic milking system (AMS) is limited by system parameters such as the time required for pre-milking udder preparation and cup attachment, physiological responses of the cow (such as milk let-down and milking-out rate), milking machine features and cow behaviour. A single-factor cross-over design was used to investigate the effect of pre-milking teat brushing on milk processing time in an AMS operating in an extensive grazing farming system. Teat brushing consisted of two roller brushes tracking up each teat three times (total brushing time of up to 45 s/cow). Cows were allocated to one of two treatment groups with either no brushing (NB) or brushing (B) for a 4-week period before being changed to the other treatment. Teat brushing resulted in shorter average cups-on-time (B = 506.1 s, NB = 541.0 s, P = 0.0001), longer average milk processing time (B = 10.30 min, NB = 9.76 min, P = 0.001) and no difference in daily milk yield (B = 14.67, NB = 14.71 kg/cow, P = 0.826). There was no difference between the two treatments in the success of cup attachment (B = 3.76%, NB = 5.10% unsuccessful milking attempts, P = 0.285). The estimated time cost of pre-milking teat brushing was 53 min for every 100 milkings, equivalent to an additional 5-6 milkings for every 100 milkings by an AMS. The importance of these potential time savings is discussed in relation to automatic milking in farming systems that aim for a lower per cow milking frequency and high ratio of cows to AMS.     

山羊乳过氧化物酶体系及其延长保鲜期的研究

分析了关中奶山羊羊奶中乳过氧化物酶活性和硫氰根质量浓度,对室温下应用化学法激活乳过氧化物酶体系保鲜羊奶进行研究.结果表明,羊奶中乳过氧化物酶活性为(1.88±1.17)U/mL,硫氰根质量浓度为(1.57±0.35)mg/L.均低于牛奶中的质量浓度.在25℃贮藏温度下,添加20 mg/L硫氰化钠添加20 mg/L比添加18.5 mg/L有明显优势.在添加20 mg/L硫氰化钠20 mg/L的基础上添加过碳酸钠比过氧化氢有更好的效果,差异显著(p<0.05).在添加20 mg/L硫氰化钠20 mg/L的基础上添加58.2 mg/L过碳酸钠58.2 mg/L可获得最佳保鲜效果,与空白对照相比差异显著(p<0.05),延长保鲜时间约6 h.     

Influence of breed, animal, and days of lactation on lactoperoxidase system components in goat milk

Lactoperoxidase and thiocyanate content in goat milk from two Spanish breeds throughout 5 mo of lactation has been investigated. Mean lactoperoxidase for milk from Verata and Murciano-Granadina goats was .95 and 2.15 units/ml, respectively. Very low concentrations, .03 units/ml for Verata and .20 units/ml for Murciano-Granadina, were found for the first 24 h after kidding. Highest concentrations were detected at the end of lactation (135 to 150 d) for Verata and in midlactation (60 to 75 d) for Murciano-Granadina goats. Mean thiocyanate content was 5.76 ppm for Verata goats, without a distinct maximum throughout lactation, and 3.20 ppm for Murciano-Granadina goats, with maximum levels at final lactation stages. Activation of the lactoperoxidase system might be a useful procedure in preserving raw goat milk quality by addition of low levels of thiocyanate and hydrogen peroxide.     

牦牛乳过氧化物酶体系及其酶热动力学研究

以麦洼牦牛乳为原料,分析了其乳过氧化物酶体系相关成分的浓度,并研究了不同温度下牦牛乳过氧化物酶(LPO)的热稳定性,利用一级反应动力学模型和阿仑尼乌斯方程,分析了牦牛乳中LPO在63～67℃热变性过程中的动力学参数。结果表明,牦牛乳LPO在63℃时具有较高的热稳定性。热动力学分析表明,牦牛乳LPO在63、65和67℃的D值分别为207.43、33.41、13.42min,在63～67℃范围内的Z值和表观活化能(Ea)分别为3.36℃和557.20kJ/mol。     

The effects of increased milking frequency during early lactation on milk yield and milk composition on commercial dairy farms

Increased milking frequency (IMF) during early lactation has the potential for carryover responses following the return to normal herd milking frequency. The objective was to determine the consistency of response of cows in commercial dairy farms to IMF during early lactation. Cows (n = 398) were assigned randomly at calving within each of the 4 participating farms to 1 of 2 treatments. The control group was milked twice-daily (2×) during the entire lactation. The IMF group was milked 4-times daily (4×) starting on d 1 to 7, depending on farm, until d 21 postcalving and 2× thereafter. Cows in the IMF group were milked at the beginning and again at the end of the normal milking routine. Milking intervals differed across the farms for the 4× cows with a minimum interval of 3.5, 4.0, 5.0, and 6 h for each of the 4 farms, respectively. The milk yield of cows subjected to IMF increased by 2.2 ± 0.4 kg/d during the first 7 mo of lactation. Interactions of treatment with lactation group (primiparous vs. multiparous) were not significant. Although percentages of fat and protein in milk were decreased by early lactation IMF (3.69% ± 0.03 fat and 3.05% ± 0.02 true protein for control vs. 3.57% ± 0.03 fat and 2.99% ± 0.02 true protein for IMF), overall yields of protein were increased by IMF (1.02 ± 0.01 vs. 0.98 ± 0.01 kg/d). Early lactation IMF did not affect udder health as assessed by somatic cell count linear score. Cows subjected to IMF were 1.4 times more likely classified as subclinically ketotic than the control cows. Early lactation IMF has the potential to increase milk yield on commercial dairy farms. Although the direction of response was the same on all farms, the magnitude of the response was different among farms and appears influenced by management practices specific to each farm, which included, but were not limited to, housing system, stocking density, nutrition, genetics, and other covariates differing among farms.     

