Milk, protein, fat and lactose yields of lactating dairy cows treated with growth hormone.

<p>Growth hormone (GH) treatment significantly increased milk (A), protein (B), fat (C) and lactose (D) yields from d 4 to d 6, compared to controls (<i>n</i> = 4 per treatment). To assess differences between treatment groups a linear model, including fixed effects of treatment and day effects and their interaction was used. Measurements collected daily over the experiment were treated as repeated measurements using cows within treatment as the subjects, as per Littell et al [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134323#pone.0134323.ref022" target="_blank">22</a>]. The figures show least squares means; Asterisks denote significant differences between treatments (*: <i>P</i> < 0.05); (**: <i>P</i> < 0.01). Error bars denote the standard error of the mean. Milk and protein yield data adapted from Hayashi et al (2009).