%0 Journal Article
%T Milk Yield and Composition and Pasture Ruminal Digestion in Grazing Dairy Cows Receiving Three Levels of Energy Concentrate Supplementation
%A Eloy Eduardo Salado
%A Gustavo Bretschneider
%A Alejandra Cuatrin
%A Adriana Mar¨ªa Descalzo
%A Gerardo Antonio Gagliostro
%J Agricultural Sciences
%P 1135-1156
%@ 2156-8561
%D 2017
%I Scientific Research Publishing
%R 10.4236/as.2017.810083
%X <div style=\"text-align:justify;\">
	The objective of the experiment was to determine the effect of feeding three
levels (T3.5, T7.0 and T10.5) of energy concentrate (3.5, 7.0 and 10.5 kg cow<sup>-1</sup> day<sup>-1</sup>) on total dry matter (DM) and energy intakes, milk yield and composition,
nutritional value of milk and rumen pasture neutral detergent fiber
(NDF) digestion in grazing dairy cows. Twenty-one multiparous Holstein
cows in early lactation (70.2 ¡À 13 days postpartum) producing 37.1 (¡À4.7) kg
of milk were assigned to a 3 treatments (7 cows/treatment) ¡Á 3 periods Latin
square design. Parameters of ruminal environment and pasture NDF degradation
were obtained using 3 additional cows of the same breed fitted with rumen
cannulae. On a wet basis, concentrate was composed by corn grain
(68%), soybean meal (22%), wheat bran (8%) and a vitamin-mineral nucleus
with monensin. Pasture (<i>Medicago sativa</i>, sp) was used in a rotational grazing
system with an herbage allowance of 30 kg DM cow<sup>-1</sup> d<sup>-1</sup>. Yield (kg cow<sup>-1</sup> d<sup>-1</sup>)
of fat corrected milk (4% FCM) resulted higher (<i>p</i> &lt; 0.05) in T7.0 (29.0) compared
to T3.5 (26.8) but similar to T10.5 (30.2). Milk and protein yields were
linearly increased (<i>p</i> &lt; 0.01) by concentrate intake. Milk fat (3.13 g/100g) and
total solid contents (11.79 g/100g) did not differ whereas milk protein (<i>p</i> &lt;
0.03) and casein (<i>p</i> &lt; 0.01) levels (g/100g) increased linearly from 3.05 to 3.10
(protein) and from 2.42 to 2.47 (casein). Pasture intake decreased but total DM
and energy consumption were enhanced showing addition effects after concentrate
feeding. Body weight (BW) loss and plasmatic levels of non esterified fatty acids (NEFA) decreased with concentrate intake. Circulating levels of
insulin-like growth factor-I (IGF-I) were higher (<i>p</i> &lt; 0.05) in T10.5 while
those of glucose, plasma urea nitrogen, insulin and somatotrophin were not
affected. Ruminal pH and acetate concentration resulted lower (<i>p</i> &lt; 0.05) in
T10.5 when compared to T3.5. The acetate:propionate ratio decreased (<i>p</i> &lt;
0.01) from 4.25 in T3.5 to 3.08 in T10.5 and ruminal ammonia nitrogen levels
tended (<i>p</i> &lt; 0.07) to be lower as concentrate intake increased. Kinetics parameters
of NDF degradation remained unchanged. The potential hypercholesterolemic
fatty acids (FA) of milk (C12:0 to C16:0.) remained unchanged as
concentrate intake increased. Milk content of linolenic acid decreased and the
n-6:n-3 ratio increased with concentrate intake from 1.56
%K Grazing Dairy Cows
%K Milk Yield
%K Concentrate Supplementation
%K Rumen Digestion
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=79837