Day-to-day variation in milk yield, fat content and protein content

Syrstad, Ola

doi:10.1016/0301-6226(77)90031-8

Cited by 20 publications

(15 citation statements)

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“…Very few interfering factors had a significant effect on the residuals. The RMSE of the models were similar to the inherent variability of milk fat measurements: they were lower than the day-to-day variations in milk fat measured in vivo (Syrstad, 1977;Forsback et al, 2010) and were similar to the residual variations (r.s.d.) calculated from the publications included in the database (the r.s.d.…”

Section: Discussionsupporting

confidence: 56%

Response of milk fat concentration and yield to nutrient supply in dairy cows

Maxin

Rulquin

Glasser

2011

Animal

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Dietary changes alter dairy cow milk fat concentration (MFC) and yield (MFY) through modifications in the supply of nutrients, which act as precursors or inhibitors of mammary fat synthesis. The current models used to formulate dairy cow diets cannot predict changes in milk fat. The knowledge of the effects of the nutrients on milk fat would help to progress toward this prediction. To this end, we quantified and compared the milk fat responses to variations in the supply of seven nutrients derived from digestion: volatile fatty acids, glucose, proteins, long-chain fatty acids (LCFA) and t10,c12-conjugated linoleic acid (CLA). A database was compiled from studies involving digestive infusions of these nutrients in dairy cows. It included 147 comparisons between a nutrient infusion and a control treatment. The nutrient infusions were limited to the range of physiological variations to mimic nutrient changes after dietary modifications. We established models for the response of MFC, MFY and milk fatty acid (FA) composition to the supply of each nutrient. MFC and MFY responses to the nutrients were significant and linear, except for the MFC response to glucose that was curvilinear. The nutrients differed in their effects on MFC and MFY: acetate, butyrate and LCFA increased MFC and MFY, whereas propionate, glucose and t10,c12-CLA decreased them. Protein infusions increased MFY and decreased MFC because of an increase in milk yield. The effects of numerous interfering factors related to animals, diets or experimental conditions were tested on the residuals of the response models. The responses of milk FA percentages are also provided. When adjusted to the in vivo variations in the nutrients observed after dietary changes, the effects of the different nutrients were moderate. Finally, this study showed that several of these nutrients could contribute to the changes in milk fat production and composition observed after dietary changes. This is a first step toward predicting milk fat response to changes in nutrient supply.Keywords: milk fat, dairy cow, meta-analysis, nutrients ImplicationsFluctuations in the milk fat market are driving demands from farmers for ways to control milk fat production and composition in dairy cows. The current models used to estimate dairy cow requirements and formulate diets cannot predict changes in milk fat. These models are based on energy and protein intake and do not consider the pattern of individual nutrients derived from digestion. Using published infusion studies, this meta-analysis quantifies and compares the effects on milk fat secretion of several nutrients derived from digestion. It is a first step toward a model to estimate variations in milk fat based on variations in nutrient supply.

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Section: Discussionsupporting

confidence: 56%

Response of milk fat concentration and yield to nutrient supply in dairy cows

Maxin

Rulquin

Glasser

2011

Animal

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“…In the 3× herds, both fat and protein peaked in the evening; however, fat increased from the morning milking throughout the day to peak at the evening milking, whereas protein tended to increase from a low at the afternoon milking to a peak at the evening milking, then decrease through to the morning milking. The protein percentage had less variability than the fat percentage from milking to milking in both the 2× and 3× herds, in agreement with Gilbert et al (1973) and Syrstad (1977). The fat and protein patterns displayed the most consistency over the 5-d sampling period in comparison with milk yield results in both 2× and 3× herds (Figures 1 and 2).…”

Section: Variability Of Milk and Milk Componentssupporting

confidence: 62%

Milking-to-Milking Variability for Milk Yield, Fat and Protein Percentage, and Somatic Cell Count

