Erratum to "Organic zinc supplementation in early-lactation dairy cows and its effects on zinc content and distribution in milk and cheese" (JDS Commun. 2:110-113).

[This corrects the article DOI: 10.3168/jdsc.2020-0070.].

Organic zinc supplementation in early-lactation dairy cows and its effects on zinc content and distribution in milk and cheese.

This study investigated the effects of organic zinc (Zn) supplementation in early-lactation dairy cows on Zn content and distribution in raw milk and mozzarella cheese. Thirty-four multiparous dairy cows in early lactation were randomly assigned to 2 groups: basal diet (control; CON) and basal diet supplemented with a Zn AA complex (CZ). After feeding the diets for 8 wk, raw milk was collected for manufacturing mozzarella cheese. Total Zn content and Zn distribution in raw milk and cheese were determined by atomic absorption spectrophotometry. Results showed that milk fat content was significantly increased in the CZ group compared with the CON group. No significant differences in fat, protein, and moisture contents of cheese were observed between the 2 groups. Zinc contents in milk (4.25 vs. 3.85 mg/L) and cheese (38.65 vs. 27.20 mg/kg) were significantly higher in the CZ group than in the CON group. Little Zn was lost in stretch water (<0.04 mg/L) and brine (<0.01 mg/L) during the cheese-making process. Most of the Zn was detected in casein (87.3% vs. 88.4%) of the raw milk, and then in the whey (10.6% vs. 9.88%) and fat (2.07% vs. 1.77%). Organic Zn supplementation in early-lactation cows increased Zn content in raw milk and mozzarella cheese, and Zn remained stable during cheese making.

Short communication: Influence of intramuscular injection of vitamin B12 in early-lactation dairy cows on Mozzarella cheese quality and vitamin B12 stability.

The current study explored the effect of intramuscular injection of vitamin B12 (VB12) in early-lactation dairy cows on subsequent low-moisture part-skim Mozzarella cheese quality and VB12 levels during cheese processing and storage. Twenty-four peripartum dairy cows were blocked based on parity and milk yield and randomly assigned into 2 treatments: basal diet (CON) and basal diet with an intramuscular injection of 10 mg of VB12 per cow per week (VB12). Raw milk was collected to determine VB12 content and then used to make low-moisture part-skim Mozzarella cheese 8 wk after injection. The VB12 content of raw milk and cheese was determined using ultra-performance liquid chromatography coupled with tandem mass spectrometry. We found that VB12 content was significantly increased in milk (15.43 vs. 3.30 ng/mL) and fresh cheese (3.72 ng/g vs. undetectable) from the VB12 group compared with the CON group. However, approximately 70% of VB12 was lost in the whey during cheese making, and no VB12 was detectable in either cheese treatment after 8 wk of storage. Furthermore, no significant differences were observed in fat and protein contents in the cheese between the 2 groups. For cheese color, the b* value increased and the a* value decreased slightly in fresh VB12 cheese. Functional properties of stretchability, flowability, and meltability of VB12 cheese were initially comparable to that of CON cheese, but higher flowability and meltability was observed in VB12 cheese after 8 wk of storage. In summary, intramuscular injection of VB12 in early-lactation dairy cows increases the content of VB12 in milk and fresh cheese with no adverse effect on cheese quality, but substantial VB12 is lost during cheesemaking and declines rapidly during storage.

Short communication: Effects of dietary N-carbamoylglutamate supplementation on the milk amino acid profile and mozzarella cheese quality in mid-lactating dairy cows.

