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At least 127 records · Page 7Linked to original sources
PubMed1993

Effects of oxytocin, machine stripping and milking rate on production loss of cows milked once a day.

The effect of treatments designed to improve the efficiency of milk removal and minimize loss of production in cows milked once a day (OAD) was assessed in short-term trials involving Friesian and Jersey cows. Trial 1 involved 80 cows and compared twice a day (TAD) milking with OAD milking with the administration of 20 i.u. of oxytocin (OX), OAD milking with udder massage before and during milking (OS) and no treatment during OAD milking (OC). The OX and OS groups had increased yields of milk and milk solids when treatments were applied, though yields were not restored to previous TAD levels. The percentage increase shown by OX cows was greater than that of OS cows for fat yield. The level of residual milk in the udder after milking was lower for the OX group than for the OAD and TAD controls. In Trial 2, 12 cows were subjected to fast or slow rates of milking OAD in each of two periods. Losses in milk, fat and protein yields averaged 9.1, 9.9 and 1.0% respectively. Increased rate of milking reduced milking time and time to let-down but did not affect response to OAD milking. The results showed that treatments that increased the evacuation of the udder during milking and decreased the level of residual milk reduced losses in production that occur on OAD milking. Increasing the rate of milking was ineffective in reducing losses on OAD milking.

Animals↗
PubMed2002

Milk quality on Danish farms with automatic milking systems.

The bulk-milk quality of 98 Danish farms with automatic milking systems was analyzed from 1 yr before introduction of automatic milking until 1 yr after. Bulk-milk total bacterial count, spores of anaerobes, somatic cell count (SCC), and freezing point increased when automatic milking was introduced and the frequency of milk-quality failures almost doubled. Milk-quality failures were most frequent in the first 3 mo after the start of automatic milking. The increase in spores of anaerobes indicated that the increase in total bacterial count originated partly from contamination of milk from the teat surface and partly from lack of cleaning of the milking equipment or cooling of the milk. The increase in bulk-milk SCC indicated that milk from clinically infected cows and cows with high cell counts was not diverted to the same degree, milking automatically rather than milking conventionally. A self-monitoring program including survey of the bulk-milk quality was established to help farmers in the transition period going from conventional to automatic milking. The program was introduced on 84 farms. Farms on the self-monitoring program reduced bulk-milk cell count. Application of the program did not reduce the frequency of high total bacterial counts and freezing points of the bulk milk to the level of conventional milking. However, the program reduced the overall frequency of milk-quality failures.

Animals↗
PubMed1987

Methods to assess the propensity of milk fat globules toward lipolysis and the ability of skim milk to inhibit lipolysis.

Methods to quantitate factors in milk relevant to cold-induced lipolysis are described. Skim milk was incubated with milk fat globules isolated from a pool of normal milk and a fixed amount of purified lipoprotein lipase. The release of fatty acids in 24 h at 4 degrees C was determined. Most skim milk samples inhibited lipolysis, but the effect varied greatly. Skim milk from milk prone to spontaneous lipolysis was less inhibitory than skim milk from normal milk. In general, both the casein and the serum fractions of skim milk inhibited lipolysis. However, variation was greater in the effects of individual samples of milk serum. In a few extreme cases, with samples from milk with spontaneous lipolysis, the serum fraction actually stimulated lipolysis. Globules were isolated and then incubated with skim milk from normal milk and a fixed amount of purified lipoprotein lipase. This gave a measure of accessibility to lipolysis of milk fat globules in normal skim milk. There was a considerable variation in propensity toward lipolysis between milk fat globules from individual milk samples. Milk showing different levels of lipolysis obtained from five cows revealed that skim milk inhibition of lipolysis and the propensity of milk fat globules toward lipolysis were characteristic for each cow.

Animals↗
PubMed2001

Effect of milking frequency on oxytocin release and milk production in dairy ewes.

The experiment was conducted to investigate the effectiveness of milking stimulus on oxytocin release and to compare the effect of milking frequency on plasma levels of oxytocin and milk parameters. Twelve Lacaune ewes were subjected to six treatments (T1, T2, T3, T4, T5 and T7 daily milkings) during 6 days. At each milking, blood was sampled and plasma oxytocin levels were determined by enzyme immunoassay. Baseline levels of oxytocin were similar for all milking frequencies. The start of milking was followed by a significant increase in oxytocin levels for all milking frequencies. One daily milking induced significantly higher oxytocin levels than 2, 3, 4, 5 and 7 daily milkings. Milk yield was significantly increased between 4 (1787.0+/-141.5ml) and 7 (1780.0+/-53.6ml) daily milkings compared to 1 (1104.0+/-81.2ml) daily milking. Total concentration of milk protein did not change, but the total milk fat yield for 5 (73.0+/-2.0g/l) and 7 (72.8+/-1.4g/l) daily milkings were significantly higher than for 1 (58.1+/-4.3g/l) daily milking. This study confirmed milk yield gains caused by frequent milk ejection and also showed that oxytocin release was not a limiting factor for milk yield gain when daily milking frequency was increased.