Effects of once versus twice daily milking throughout lactation on milk yield and milk composition in dairy goats

The effects of once (1X) vs. twice (2X) daily milking throughout lactation on milk yield, milk composition, somatic cell count (SCC), and udder health were studied in 32 Murciano-Granadina dairy goats. Goats were assigned at wk 2 of lactation to two treatment groups; once daily milking at 0900 (1X, n = 17), or twice daily milking at 0900 and 1700 (2X, n = 15). Milk yield was recorded weekly until wk 28, and milk composition and SCC were evaluated for each individual udder half at each milking at wk 2 and 4 of lactation and then, monthly until the end of the experiment. Once daily milking resulted in an 18% reduction in the yield of 4% fat-corrected milk compared to twice daily milking (1.61 vs. 1.95 L/d, respectively). This reduction was more marked from wk 2 to 12 than in mid and late lactation. Response to milking frequency also varied according to parity number where goats of less than four parities suffered more milk yield losses during 1X than older goats. Milk of 1X goats contained higher percentages of total solids (13.6 vs. 12.9%), fat (5.10 vs. 4.62%) and casein (2.57 vs. 2.35%) than milk of 2X goats, but milk protein percentage did not differ between treatments (3.28 vs. 3.20%). Yields of total solids, fat, protein and casein tended to be higher for 2X than 1X. Milk SCC did not differ between treatments. We conclude that application of once daily milking in Murciano-Granadina dairy goats moderately reduced milk yield without negative effects on milk composition and udder health. Losses in milk yield would be reduced if 1X is practiced during mid- or late lactation and in older goats. An increase in labor productivity and a higher farmer's standard of living is also expected.     

Effect of different milking routines on milking-related release of the hormones oxytocin, prolactin and cortisol, and on milk yield and milking performance in Murrah buffaloes

Milking-related release of oxytocin, prolactin, and cortisol was studied following three premilking treatments. Six Murrah buffaloes were treated with direct application of milking cluster (O), a 1-min pre-stimulation (M), and combined feeding and pre-stimulation (MF). Machine milk yield, stripping yield and milk composition were recorded. Milk ejection occurred significantly earlier with MF than M and O (P<0.05; 2.50, 5.10 and 6.33 min, respectively). In all treatments, milk ejection occurred with small increases >3-5 ng/l in oxytocin concentration. Increase in oxytocin concentration over a threshold level and milk ejection occurred simultaneously and were closely correlated (r=0.83, P<0.05). There was a positive correlation between total time oxytocin concentration remained elevated over threshold levels and machine yield (r=0.86, P<0.05). For treatment O, milk ejection was inhibited during machine milking, while a marked increase in oxytocin occurred during hand stripping (6 and 16 ng/l, respectively). For treatment M, mean oxytocin concentrations remained unchanged during prestimulation but increased during subsequent machine milking and hand stripping (6.38, 18.06 and 12.36 ng/l, respectively). For treatment MF, although there was a 3.6-fold increase during pre-stimulation, oxytocin increased by 10-fold and 3-fold during machine milking and hand stripping, and was significant for machine milking (P<0.05, 17.32, 47.86, 18.13 ng/l, respectively). Milk-ejection-related cortisol release was visible only in treatment MF. For treatments O and M, prolactin concentration increased prior to the increase in oxytocin. The stripping yield was higher, and fat content in the stripping yield significantly lower, for treatment O indicating incomplete milking. Thus buffaloes are easily disturbed even by small changes in milking routines.     

Effect of lactation stage on the odd- and branched-chain milk fatty acids of dairy cattle under grazing and indoor conditions

The pattern of odd- and branched-chain fatty acids (OBCFA) in milk fat reflects rumen microbial activity and proportions of different rumen microbial groups. Therefore, these milk fatty acids (FA) are used to predict rumen proportions of volatile fatty acids, duodenal flow of microbial protein, and occurrence of rumen acidosis. However, current models do not correct for the potential effects of lactation stage on the level of OBCFA in milk fat. Hence, the objectives of this study were 1) to describe progressive changes related to lactation stage in concentrations of milk FA, with emphasis on the OBCFA, using the incomplete gamma function of Wood, and 2) to analyze whether lactation curves of milk FA on the one hand and milk production or milk fat content on the other hand coincide through evaluation of the correlation between the parameters of the Wood functions fitted to individual animal data. Data were collected from 2 trials in which milk FA during lactation were monitored. The first experiment was a stable trial with 2 groups of 10 cows receiving 2 dietary treatments from wk 1 to 40 of lactation. The second experiment was a grazing trial with 9 cows that were followed during the first 18 wk of lactation. Lactation curves of milk production, milk fat content, and individual milk FA were developed using the incomplete gamma function of Wood for each of the 3 dietary strategies separately. For almost all of the milk FA, lactation curve shapes were similar for all 3 dietary treatments. The OBCFA with chain lengths of 14 and 15 carbon atoms followed the lactation curves of the short- and medium-chain milk FA, which increased in early lactation. The OBCFA with chain length of 17 carbon atoms decreased during the early lactation period, following the pattern of milk long-chain fatty acids. The short- and medium-chain milk FA and OBCFA in the early lactation period seemed to be negatively correlated with the starting milk production and milk fat content, but correlations were modest. Information of milk FA lactation curves should be incorporated in predictive and classification models based on these milk FA, to improve their performance.