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

Abstract

This review discusses the effects of starch and fat before and after calving on metabolism, energy balance (EB), milk production, and reproduction in dairy cows. The shift in dairy cows from a pregnant nonlactating state to a non-pregnant lactating state induces physiological changes, which affect the metabolic and endocrinal axes to redirect body energy stores towards the mammary gland for milk production. Overfeeding high starch and fat levels during the dry period after calving may result in cows failing to adapt to the negative energy balance (NEB) because of major liver and rumen dysfunction. Alternatively, keeping dry cows on high-forage/low-energy diets adjusts dry matter intake (DMI) to optimize the rumen function and decrease the severity of the NEB during transition. These periparturient biological improvements in dairy cows showed real benefits such as fewer postpartum health complications (e.g. milk fever, ketosis, mastitis, metritis), decreased body condition loss and improved reproductive axis in the subsequent lactation. Adding dietary starch and/or fat to diets of dairy cows following parturition increased milk yield. In addition, milk protein of dairy cows increased with glucogenic diets, but decreased with lipogenic diets. Inversely, milk fat usually increases after feeding lipogenic diets, but it decreases when feeding glucogenic diets to dairy cows. Glucogenic and lipogenic nutrients can affect the cow's metabolism and its EB status positively, as is evidenced by plasma non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), glucose, amino acids, insulin, insulin-like growth factor-I (IGF-I), growth hormone (GH), gonadotropin hormones, and progesterone (P 4 ) levels. These metabolites (NEFA, BHB, glucose, amino acids) and hormones (insulin, IGF-I, GH, P 4 ) have been shown to affect folliculogenesis, ovulation, conception, and pregnancy success. Feeding a starchbased diet to dairy cows can lead to acidosis and increase glucose and insulin levels, while decreasing NEFA and BHB levels. Furthermore, an insulinogenic diet favours an early resumption of ovarian activity, but has adverse effects on the quality of oocytes. In contrast, keeping dairy cows on a fat-based diet elevates NEFA and BHB levels and decreases glucose and insulin levels. Additionally, a lipogenic diet increases the plasma P 4 levels and improves the quality of oocytes. These evidences suggest that reproductive performances in dairy cows can be enhanced by feeding an insulinogenic diet until the resumption of the ovarian cycle then switching to a lipogenic diet from mating period onwards. Since long-term field studies on fertility are limited and the reproduction process in dairy cows is multi-factorial, further research is needed on the pre-and postpartum effects of starch and/or fat as well as their combinations on reproduction axis and thus to draw conclusions on reproductive performances.

Role of Fatty Acids in Milk Fat and the Influence of Selected Factors on Their Variability—A Review

“…Therefore, cows, like other lactating animals, often enter a negative energy balance (NEB) at the start of lactation [ 83 ], approximately during the initial 30 days [ 84 ], or even up to 70 to 84 days postpartum (pp) [ 85 ]. Mammary function has metabolic priority and thus, in the NEB state, the limited available nutrients in an organism are directed to milk synthesis for survival of offspring [ 86 ]. Body reserves (fat, and to a lesser degree, protein) are mobilized [ 87 ] through homeostatic regulation [ 85 , 88 ].…”

“…Consequently, non-esterified FAs (NEFAs) are released from body fat reserves, with increasing NEFA levels in blood suggesting a shortfall in energy balance [ 92 ]. NEFA metabolites are directed into the mammary gland to supply milk triglycerides or utilized in the liver [ 86 , 93 , 94 , 95 ].…”

“…Thus, the beginning of lactation is the most demanding period in terms of energy status and also herd health management [ 83 , 86 , 96 , 97 ]. High utilization of energy reserves during this period is reflected in milk fat content [ 98 ], namely in the FA composition and mutual ratios between individual FA groups [ 99 ].…”

Rumen-protected glucose stimulates the secretion of reproductive hormones and the mTOR/AKT signaling pathway in the ovaries of early postpartum

“…These results suggested that a glucogenic diet could stimulate the ovary to utilize glucose, improving somatotropic axis synergies with the gonadotropins (FSH, LH, and P4, etc.) in post-partum dairy cows 28 .…”

Evaluation of Mineral Contents in Milk of Dairy Cattle Fed Elephant Grass Planted at Ex-Coal Mining Land

“…This result agreed with Hess et al (2019) who reported that the grain component of the basal diet did not affect milk yield of dietary fat supplements. Admittance levels and types of dietary energy sources, such as starch and fat, affected plasma metabolite profiles, milk production, and fertility of dairy cattle (Useni et al, 2018). In addition, feeding fats have a positive effect on fertility and a tendency to increase production when fed during the transition period (Rodney et al, 2015).…”