This study aimed to determine the effects of age at first gestation on offspring growth performance, glucose metabolism, and IGF1 concentration. Heifers impregnated by AI from a single bull at 15 months of age (15 M, n = 20), or 27 months of age (27 M, n = 20), and multiparous cows (adult, n = 20) were used. Dams from all groups were managed in a single group during gestation and lactation. Gestational length was longer in the 15 M and 27 M than in adult dams (p = 0.009). Bodyweight at birth, at weaning and ADG during lactation were higher in calves from adult dams than in those from 27 M dams, and higher in calves from the latter than in 15 M calves (p < 0.001). Calves from 15 M dams had an increased head circumference/BW ratio compared to calves from 27 M dams, while calves from this latter group had an increased ratio compared to calves from adults (p = 0.005). Body mass index was greater in calves from adults than in those from 15 M and 27 M dams (p = 0.002). Milk production from 15 M and 27 M dams was similar but lower than that from adults (p = 0.03). Calves born from adult dams had greater blood glucose concentrations than those from 15 M and 27 M dams (p < 0.05). Serum IGF1 concentrations were higher in calves from adults than in calves from 15 M and 27 M dams (p = 0.01). This study showed that age at first gestation affects offspring postnatal growth performance, glucose metabolism and IGF1 concentration.

The objective of this study was to determine how weaning age, days on supplements, and lipid supplementation affected the growth and marbling deposition of steers. Steers from a single sire were early weaned (n = 24) at 150 ± 11 days of age or traditionally weaned (n = 24) at 210 ± 11 days of age. Steers were assigned to control (n = 12/weaning group) or an isocaloric, isonitrogenous rumen by-pass lipid (RBL, n = 12/weaning group) for either 45 (n = 6/treatment) or 90 (n=6/treatment) days then harvested. Steer body weight (BW) was recorded on days −14 and −7, then BW and blood samples were collected on days 0, 22, 45, 66, and 90. The right rib section of each animal was collected for proximate analysis. Longissimus dorsi from RBL steers had increased lipids compared with control steers (3.6 ± 0.2 vs. 2.4 ± 0.2% on a wet basis; p < 0.0001). Steers fed for 90 days had greater (p = 0.02) concentrations of Longissimus dorsi lipid (3.3 ± 0.2%) than those fed for 45 days (2.7 ± 0.2%). There was a weaning age by treatment by days on feed interaction for intramuscular adipocyte diameter (p = 0.02) in which early weaned RBL fed for 90 days steers had an increased adipocyte diameter compared to the early weaned control fed for 90 and early weaned fed for 45 days steers with all other treatment groups as intermediates. Supplementation of RBL increased concentrations of C18:2, C20:4, and total fatty acids on days 45 and 90 (p ≤ 0.05). Data show that RBL supplementation increased the marbling content of the Longissimus dorsi. Furthermore, a longer period of supplementation resulted in increased adipose diameter.

Context: Cow–calf operations in Argentina are managed under extensive grazing condition and the quality of forages is often poor during the second half of gestation. The severity of nutrient restriction in bovine gestation, caused by seasonal pasture production, often results in poor production traits in progeny. Aims: The objective of the current study was to determine whether different levels of maternal nutrient intake in beef cows during late gestation affect fetal and postnatal growth, glucose metabolism, and insulin-like growth factor 1 (IGF1) concentrations in offspring of beef cattle. Methods: At 180 ± 4 days of gestation, multiparous Angus cows (n = 56) were blocked by bodyweight (BW) and expected calving date, and assigned to pens (2 or 3 cows/pen). Pens (n = 8 per treatment) were then randomly assigned to the following treatments: severely restricted (SR; 50% of net energy and 58% of CP requirements), moderately restricted (MR; 75% of net energy and 85% of CP requirements), or control (CON; 100% of net energy and 116% of CP requirements). Pen was the experimental unit and data were analysed by ANOVA or repeated measures analysis, as appropriate. After calving, all cows were managed in a single group until weaning. Key results: Cow BW and body condition score decreased as nutritional restriction increased (P < 0.05). At parturition, birth weight of calves from SR dams and MR dams was lower than that of calves from CON dams (P = 0.05; 4.9 kg and 2.1 kg respectively). Average daily gain of calves from birth to 24 days of age was higher (P = 0.01) in calves from SR dams than in calves from CON and MR dams. Calves from MR dams were lighter (P = 0.04) than were calves from SR and CON dams at weaning. Treatments did not affect milk production or composition (P > 0.10) or glucose–insulin metabolism of offspring during lactation (P > 0.10). Concentration of IGF1 tended to be lower in MR progeny than in SR and CON progeny during lactation (P = 0.09). Conclusions: Late gestation maternal nutrient restriction, irrespective of the severity of the restriction, decreased birth weight of offspring; however, severe nutrient restriction induced early postnatal compensatory growth. Implications: The severe nutritional restriction produced calves with weaning weights indistinguishable from the control cows due to early postnatal compensatory growth. However, the longer-term effects of nutritional restriction of the dam in the second half of pregnancy on metabolic and reproductive performance in replacement heifers or meat production/quality in steers is yet to be determined.

Cow calf operations in Argentina are managed under extensive grazing condition and the quality of forages is often poor during the second half of gestation. The present work investigated the effects of two levels of crude protein (CP) provided to mature dams during late gestation on their subsequent reproductive performance and milk yield, heifer’s (F1) postweaning growth, reproductive performance, milk production and grand offspring growth (F2). Sixty eight multiparous cows were randomly assigned to either low (LP, 6% CP) or high protein (HP, 12% CP) diets. Body weight (BW) and body condition score (BCS) of cows were determined, and milk production was measured until weaning. In the female, progeny time and BW at puberty, were determined. Reproductive and milk performance of female offspring until weaning, were recorded, as well as their offspring growth until weaning. The HP cows had greater BW gain during the prepartum period (P < 0,01) and tended to gain more BCS (P = 0,06) than LP cows. Pregnancy rates, milk production and composition were not influenced by dietary treatments. At puberty (P = 0,01) and pregnancy diagnosis (P = 0,05), HP heifers were heavier than LP heifers. No dam nutrition effects were found on offspring age at puberty (P = 0,98), final pregnancy rate (P = 0,28) or milk yield (P = 0,76), but heifers born from LP dams had greater milk protein percentage (P = 0,04) and tended to produce more milk fat percentage (P = 0,08) compared with HP heifers. The LP grand offspring grew faster from birth until weaning compared with HP grand offspring (P < 0,01). In conclusion, protein level of the diet during the prepartum period in multiparous beef cows affected the BW change at calving, without consequences on reproductive performance and milk quality and yield. Protein supplementation during late gestation did not affect reproductive performance of the offspring heifers but did impact their BW evolution, milk quality and grand offspring performance. The use of diet with low amount of protein during late gestation can affect progeny development and ability to nourish subsequent generations.