A simple technique to measure udder volume in dairy cows using aluminum foil was developed and used to characterize empty udder volume (EUV) in a dual purpose herd (Bos taurus × B. indicus). The technique was calibrated by comparing cows' actual milk yield with the difference between its EUV and full udder volume (FUV). The resulting relationship was: Actual milk volume = 0.718(±0.9568) + 0.954(±0.0775) * (Calculated milk volume), R 2 = 0.949. In 24 lactating cows, EUV was correlated with calving number and milk yield. Estimated mammary parenchyma productivity was 1.85 ± 0.117 ml/L of EUV. The technique developed is a quick, cheap and yet precise alternative to measure udder volume.

Valencia, J., Arroyo, J., Trujillo, J., Magana-Sevilla, H. and Zarco, L. 2010

Cumulative milk volume (CMV) and milk secretion rate were estimated in eight B. taurus x B. indicus cows. Cows were in peak lactation (~45 days), routinely milked twice a day, supplemented at each milking with about 3 kg DM in concentrate and grazing star grass (Cynodon nlemfluensis) with the main herd as to cover the AFRC (1993) energy and protein requirements. CMV and secretion rate were estimated by milking each cow at 3, 6, 9, 15 and 24 h intervals. Each milking interval measurement was on different days within the same week. Measurements were performed four times for each time interval in four weeks. Empty udder volume (EUV) was measured during the 2 nd week of the experiment. Five IU i.m. oxytocin was used both at previous and scheduled milking interval as well as for the EUV measurement to ensure complete udder emptiness. For 3, 6, 9, 15 and 24 h milking intervals, CMV (L) were 0.38, 0.74, 1.237, 1.69 and 2.40±0.041 per L EUV, while, milk secretion rate (L·h indicus cows is similar to dairy cattle. CMV and milk secretion rate must be taken in consideration when designing milking and restricted suckling regimes for this type of cattle.

The shape of the lactation curve (description of milk production through lactation) which is relevant in order to predict past, current and future lactations. Curves type I show fast increment during early lactation, followed by a slow decline. However, continuous decreasing curves, named type II (Landete-Castillejos and Gallego, 2000) are frequent in tropical diary cattle, maybe due to low nutritional status (Contreras and Rincon, 1979). Curves type II could not be accurately described by Wood (1967) model. In addition, Wood’s model do not describe the inner processes in the udder. Recently, Pollot (2000) presented a mechanistic model, with 3 components and an inherent biological meaning on its parameters. The objective of the present work was to compare the ability of Wood (1967) and Pollot (2000) models to describe dual purpose cattle lactation curves and provide a first description and analysis of the B. taurus x B. indicus typical lactation curve using Pollot’s (2000) model.