N-Carbamoylglutamate (NCG) is an enhancer of Arg, which is a functional AA and could prevent cardiovascular disease and improve immunity. The present study was conducted to investigate the effects of supplementing NCG in diets of lactating cattle on the NCG concentration and AA composition of raw milk and on mozzarella cheese quality. Thirty multiparous cows with a mean body weight of 669 kg (standard deviation = 71) and days in milk of 176 (standard deviation = 55) were blocked based on parity and milk production and randomly assigned to 1 of 2 treatments: basal diet (CON) and basal diet supplemented with 40 g of NCG per day per cow (NCG). After 8 wk of treatment, raw milk samples were collected from the 2 groups for AA analysis and mozzarella cheese-making. Furthermore, the NCG concentration and distribution in milk and mozzarella cheese were detected. The AA concentration in milk was greater and the NCG concentration in raw milk was approximately 6 times greater in the NCG group than in the CON group. No NCG was detected in cheese from the CON group, and very little NCG (<1.0 µg/kg) of cheese was detected in the NCG group. Most of the dietary NCG was transferred into whey, stretch water, and brine during cheese production. No significant difference was found between the 2 groups on cheese texture and color except that hardness was lower in the NCG group. Overall, the results indicated that dietary supplementation of NCG could improve the NCG and AA concentrations in raw milk without affecting the quality of cheeses such as mozzarella.

Comparing the effect of homogenization and heat processing on the properties and in vitro digestion of milk from organic and conventional dairy herds.

We compared the effects of homogenization and heat processing on the chemical and in vitro digestion traits of milk from organic and conventional herds. Raw milk from organic (>50% of dry matter intake from pasture) and conventional (no access to pasture) farms were adjusted to commercial whole and nonfat milk fat standards, and processed with or without homogenization, and with high-temperature-short-time or UHT pasteurization. The milk then underwent in vitro gastrointestinal digestion. Comparison of milk from organic and conventional herds showed that the milks responded to processing in similar ways. General composition was the same among the whole milk samples and among the nonfat milk samples. Protein profiles were similar, with intact caseins and whey proteins predominant and only minor amounts of peptides. Whole milk samples from grazing cows contained higher levels of α-linolenic (C18:3), vaccenic (C18:1 trans), and conjugated linoleic acids, and lower levels of palmitic (C16:0) and stearic (C18:0) acids than samples from nongrazing cows. Processing had no effect on conjugated linoleic acid and linolenic acid levels in milk, although homogenization resulted in higher levels of C8 to C14 saturated fatty acids. Of the 9 volatile compounds evaluated, milk from grazing cows contained lower levels of 2-butanone than milk from nongrazing cows, and milk from both farms showed spikes for heptanal in UHT samples and spikes for butanoic, octanoic, nonanoic, and N-decanoic acids in homogenized samples. At the start of in vitro digestion, nonfat raw and pasteurized milk samples formed the largest acid clots, and organic milk clots were larger than conventional milk clots; UHT whole milk formed the smallest clots. Milk digests from grazing cows had lower levels of free fatty acids than digests from nongrazing cows. In vitro proteolysis was similar in milk from both farms and resulted in 85 to 95% digestibility. Overall, milk from organic/grass-fed and conventional herds responded in similar ways to typical homogenization and heat processing used in United States dairy plants and showed only minor differences in chemical traits and in vitro digestion. Findings from this research enhance our knowledge of the effect of processing on the quality traits and digestibility of milk from organic/pasture-fed and confined conventional herds and will help health-conscious consumers make informed decisions about dairy selections.

Effect of feed selenium supplementation on milk selenium distribution and mozzarella quality.

In the present study, the effect of feed Se supplementation on the Se content of raw milk and mozzarella cheese as well as the effect on cheese quality and functionality were determined. The Se milk was produced by supplying dairy cow feed with Se yeast (0.3mg of Se/kg of dry matter), resulting in a Se concentration in milk of 35.81µg/L. The fat, casein, and whey protein of Se milk were separated by ultracentrifugation, and the Se content was determined by atomic absorption spectroscopy. The Se distribution in different milk fractions of fat, casein, and whey protein were 9.82, 45.56, and 44.62%, respectively. The Se mozzarella cheese was made by Se milk, and the composition and texture of Se cheese did not significantly differ from that of the control. However, the functional properties (meltability, flowability, and stretchability) of the Se cheese were better after 8 wk of storage. Moreover, the pH and water activity were lower in Se cheese, which decreased the total plate count. The Se content in mozzarella cheese was 4 fold higher than that in milk, and Se was found in the whey, hot water, and brine collected during cheesemaking. Organic and inorganic Se was found in the Se cheese after 8 wk of storage, and most Se peptides detected after storage were Se-Met and Se-Cys. The results of this study show that feed Se supplementation can improve the Se content of milk and cheese without affecting mozzarella cheese quality.