Journal Article↗
PubMed1995

Interruption of machine milking in dairy cows: effects on intramammary pressure and milking characteristics.

Experiments were designed to test the hypothesis that milk ejection rate decreases during milking, thereby causing insufficient refill of the cistern and decreasing milk flow rate towards the end of milking. In a first series of experiments machine milking of the left front quarters of 11 cows was interrupted for 2 min after removal of 25, 50 or 75% of expected total milk yield, while milking was continued in the other three quarters. Milk flow was recorded during machine-on times. Intramammary pressure (IMP) was recorded during premilking teat stimulation and during interruption of milking. IMP during interruption of milking decreased with decreasing amounts of milk remaining in the udder. The IMP did not change during these interruptions when they occurred after 25 and 50% of expected total milk yield was removed. Thus, the ejection rate could keep up with the milk flow or removal rate. However, IMP increased during interruption of milking following removal of 75% of total yield, although significantly so only in cows with a high milk flow rate. Obviously, more milk was removed than was transported to the cisternal cavity. It is likely that a reduced ejection rate caused the decreased milk flow rate. In a second series of experiments the pulsation ratio of the milking machine was changed from the usual 70:30 to 50:50 with the aim of reducing the milk flow rate and thus adapting to the ejection rate at the end of milking. The changed pulsation ratio caused a reduced peak flow rate and a prolonged high milk flow period, whereas the main flow rate did not change significantly.

Animals↗
PubMed2003

Milk and milk components reduce the motility of Ostertagia circumcincta larvae in vitro.

AIM: To examine the effects in vitro of bovine milk and milk products and soymilk on the motility of sheathed and exsheathed L3 Ostertagia circumcincta (also known as Teladorsagia circumcincta) as a measure of larval viability and infectivity. METHODS: L3 were exsheathed in 0.2% sodium hypochlorite, resuspended in Hank's Balanced Salt Solution (HBSS) pH 7.4 and incubated with test solutions at 37 degrees C for up to 48 h. The motility of 50 larvae from each incubate was assessed at selected times using a McMaster slide. Larvae were considered immotile only if straight and not moving. Fresh bovine milk, homogenised milk (3.3% fat), low-fat milk (0.2% fat) and lamb milk replacer were diluted with HBSS pH 7.4 to concentrations from 1.6-100%, and incubated with exsheathed L3 for 1, 24 or 48 h. Bovine whey protein was tested in concentrations of 5-15% at pH 2.5-6.5, casein at 5 or 7.5%, and skim milk powder from 5-15% at pH 5.5 or 6.5, all for 2, 4 or 24 h. Soymilk was tested in concentrations of 1.6-100% for 1, 2, 24 or 48 h. HBSS was used as the control solution. Sheathed L3 were incubated in HBSS pH 7.4, 50% homogenised milk in HBSS, or 50% soymilk in HBSS. Each solution was incubated for 1,2, 24 or 48 h. RESULTS: The motility of exsheathed L3 was reduced by fresh bovine milk, homogenised milk, low-fat milk, lamb milk replacer, whey, casein and skim milk solutions, but not by soymilk. The mean percentage (and SE) immotile at 48 h were: fresh milk 38% (SE 20); homogenised milk 65% (SE 7); low-fat milk 57% (SE 5); lamb milk replacer 43% (SE 7); and soymilk 7% (SE 0.5). Larval immotility increased in whey protein solutions from 5-15%, from pH 2.5-6.5 and from 2 to 24 h (all p<0.001); in skim milk from 5-15% (p<0.001), and was greater at pH 6.5 than at pH 5.5 (p<0.001); in casein from 5-7.5% (p<0.001), but was no different at pH 5.5 and 6.5. The motility of sheathed L3 was reduced at 24 h (p=0.009) and 48 h (p<0.001) by 50% homogenised milk, but not by 50% soymilk or HBSS. CONCLUSIONS: Bovine milk proteins, or components associated with the proteins, reduced the motility of both sheathed and exsheathed L3 O. circumcincta. Soymilk had no effect on nematode motility. Lower larval motility may reduce worm establishment and be a contributing factor to the smaller burdens of gastrointestinal nematodes in milk-fed animals compared with animals after weaning.

Journal Article↗
PubMed1994

Simulating individual cow milk yield for milking parlor simulation models.

A method of simulating individual cow milk yield per milking as a function of herd milk yield and month was formulated for milking parlor simulation models. Milk yield per milking was modeled for each month in three herd milk yield categories: 8165, 8845, and 9525 kg/yr of milk per cow. Actual individual cow DHIA test day milk weight data for three Florida dairy herds in each herd milk yield category and month were adjusted to the mean of their respective actual milk shipped per cow on test day then pooled and converted to a basis of three times per day milk yield per milking. After minor truncation, Weibull probability distributions fitted to these data sets adequately modeled milk yield per milking per cow. Analysis of simulation results for milk yield per milking per cow indicated no significant differences between actual and simulated means for any herd milk yield category or month. Simulations of monthly and yearly total herd milk yield for each herd indicated that fitted Weibull distributions also adequately modeled monthly and yearly herd milk yield characteristics and reflected seasonal herd milk yield patterns typical of Florida.

