Phosphorus status of lactating dairy cows fed total mixed rations containing 0.24% vs. 0.36% phosphorus

Abstract

. W. 2005. Phosphorus status of lactating dairy cows fed total mixed rations containing 0.24% vs. 0.36% phosphorus. Can. J. Anim. Sci. 85: 409-412. The effect of dietary P content on P balance was evaluated using 14 lactating dairy cows fed a corn silage based total mixed ration (TMR) containing either 0.24% P or 0.36% P. The animals were paired by calving date at dry-off with one cow from each pair randomly assigned to either dietary treatment. All cows were fed a common TMR containing 0.34% P prepartum, and then 0.41% P for 2 wk postpartum. Experimental diets were fed from 3 to 13 wk postpartum. Phosphorus balance was conducted at week 13 postpartum. Cows fed 0.36% P diet consumed more (P < 0.05) P than the 0.24% P diet cows (69.2 vs. 50.9 g d -1 ) and excreted more (P < 0.05) P in the faeces (49.1 vs. 25.7 g d -1 ). Phosphorus digestibility was lower (P < 0.05) for the 0.36% P diet than the 0.24% P diet (29.0 vs. 48.8%). Dry matter intake and milk yield were not (P > 0.05) affected by treatments. These results suggest that short-term P balance in lactating dairy cows can be maintained on a diet supplying 26% below National Research Council 2001 recommendations of P while reducing the amount of P excreted into the environment. Can. J. Anim. Sci. 85: 409-412. Les auteurs ont évalué l'incidence de la concentration de P dans les aliments sur 14 vaches laitières en lactation nourries d'une ration mixte complète (RMC) à base d'ensilage de maïs renfermant 0,24 % ou 0,36 % de P. Les animaux ont été appariés selon la date de vêlage au tarissement et une vache de chaque couple a été affectée au hasard à l'un des deux traitements. Les vaches ont toutes reçu la RMC enrichie de 0,34 % de P avant la mise bas, puis de 0,41 % de P au cours des deux semaines suivant le vêlage. Les rations expérimentales ont été servies de la 3 e à la 13 e semaine après la mise bas. Le bilan de phosphore a été établi la 13 e semaine suivant le vêlage. Les vaches qui recevaient 0,36 % de P ont absorbé plus de P (P < 0,05) que celles en recevant 0,24 % (69,2 c. 50,9 g par jour) et en ont excrété davantage (P < 0,05) dans leurs fèces (49,1 c. 25,7 g par jour). La digestibilité du P était plus faible (P < 0,05) avec la ration en contenant 0,36 % qu'avec celle en renfermant 0,24 % (29,0 c. 48,8 %). L'ingestion de matière sèche et le rendement laitier ne sont pas affectés (P > 0,05) par le traitement. Les résultats laissent croire qu'à court terme, on peut maintenir le bilan du P chez les vaches laitières en lactation avec une ration renfermant 26 % moins de P que la concentration recommandée par le Conseil national de recherches en 2001 et réduire par la même occasion la quantité de P excrétée dans l'environnement. Mots clés:Bilan du phosphore, vaches laitières, lactation, besoins en phosphore Reducing excessive intake of dietary P in dairy cattle can significantly reduce P excretion in the faeces, which can subsequently reduce the impact that application of dairy cow excreta has on soil P content and the potential for P leaching into waterways (Va...

Long-term effects of feeding diets without mineral phosphorus supplementation on the performance and phosphorus excretion in high-yielding dairy cows

“…This was surprising because decreases in BW have only been reported in dairy cows fed very low dietary P, 0.24% P compared with cows fed diets ranging in P from 0.28 to 0.42% (Valk and Sebek 1999). Cows supplemented with P at 0.42% had higher (P < 0.05) faecal P than cows on the 0.35% P diet, in agreement with previous studies, which have shown that faecal P increases as dietary P increases (e.g., Morse et al 1992;Shore et al 2005). McCaskill (1990) suggested that endogenous faecal P was one of the most important pathways responsible for almost 80% of P leaving the animal.…”

“…The apparent digestibility of P and P balance have been calculated for dairy cows (Martz et al 1990;Spiekers et al 1993;Valk et al 2002), although methods of measurements differ among experiments. When potentially absorbable P is provided in sufficient amounts or in excess, dairy cows appear to have the ability to absorb the amount of P needed Shore et al 2005;Ekelund et al 2006). Efficiency of absorption of P declines as intake of P increases in cattle (Challa et al 1989) and in sheep (Field et al 1977).…”

“…Faecal P increases as dietary P increases Shore et al 2005) and can account for significant P loading of surface water bodies depending on the watershed (Smith and Alexander 2000). Powell et al (2001) estimated that crop acreage required to recycle faecal P was decreased by 39% when dietary P was reduced from 0.48 to 0.38% P on a DM basis.…”

Meta-analysis of factors that affect the utilization efficiency of phosphorus in lactating dairy cows

“…This database subset comprised data from lactating dairy cows from 25 studies (Martz et al, 1990;Morse et al, 1992;Spiekers et al, 1993;Delaquis and Block, 1995;Khorasani et al, 1997;Knowlton et al, 2001Wu et al, 2001Wu et al, , 2003Knowlton and Herbein, 2002;Guyton et al, 2003;Kebreab et al, 2005;Kincaid et al, 2005;Shore et al, 2005;Wu, 2005;Ekelund et al, 2006;Kamiya et al, 2006a;Knowlton et al, 2007;Dann et al, 2008;Moreira et al, 2009;Myers and Beede, 2009;Taylor et al, 2009;Van Straalen et al, 2009;Herrera et al, 2010;Puggaard et al, 2011) and included 130 treatment means. The response variable of interest was P excretion in the feces, both in grams per day and as a fraction of P intake.…”

“…This database subset contained 94 treatment means from 19 studies (Martz et al, 1990;Spiekers et al, 1993;Delaquis and Block, 1995;Knowlton et al, 2001Knowlton and Herbein, 2002;Valk et al, 2002;Guyton et al, 2003;Borucki Castro et al, 2004;Kincaid et al, 2005;Peterson et al, 2005;Roche et al, 2005;Shore et al, 2005;Kamiya et al, 2006b;Odongo et al, 2007;Dann et al, 2008; Table 2.…”