Association between genetic polymorphisms of PTGS2 and glioma in a Chinese population.

Several previous studies indicated that genetic polymorphisms in inflammatory factor genes were associated with glioma risk. However, the relationship between the prostaglandin-endoperoxide synthase 2 (PTGS2) genetic polymorphism and glioma remains unclear in the Chinese population. We selected 199 histologically confirmed adult glioma patients and 199 cancer-free controls for the present study and analyzed the distribution of the PTGS2 genotypes and haplotypes. We found that the CC+CT genotype of rs5275 was common in the control group but not in the glioma group (P = 0.033). In addition, we found that the frequency of the C allele was higher in the control group than in the glioma group (P = 0.014). For rs6681231, although we found no significant difference between the 2 groups in genotype distribution, we found that the frequency of the C allele was lower in glioma patients than in control subjects (P = 0.044). We found no significant difference between these 2 groups in the rs689466 genotype and allele distributions. Haplotype analysis suggested that the frequency of the C-A-C haplotype was significantly lower in glioma patients than in control subjects [P = 0.028, odds ratio (OR) = 0.628, 95% confidence interval (CI) = 0.413-0.955]. However, the frequency of the T-A-G haplotype was higher in glioma patients than in control subjects (P = 0.036, OR = 1.418, 95%CI = 1.022-1.967). Therefore, polymorphisms in the PTGS2 gene may be associated with glioma susceptibility in the Chinese population.

Effects of the processing methods of corn grain and soybean meal on milk protein expression profiles in dairy cows.

A proteomic approach was used to investigate the effects of the processing method of corn grain and soybean meal on the milk protein expression profile in lactating dairy cows. A total of 12 multiparous Holstein dairy cows were used in a 4×4 Latin square design with a 2×2 factorial arrangement. The primary factors examined were corn (finely ground (FGC) v. steam-flaked (SFC)) and soybean meal (solvent-extracted (SSBM) v. heat-treated (HSBM)), which were used to formulate four diets with the same basal ingredient: 27% FGC and 9% SSBM; 27% SFC and 9% SSBM; 27% FGC and 9% HSBM; and 27% SFC and 9% HSBM. Each period lasted for 21 days. Milk samples were collected on days 18, 19 and 20 of each period. Changes in the milk proteins were assessed by two-dimensional (2D) electrophoresis and ImageMaster 2D Platinum 6.0 software. A total of 13 spots displayed variations in protein spot abundance according to the statistical analysis. These spots were identified by a matrix-assisted laser desorption/ionization-time of flight/time of flight MS. According to the gels, the relative abundance of α(s2)-casein (CN) fragments was higher in the cows fed the SFC-HSBM than that for SFC-SSBM, whereas ß-CN, α-lactalbumin and zinc-alpha-2-glycoprotein fragments were down-regulated in HSBM-fed cows. The relative decrease of ß-CN expression was validated by western blot and agreed with the MS data. These results suggested that the method used to process soybean meal modified the synthesis and secretion of milk proteins in lactating dairy cows' mammary glands.

Changes in the resistance of Plasmodium falciparum to chloroquine in Hainan, China.