Animals↗
PubMed2006

Risk evaluation for staphylococcal food poisoning in processed milk produced with skim milk powder.

The growth of S. aureus and the production of staphylococcal enterotoxin A (SEA) in skim milk concentrates stored at inappropriate temperatures in a recovery milk tank (tank for excess concentrated skim milk) used in the manufacture of skimmed milk powder were investigated. Also, it was estimated if a possible outbreak of food poisoning would occur if the contaminated skimmed milk powder was used in the manufacture of processed milk. Skim milk concentrates with milk solid content of 15, 25, and 35% were inoculated with S. aureus at 1-2 log CFU/ml and incubated at 15, 25, or 35 degrees C for 0 to 24 h with or without shaking. Bacterial growth and the level of SEA production were measured. At 35 degrees C with shaking, there was a significant difference (p<0.05) in one way layout analysis of variance, and it was demonstrated that the growth of S. aureus and SEA production could be milk solid content-dependent. Shaking accelerated the growth of S. aureus and SEA production at 35 degrees C. Generally, skim milk powder is produced by mixing a set percentage of skim milk concentrates (recovery milk) from the recovery milk tank into raw milk. If recovery milk contaminated with S. aureus at levels of 1-2 log CFU/ml is kept at 15 to 35 degrees C due to a power failure, it was estimated that processed milk consumption of 670-1200 ml, 420-1500 ml and 18-83 ml would trigger the onset of food poisoning symptoms when skim milk concentrates (recovery milk) are stored at 25 degrees C for 24 h, 35 degrees C for 10 h, and 35 degrees C for 24 h, respectively, during the production of the skim milk powder. Based on these consumption levels, it was concluded that, if recovery milk cannot be refrigerated and is stored at room temperature (25 to 35 degrees C), it must be used within 8 h and preferably within 6 h.

Animals↗
PubMed1994

Milk accumulation and distribution in the bovine udder during the interval between milkings.

The proportions of milk stored within the gland cistern (cisternal milk) and within secretory alveolar tissue (alveolar milk) were determined at various intervals after milking in peak lactation cows and late lactation cows. The rate of milk secretion remained constant up to 12 h in both groups. Cisternal milk remained low (600 g or less) until after 4 h in both groups, then increased gradually to values at 12 h of 5.08 (peak lactation) and 2.60 kg (late lactation). Alveolar milk exceeded cisternal milk in both groups and at all time points up to 12 h, and was greatest in the peak lactation cows. A further measurement was made at 20 h in the late lactation group. Milk secretion rate remained constant between 12 and 20 h and most of this additional milk accumulated in the cistern. Alveolar fraction, defined as alveolar milk as a proportion of total milk, ranged from 0.43 to 0.94 at 8 h. There was a highly significant correlation between 8 h and 20 h alveolar milk fraction results, but not between 1 h and 8 h values, nor between alveolar milk at 0 h (effectively residual milk) and alveolar fraction at any time point. The milk volume results were used to construct a mathematical model describing milk flow between cisternal and alveolar compartments, and hence the pattern of milk accumulation. The results are discussed in relation to current hypotheses regarding local autocrine control of milk secretion by a feedback inhibitor in milk.

Animals↗
PubMed1983

The effects of milking thrice instead of twice daily on milk secretion in the goat.

Milk yields of goats milked twice daily at 16/8 h intervals or 12/12 h intervals were equal. In goats normally milked twice daily at 16/8 h intervals, one mammary gland was milked thrice daily for one week while the other continued to be milked twice daily. This was done at 3, 7, 16, 24 and 33 weeks of lactation. Feeding level was maintained during these experiments. At every stage of lactation, thrice-daily milking increased milk yield (by about 8%). Stage of lactation had no effect on the size of the response. Yields of each gland increased by as much in an experiment involving thrice-daily milking both glands. Milk yield increased as soon as thrice-daily milking was started, and decreased towards normal values as soon as twice-daily milking was resumed. Milk composition during thrice-daily milking was unaffected with respect to concentrations of Na+, K+, Cl-, lactose, protein, fat and citrate. There was no change in milk yield of the gland which continued to be milked twice daily. The stimulatory effect was entirely local to the gland receiving the extra milking. Milk secretion rate during the 16 h period which included the extra milking was significantly higher during thrice-daily than during twice-daily milking; secretion rate during the rest of the day was unaffected. There were significant diurnal variations in secretion rate during thrice-daily milking such that the secretion rate during the 23.00-07.00 h period was highest and the secretion rate during the 07.00-15.00 h period was the lowest.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