Effect of grass dry matter intake and fat supplementation on progesterone metabolism in lactating dairy cows

Abstract

39Progesterone (P4) metabolism in dairy cattle can be manipulated by alterations in dry 40 matter intake and diet composition. Our objectives were to determine the effects of 41 grazing allowance and fat supplementation on P4 metabolism in lactating dairy cows. 42Forty mid-to late-lactation Holstein-Friesian dairy cows were used in a completely 43 randomised block design, with a 2 x 2 factorial arrangement of treatments. Cows were 44 assigned to receive 1 of 2 pasture allowances [ad libitum allowance (AL -9.5 kg 45 DM/day) or restricted allowance (R -7 kg DM/day)] and 1 of 2 fat supplementation 46 treatments [750 g/day saturated fat (F) or no fat supplement (NF)]. All cows received 47 an additional 4 kg/d of concentrate. Grass dry matter intake (GDMI) was measured 5 48 wk after the initiation of dietary treatment. Cows were treated with prostaglandin F 2α 49 Revised 3 (PGF 2α ) to eliminate the endogenous source of P4, and 2 intravaginal progesterone 50 releasing devices (CIDR) were inserted into each cow for a period of 8 days. Regular 51 blood samples were taken prior to and following the removal of the CIDRs, and 52 analysed for P4 concentrations. The half-life (t½) and metabolic clearance rate (MCR) 53 of P4 was calculated for each cow. There was no effect of GDMI or fat 54 supplementation on the t½ or MCR of P4. There was a tendency for an interaction 55 between GDMI and fat supplementation on the t½ of P4; cows on the R-F diet tended 56 to have a longer P4 t½ than cows on the AL-F diet. It was concluded that greater 57 alterations in GDMI than achieved in the current study are required to change P4 58 metabolism. A combination of fat supplementation and restricted feeding slows P4 59 clearance, which may have beneficial implications for fertility. 60 KEYWORDS: Progesterone metabolism, dairy cattle, fat supplementation, dry 61 matter intake 62 63

Opportunities and challenges associated with fecal progesterone metabolite analysis

“…Rabiee [ 7 ] and Hutchinson et al . [ 87 ] both opined that feed and dry matter intake affect the total concentration of progesterone metabolites in feces of cows. Furthermore, feed restricted cows have been shown to have a higher concentration of progesterone metabolites in feces [ 7 ].…”

Respuesta reproductiva, metabólica y cambios corporales en ovejas alimentadas con dos niveles de energía

“…El aporte extra de energía en la dieta de ovejas a través de la inclusión de 4% de aceite de palma en ovejas incrementa el metabolismo lipídico, incluyendo colesterol, lo que a su vez incrementa la concentración de progesterona; sin embargo, al incrementar a 6% la inclusión de aceite de palma no se modifica más el metabolismo lipídico y la concentración de progesterona (29), de igual manera en vacas con baja condición corporal en pastoreo y suplementadas con un concentrado con 4% de aceite de maíz se ha reportado que se incrementa la concentración de progesterona y colesterol. Por el contrario, en vacas lecheras se ha encontrado que la diferencia del 12% en el consumo de materia seca de forraje no altera el metabolismo de progesterona (30). En el presente estudio se agregó 3% de aceite de soya en la dieta con 2.5 Mcal kg -1 de EM y se midió la concentración de progesterona en el día 13 post-inseminación ya que es cuando se da la caída natural de progesterona del ciclo estral.…”

Optimizing productive and reproductive performance in the grazing cow

“…The focus of research on supplemental nutrition for pasture based systems in recent years has focussed on specific polyunsaturated fatty acid (PUFA) supplements (McNamara et al 2003, Hutchinson et al 2012a, Hutchinson et al 2012b, Hutchinson et al 2012c. Responses in terms of improved fertility performance have been small or non-existent.…”