Milk productivity is believed to have risen with increased genetic progress and improved farm management last decade. However, quantification of this fact remains unclear. With the desire to better represent current animal performance in the RuFaS model, we investigated to what degree milk productivity has improved during 10 yr and how this translates into lactation curve parameters. We fitted Holstein and Jersey test-day milk production data from 2006, 2011, and 2016 to the Wood’s lactation curve function (y = at^be^-ct) using the least square method. As input, we used the data set provided by the Council on Dairy Cattle Breeding consisted of 12.82 million individual lactations each had at least 10 test-day records. We chose to fit separate curves for breed, state, and parity with pre-processed data. We averaged milk yield for every 10 DIM and set the cut-off point at 365 DIM to reduce variation, improve goodness of fit, and eliminate the effect of later records. For the state of Wisconsin, our results show increased 305-d milk yields and postponed, higher peaks in 2016 compared with 2011 and 2006 for each breed and parity. In general, Holstein curves had greater scale of production (a in the wood’s model), faster rate of increase to peak (b), and higher rate of decline after peak (c) than Jersey curves. Wisconsin updated Wood’s lactation curve parameters from year 2016 are reported in the table below. The RuFaS model will incorporate the parameters from this data set according to breed, parity, state, and milk component curves. These will allow possible reflection of daily production divergence caused by diet alterations, pregnancy, or health issues and will be used to predict milk yields and better inform management decisions. Table 1 (Abstr. M128).

Parity	Breed	No. of lactations	Wood’s fitted parameters
a (kg/d)	b	c
1	Holstein	109,534	16.13 ± 0.28	0.235 ± 0.0046	0.0019 ± 3.77 × 10−5
Jersey	2,901	14.07 ± 0.39	0.186 ± 0.0076	0.0021 ± 6.60 × 10−5
2	Holstein	80,776	23.61 ± 0.54	0.227 ± 0.0064	0.0032 ± 5.82 × 10−5
Jersey	2,179	19.26 ± 0.49	0.173 ± 0.0071	0.0028 ± 6.69 × 10−5
>2	Holstein	88,613	23.81 ± 0.51	0.244 ± 0.0060	0.0036 ± 5.54 × 10−5
Jersey	2,826	19.21 ± 0.47	0.190 ± 0.0069	0.0032 ± 6.53 × 10−5