Quist

LeBlanc

Hand

et al. 2008

Journal of Dairy Science

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The main objectives were to analyze milking-to-milking variability in milk yield, fat and protein percentages, and somatic cell count (SCC). Additional objectives were to investigate the factors that affect variation in milk fat percentage and to study the seasonal variations in milk, fat, and protein yields and SCC. A total of 16 farms (14 milked 2x and 2 milked 3x) across Canada participated in a 5-d milk-sampling study, with 27,328 milk samples collected and analyzed for fat and protein yields and SCC. Descriptive statistics for both 2x and 3x herds for milk yield and fat and protein percentages followed a typical pattern throughout lactation, and the somatic cell linear scores were higher in early lactation for first-lactation cows (4.7 vs. 3.8) but were higher at the end of lactation for cows in second lactation or greater (5.1 vs. 4.9). The 2x herds had higher milk yields in the morning (approximately 17 vs. approximately 14 kg), whereas the 3x herds had the lowest milk yields in the morning, and yields peaked at the evening milking (approximately 9 vs. approximately 11.2 kg). A herd management questionnaire was distributed to participating producers to investigate the relationship between management variables and variations in milk fat percentage over the 5-d sampling period. Data from the questionnaire determined that milking period had a significant effect on milk fat in 2x herds, with fat percentage 1.11% lower in the morning compared with the evening milking period. Seasonal differences in milk, fat, and protein yields were investigated in 910 cows on 3 farms, with 5,517 fat and 5,534 protein samples. The seasonal differences in fat yield [summer = 1.02 +/- 1.05 kg/d (SEM); winter = 1.19 +/- 1.05 kg/d] and protein yield (summer = 0.85 +/- 1.05 kg/d; winter = 0.96 +/- 1.05 kg/d) were significant only for first lactation. Understanding the variability in milk yield, fat and protein percentages, and SCC is important when making management decisions and in milk-recording programs.

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“…It is well known that milk composition (Syrstad, 1977) has a daily variation. Despite this, sampling milk for evaluation of milk quality on one or two occasions is valuable since this is the common routine in official milk recording.…”

Section: Introductionmentioning

confidence: 99%

Udder quarter milk composition at different levels of somatic cell count in cow composite milk

Forsbäck

Lindmark-Månsson²,

Andrén

et al. 2009

Animal

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Automatic milking systems have made possible the separation of high-and low-quality milk at the udder quarter level during the milking process. The aim of this study was to investigate the composition and yield of milk from individual udder quarters to determine whether deteriorated milk composition occurs in udders that are assumed to be healthy and whether quarters with high-quality milk are found in udders with high milk somatic cell count (SCC). Milk samples were collected on one occasion from 90 cows at udder quarter level and cow composite level. The milk was analyzed for content of total protein, whey protein, casein, fat, lactose, citric acid and SCC; milk yield was registered. The cows were divided into three groups depending on the SCC of their composite milk. Cows in group 1, cow composite SCC , 100 000 cells/ml, were assumed to have healthy udders. However, instances of increased SCC and decreased milk quality were discovered in one or more udder quarters of approximately 30% of the group. Cows in group 2, cow composite SCC of 100 000 to 300 000 cells/ml, and group 3, cow composite SCC . 300 000 cells/ml, were assumed to have affected udders. However, the majority of these cows had one or more udder quarters in which increased SCC and deteriorated milk quality were not detected. Calculations of bulk-tank milk values, when separation of milk from affected udder quarters was performed, indicate that SCC changes to a much greater degree compared to the other milk components. These results show that milk from affected udder quarters suffers compositional changes, but calculations of simulated separation indicate that the compositional changes in bulk-tank milk are small. The effect of separation of milk from individual udder quarters on bulk-tank milk needs to be further studied.

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Day-to-day variation in milk yield, fat content and protein content

Cited by 20 publications

References 1 publication

Response of milk fat concentration and yield to nutrient supply in dairy cows

Response of milk fat concentration and yield to nutrient supply in dairy cows

Milking-to-Milking Variability for Milk Yield, Fat and Protein Percentage, and Somatic Cell Count

Udder quarter milk composition at different levels of somatic cell count in cow composite milk

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