Effects of Milk Urea Nitrogen (MUN) and Climatological Factors on Reproduction Efficiency of Holstein Friesian and Jersey Cows in the Subtropics

Abstract

This study investigated the effects of MUN and climatological factors on the inter calving period (ICP), reproductive performance (RP%), and reproductive index (RI) in Holstein Friesian (n = 1177) and Jersey cows (n = 3305) in different seasons in the subtropics. Threshold values for MUN on the reproduction of dairy cows in the subtropics remain controversial due to complex environmental interactions, especially with high environmental temperatures. A retrospective analysis was conducted of data obtained from the National Milk Recording scheme of the Agricultural Research Council (ARC) in South Africa. The results confirm that MUN influences the reproduction of dairy cows in the subtropics. MUN concentrations exceeding 18.1 ± 4.28 mg/dL in Holstein Friesian cows and 13.0 ± 4.70 mg/dL in Jersey cows extended the inter calving period (ICP), and decreased RP% and RI. Jersey cows have a lower threshold MUN concentration compared to Holstein Friesian cows, but they are not adversely affected by high humidity or temperatures, while Holstein Friesian cows are.

Association between metabolic parameters and embryo production in superovulated dairy cattle

“…NEFA and BHB parameters are known as the indicators of negative energy balance in cattle (Kang et al, 2020;Van der Drift et al, 2012). Furthermore, NEFA and BHB levels are highly affected by feeding regimens and metabolic factors (Xu et al, 2010). Many authors consider BHB concentrations between 1.2 and 2.9 mmol/L as subclinical ketosis and ≥3.0 mmol/L as clinical ketosis Benedet et al (2019).…”

“…BUN value is a parameter used to indicate the protein/energy ratio in the diets of healthy dairy cows (Webb & De Bruyn, 2021).…”

Rumen‐protected l‐carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes

“…As a consequence of increasing the dietary CP, the BUN levels would be elevated along with the urea and ammonium levels in ovarian follicles and uterus (Butler, 2005). Study on Holstein dairy cows pinpointed clear negative impact of higher milk urea‐N (MUN) levels on reproductive performance of animals (Webb & de Bruyn, 2021). As urea is able to diffuse from the blood into the milk, the concentration of BUN directly affects MUN concentrations in lactating ruminants.…”

Relationships among total mixed ration nutritional components and reproductive performance in high-producing dairy herds

“…The lack of an association of dietary protein with any of our reproductive measures is interesting; however, it should be noted that the variation in dietary CP, RDP, and RUP levels was not as large as variation in other components of the diets. Some previous studies have noted a negative association of BUN or MUN on reproduction ( Webb and de Bruyn, 2021 ). The observed MUN can be influenced by CP, RDP, and RUP levels, as well as the quality of protein, and energy in the diet.…”