Impact of dietary supplementation of beef cows with rumen-protected methionine during the periconceptional period on post-weaning performance of female offspring

Changes in maternal nutrition in the periconceptional period can have long term effects on the offspring. The aim of the current study was to determine the influence of feeding 15 g of rumen-protected methionine (RP-Met) during the periconceptional period on female progeny during the post-weaning phase until puberty. A total of 114 beef cows were fed a roughage-based diet and randomized to receive corn gluten feed supplemented with 15 g of RP-Met (Smartamine M, Adisseo) or not (CON) from day -7 to +7 relative to artificial insemination with female sex-sorted semen. Female calves (n = 32) remained with their dams until weaning. A month after weaning, calves were weighed every 14 d, and withers height (WH), body length (BL), and heart girth (HG) were measured during the post-weaning phase. At 420 ± 13 d of age, a 56-d performance test was conducted, and initial body weight (IBW), final body weight (FBW), dry matter intake (DMI), average daily gain (ADG), and residual feed intake (RFI) were measured. At the end of the performance test, the 12th rib back fat thickness (BF), ribeye area (REA), intramuscular fat (IMF), and rump fat thickness (RF) were determined via ultrasound. Data from the post-weaning phase, performance test, and body composition were analyzed as a RCBD using generalized linear mixed models through the MIXED procedure of SAS, with body measurements analyzed as repeated measures. A treatment-by-day interaction (P = 0.003) was observed for HG, with larger HG for RPM from day 308 onwards. Final BW was greater for RPM heifers (CON = 436.13 ± 1.43 kg; RPM = 445.63 ± 1.52 kg; P < 0.01). Also, RPM heifers had a greater ADG than CON heifers (CON = 1.40 ± 0.04 kg; RPM = 1.65 ± 0.04 kg; P < 0.01). No treatment difference (P > 0.05) was observed for DMI (CON = 12.06 ± 0.19 kg/d; RPM = 12.14 ± 0.18 kg/d) or RFI (CON = -0.12 ± 0.15; RPM = 0.11 ± 0.14). There was also no effect of treatment (P > 0.05) on REA or IMF. RF was less for RPM (CON = 1.16 ± 0.07 cm; RPM = 0.91 ± 0.06 cm), and there was a tendency (P = 0.07) for lesser BF in RPM. In conclusion, supplementing dams with RP-Met enhanced FBW of their heifer progeny during the performance test; furthermore, a treatment-by-day interaction tendency was observed for HG. RPM heifers also had reduced RF and a tendency for reduced BF.