In 1979, in view of the widespread resistance of Plasmodium falciparum to chloroquine in the island of Hainan, China, it use as an antimalarial was suspended throughout the island. A longitudinal survey of the chloroquine-sensitivity of P. falciparum was carried out over the period 1981-91 to investigate whether its resistance had changed from the 1979 level. In-vitro assays were carried out every 2-3 years, while in-vivo tests were performed annually over the period 1981-83 and also in 1991. Resistance to chloroquine declined progressively after its use had stopped. The in-vitro tests indicated that the rate of chloroquine-resistant P. falciparum was 97.9% in 1981, but dropped to 60.9% in 1991 (P < 0.001). The mean concentration of chloroquine for complete inhibition of schizont formation was 10.4 pmol/microliters in 1981, but decreased to 3.0 pmol/microliters in 1991 (P < 0.001). The proportion of samples taken from malaria cases that required high concentrations ( > 6.4 pmol/microliters) of chloroquine for complete inhibition of schizont formation was 83.3% in 1981, but only 17.4% in 1991 (P < 0.001); at low concentrations ( > 1.6 pmol/microliters), the corresponding proportions increased from 4.2% in 1981 to 60.8% in 1991 (P < 0.001). In the 4-week in-vivo test, the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 40% in 1991 (P < 0.001). RII + RIII cases represented 59.4% of the total resistant cases in 1981, but decreased to 37.5% in 1991 (0.02 > P > 0.01).

[Alteration in resistance of Plasmodium falciparum to chloroquine after cessation of chloroquine medication for twelve years].

In view of the fact the resistance of Plasmodium falciparum to chloroquine occurred extensively in Hainan, a decision was made in 1979 that the use of chloroquine should be quit in the whole province. A longitudinal survey on chloroquine-sensitivity of P. falciparum was carried out during 1981-1991 to observe the variation in resistance of the parasite after the cessation of the chloroquine medication for every 2-3 years. A tendency of progressive decline of resistance was revealed. By using in vitro test, the rate of chloroquine-resistant P. falciparum dropped from 97.9% in 1981 to 60.9% in 1991 (P < 0.001). The mean dosage of chloroquine for complete inhibition of schizont formation declined from 10.46 pmol/microliters in 1981 to 3.02 pmol/microliters in 1991 (P < 0.001). The percentage of population requiring larger dosage (6.4 pmol/microliters to completely inhibit schizont formation declined from 83.3% in 1981 to 17.4% in 1991 (P < 0.001); whereas those requiring small dosage (1.6 pmol/microliters), increased from 4.2% in 1981 to 60.8% in 1991 (P < 0.001). In in vivo test, the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 40% in 1991 (P < 0.001). The proportion of RII plus RIII cases of the total resistant cases dropped from 59.4% in 1981 to 37.5% in 1991 (0.02 > P > 0.01).

[A handy medium for in vitro assessment of sensitivity of Plasmodium falciparum to chloroquine and mefloquine in the field].

The use of liquid RPMI 1640 medium (added NaHCO3 and serum) in sealed ampoule for in vitro assessment of sensitivity of Plasmodium falciparum to chloroquine and meflopuine in the field was very successful. On chloroquine plates with WHO supplied medium, 9 of 13 isolates were interpretable (successful rate 69.2%), the maturation rate from ring-forms to schizonts was 53.3%, the average number of nuclei per schizont 5.1. With lyophilized medium the successful rate was 100%, the maturation rate 65.9%, the average number of nuclei per schizont 7.4, while with medium in sealed ampoule, the corresponding figures were 92.3%, 65.1% and 7.3 respectively. On mefloquine plates with WHO supplied medium, 7 of 11 isolates were interpretable (63.6%). In control wells, 52.3% of schizonts matured, the number of nuclei per schizont was 5.1. With lyophilized medium the successful rate was 100%, the maturation rate 61.9%, the number of nuclei was 8.1, while those with liquid medium in sealed ampoule were 100%, 59.8% and 7.5 respectively. The results showed that the liquid medium in sealed ampoules stored within 56 days at 4 degrees C could still support the growth of Plasmodium falciparum, its supporting effect being better than that of WHO standard medium, but similar to lyophilized medium. The liquid medium in sealed ampoule had the advantages of easy carrying time-saving and more applicability under field conditions.