Starch source and content in postpartum dairy cow diets: Effects on plasma metabolites and reproductive processes

Abstract

The objective of this study was to examine the effects of dietary starch source and content in the immediate postpartum period on plasma metabolites and hormones and ovarian follicular development. One of 3 diets was fed in a randomized block design to 40 cows from calving until 70 d in milk. The diets contained 45% alfalfa silage (AS), 45% barley silage (BS), or 41% barley silage and 4% supplemental starch (SS) on a dry matter basis. All diets contained 45% barley-based concentrate and 10% alfalfa hay. Resulting starch levels were 25.2, 23.3, and 26.7% for AS, BS, and SS, respectively. Body condition was scored every other week and dry matter intake and milk yield were recorded daily. Milk samples were obtained weekly and blood samples were taken at calving and then every other week to determine concentrations of glucose, insulin, insulin-like growth factor-1, β-hydroxybutyrate, and nonesterified fatty acids. Transrectal ultrasonography was performed twice per week from 7 d after calving until first ovulation or 62 d in milk in all cows. For a subset of 7 AS-, 8 BS-, and 9 SS-fed cows, a complete estrous cycle was monitored for ovarian dynamics, and blood samples were collected every second day for progesterone and estradiol. Luteinizing hormone pulsatility was also determined (5 cows/treatment) approximately 15 d postcalving. Treatment had no effect on body condition score, dry matter intake, blood metabolites, milk yield, or milk fat and protein contents, but BS-fed cows had significantly higher levels of milk urea nitrogen compared with SS cows. Cows fed SS (31 d) tended to have a shorter interval from calving to first ovulation than cows fed AS (43 d) or BS (38 d). The incidence of double first ovulations was higher in cows fed SS (46%) compared with those fed BS (0%). Treatment had no effect on LH pulse frequency or amplitude, ovarian dynamics, or progesterone and estradiol concentrations during the observed estrous cycle. Energy balance did not differ among cows fed the 3 diets. Overall, dietary starch source and concentration had little effect on productivity or metabolic status of postpartum cows.

Prepartum and postpartum nutritional management to optimize fertility in high-yielding dairy cows in confined TMR systems

“…In subsequent research, the number of cows pregnant at 120 days was greater for cows fed a glucogenic (high-starch) diet that increased insulin early postpartum followed by the lipogenic diet (higher fat) during the breeding period (Garnsworthy et al, 2009). More recent studies have not confirmed this effect (Dyck et al, 2011;Gilmore et al, 2011) although diets and experimental conditions differed and cow numbers were limited. The aim to increase early postpartum insulin by feeding higher starch diets must be tempered by the need to maintain optimal rumen health and digestion.…”

Pre- and postpartum effects of starch and fat in dairy cows: A review

“…In contrast, other investigations found no or negative effects of the energy intake level on the conception rate following the first insemination (McNamara et al, 2003;Garnsworthy et al, 2009;Gilmore et al, 2011). Furthermore, some studies found improved pregnancy rates when feeding dietary starch or fat to dairy cows (Burke et al, 2010;Reis et al, 2012), while others reported no or negative effects (McNamara et al, 2003;Dyck et al, 2011;Gilmore et al, 2011). However, important enhancements in conception rates were observed when feeding a diet that increased glucose and insulin levels in the early postpartum period and then switching to a diet that reduced insulin levels during the mating period, compared with other treatments (Garnsworthy et al, 2009).…”

“…Manipulating the energy level and source in the diet of pre-and postpartum cows showed significant improvements in terms of decreased incidence of health problems (Beever, 2006), optimized rumen microbial activity (Jouany, 2006), increased amount of digested nutrients from the gastro-intestinal tract (GIT) (Bauman & Currie, 1980), decreased body condition loss (Drehmann, 2000;Butler, 2003), and increased milk responses (Grum et al, 1996;Ingvartsen & Andersen, 2000;Cavestany et al, 2009a;Reis et al, 2012;Damgaard et al, 2013;Roche et al, 2013;Hills et al, 2015). However, studies on the pre-and postpartum effects of starch-or fat-based diets on dairy cow reproduction parameters are contradictory, with some studies reporting a negative effect or lack of effect of it (Beam & Butler, 1997;Oldick et al, 1997;Oldick et al, 1998;McNamara et al, 2003;Van Knegsel et al, 2007c;Dyck et al, 2011;Gilmore et al, 2011), compared with other studies that reported a positive effect (Gong et al, 2002;Cavestany et al, 2009b;Garnsworthy et al, 2009;Reis et al, 2012;Little et al, 2016;Thatcher, 2017). The objectives of this review are therefore to discuss the effects of energy-based diets containing starch and/or fat during the dry and postpartum periods on the subsequent metabolism, milk production and fertility of dairy cows.…”

The effects of varying levels of dietary starch on reproductivetraits in lactating dairy cows

“…Rizos et al (18) showed that the maximum follicle sizes in the first follicular waves after parturition were, on average, 16.8 mm and 18.3 mm in high-energy and control groups, respectively, and differences were found to be insignificant. In one study, Dyck et al (19) found that the maximum follicle size in the first follicular wave was approximately 17.5 mm, and different dietary starch levels (these were 23.3%, 25.2%, and 26.7% in the groups in the study) did not affect ovarian dynamics. We found a smaller maximum follicle size in the first follicular wave than these studies, with no differences among the groups.…”

“…Although many factors affect the resumption of postpartum cyclicity, the maximum follicular size in the first follicular wave is important to the onset of cyclicity in dairy cows. The size and ability of the first dominant follicle to ovulate postpartum are the decisive factors (7,19). It is known that the ovulatory follicle size must be greater than 10 mm (7,16).…”