BEEF cow gestational nutrition may hold the key to a serious congenital defect of beef calves, according to Michigan State University associate professor and beef extension specialist Dan Buskirk.

Affected calves, called "acorn" calves or "bulldog" calves, are the result of conditions referred to as congenital joint laxity and dwarfism, congenital spinal stenosis or congenital chondrodystrophy of unknown origin (CCUO). An association between CCUO and grazing drought-affected pastures, feeding silage-only diets or supplementing with apple pulp strongly suggests a nutritional link.

According to Buskirk, skeletal system deformity in calves was first reported in 1932 in California's Sierra Nevada region. Ranchers referred to the deformed animals as acorn calves due to a belief that the condition resulted from dams ingesting acorns during the gestation period. However, this theory was dismissed after the deformity also was observed in calves from dams with no access to acorns.

Today, the condition, now called CCUO, is frequently reported in the northern U.S. and Canada. It may afflict only a few calves or many in a herd, Buskirk explained.

Calves affected with CCUO are characterized at birth by bowed legs or sickle-shaped legs with weak joints (joint laxity), shortened legs (disproportionate dwarfism) and, in some cases, a notable underbite (superior brachygnathia). Joint laxity may contribute to increased calving difficulty and elevated early calf mortality rates, as well as to a staggering or wobbly gait, Buskirk noted.

"Within a few weeks following birth, joints of surviving calves may begin to stabilize, allowing calves to walk more normally," he said. "However, affected calves typically remain much smaller in stature and slower growing than their normal herd mates."

Cause. Although the definitive cause of CCUO has not been determined, the condition in the U.S. and Canada has often been associated with feeding solely fermented forages to spring-calving cows during mid- to late-gestation, Buskirk explained, adding that these diets usually lack dry feed or grain supplementation.

"Presence of a factor, or factors, unique to specific geographical areas may cause CCUO, but most investigators are convinced that the underlying cause relates to a maternal nutritional deficiency," he noted.

Some evidence correlates the condition to low concentrations of liver manganese, Buskirk said.

"It is possible that bioavailability of manganese is reduced in ensiled forages, although other minerals or factors may contribute to the necessary conditions to trigger CCUO. The apparent good health and generally good mineral status of dams giving birth to CCUO calves suggests that any nutritional deficiency arising during gestation may be either short term — resolving before symptoms are shown in dams — or not severe enough to affect dam health," he noted.

Prevention. In all recorded outbreaks of CCUO, spring-born calves appear to be most susceptible, according to Buskirk. This corresponds with mid-gestation supplemental feeding or grazing of drought-stricken pastures during the last two trimesters of gestation. Additionally, Buskirk suggested that clover or grass silages may cause the greatest risk.

Supplementing silage diets with dry forages or dried grains has been found to reduce or eliminate the risk of CCUO. In one study, feeding an animal as few as 5 lb. of dry hay and 1.5 lb. of dry-rolled barley daily eliminated the condition in cows fed silage diets.

"Though not precisely defined, the critical feeding period is likely within the last 180 days of gestation," Buskirk explained. "Feeding a balanced, loose mineral/vitamin supplement is recommended; however, there is not sufficient evidence to suggest that mineral supplementation alone can prevent the occurrence of CCUO when cows are fed only fermented forages."

Sustainability initiatives

The Global Roundtable for Sustainable Beef (GRSB) held its annual general assembly meeting in October and provided updates on GRSB initiatives, including: enhanced communications, antibiotic stewardship, global indicators and equivalence.

Around 75 individuals representing 28 member organizations attended the meeting in Amsterdam, Netherlands.

"We had more than a 50% increase in attendance this year," GRSB executive director Ruaraidh Petre said. "The meeting provided a sense of the progress and increased enthusiasm to grow the momentum of the organization. Most importantly, it provided a sense of the value and indicators of progress in making the beef industry more sustainable worldwide."

The meeting focused on GRSB's "Principles & Criteria for Global Sustainable Beef," a document developed in 2014 that defines the attributes of sustainability to which GRSB is committed while also recognizing that production systems and value chains vary in sustainability across regions and countries.

Regional roundtables, including the Brazilian Roundtable on Sustainable Livestock, Canadian Roundtable for Sustainable Beef, U.S. Roundtable for Sustainable Beef and roundtable groups in Europe, Colombia and Mexico, provided updates and progress on sustainability initiatives in their respective areas.

Over the past several months, the global-to-local model of the regional roundtable process also resulted in two technical working groups focused on accreditation and global indicators that reported multiple meetings and progress throughout the year.

Additional areas of focus included initiatives in 2016-20 to move the organization forward in supporting sustainability within the beef value chain, such as an enhanced communications effort.

GRSB hosted a number of guest speakers on various topics important to the beef value chain. Dr. Hetty van Beers-Schreurs, managing director of the Netherlands Veterinary Medicine Authority, provided a presentation on antibiotic resistance and policy. Dr. Martin Scholten, managing director of the Animal Sciences Group at Wageningen University in the Netherlands, spoke on food production and food security. Brian Lindsey, development director of Global Dairy Agenda for Action, updated the GRSB board of directors on dairy sustainability.

"There was a strong appreciation for the quality of guest speakers as well as the regional updates," Petre said. "This next year, GRSB will hit the ground running in the sense of more attention to the development of global indicators of sustainability."

Petre said ideas on beef sustainability still greatly differ.

"The GRSB principles and criteria for defining global sustainable beef have achieved a very strong and valuable framework in which regional roundtables may develop key indicators and measureable results, and measureable results will be a critical focus for the organization moving forward," Petre said.

Volume:87 Issue:48